From 913cb043ab58c8e36bb07c0b37bcd7b93f753ac8 Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Wed, 21 Jun 2023 16:36:41 +0900
Subject: [PATCH 01/28] set pool size in client

---
 integration/query_test.go         | 13 ++++++-------
 integration/setup/client.go       | 10 +++++++---
 integration/setup/listener.go     |  2 +-
 integration/setup/setup.go        |  4 +++-
 integration/setup/setup_compat.go |  4 ++--
 integration/setup/startup.go      |  4 ++--
 6 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/integration/query_test.go b/integration/query_test.go
index af115d1968a0..938dc60ef808 100644
--- a/integration/query_test.go
+++ b/integration/query_test.go
@@ -950,7 +950,11 @@ func TestQueryBatchSize(t *testing.T) {
 
 func TestQueryCommandGetMore(t *testing.T) {
 	t.Parallel()
-	ctx, collection := setup.Setup(t)
+	s := setup.SetupWithOpts(t, &setup.SetupOpts{
+		PoolSize: 1,
+	})
+
+	ctx, collection := s.Ctx, s.Collection
 
 	// the number of documents is set to slightly above the default batchSize of 101
 	docs := generateDocuments(0, 110)
@@ -1179,12 +1183,7 @@ func TestQueryCommandGetMore(t *testing.T) {
 				t.Skip(tc.skip)
 			}
 
-			// TODO: https://github.com/FerretDB/FerretDB/issues/1807
-			// Do not run tests in parallel, MongoDB throws error that session and cursor do not match.
-			// > Location50738
-			// > Cannot run getMore on cursor 2053655655200551971,
-			// > which was created in session 2926eea5-9775-41a3-a563-096969f1c7d5 - 47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU= -  - ,
-			// > in session 774d9ac6-b24a-4fd8-9874-f92ab1c9c8f5 - 47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU= -  -
+			t.Parallel()
 
 			require.NotNil(t, tc.firstBatch, "firstBatch must not be nil")
 
diff --git a/integration/setup/client.go b/integration/setup/client.go
index a2d6a78a7132..41027c1128e6 100644
--- a/integration/setup/client.go
+++ b/integration/setup/client.go
@@ -78,9 +78,13 @@ func mongoDBURI(tb testing.TB, opts *mongoDBURIOpts) string {
 }
 
 // makeClient returns new client for the given working MongoDB URI.
-func makeClient(ctx context.Context, uri string) (*mongo.Client, error) {
+func makeClient(ctx context.Context, uri string, poolSize uint64) (*mongo.Client, error) {
 	clientOpts := options.Client().ApplyURI(uri)
 
+	if poolSize != 0 {
+		clientOpts.SetMaxPoolSize(poolSize)
+	}
+
 	clientOpts.SetMonitor(otelmongo.NewMonitor())
 
 	client, err := mongo.Connect(ctx, clientOpts)
@@ -103,7 +107,7 @@ func makeClient(ctx context.Context, uri string) (*mongo.Client, error) {
 //
 // If the connection can't be established, it panics,
 // as it doesn't make sense to proceed with other tests if we couldn't connect in one of them.
-func setupClient(tb testing.TB, ctx context.Context, uri string) *mongo.Client {
+func setupClient(tb testing.TB, ctx context.Context, uri string, poolSize uint64) *mongo.Client {
 	tb.Helper()
 
 	ctx, span := otel.Tracer("").Start(ctx, "setupClient")
@@ -111,7 +115,7 @@ func setupClient(tb testing.TB, ctx context.Context, uri string) *mongo.Client {
 
 	defer trace.StartRegion(ctx, "setupClient").End()
 
-	client, err := makeClient(ctx, uri)
+	client, err := makeClient(ctx, uri, poolSize)
 	if err != nil {
 		tb.Error(err)
 		panic("setupClient: " + err.Error())
diff --git a/integration/setup/listener.go b/integration/setup/listener.go
index 169fbcfcc650..ea3600317b68 100644
--- a/integration/setup/listener.go
+++ b/integration/setup/listener.go
@@ -213,7 +213,7 @@ func setupListener(tb testing.TB, ctx context.Context, logger *zap.Logger) (*mon
 	// those will fail the test if in-process FerretDB is not working;
 	// for example, when backend is down
 	uri := mongoDBURI(tb, &clientOpts)
-	client := setupClient(tb, ctx, uri)
+	client := setupClient(tb, ctx, uri, 0)
 
 	logger.Info("Listener started", zap.String("handler", handler), zap.String("uri", uri))
 
diff --git a/integration/setup/setup.go b/integration/setup/setup.go
index 4bc3d30dad32..c850f6fdfc50 100644
--- a/integration/setup/setup.go
+++ b/integration/setup/setup.go
@@ -86,6 +86,8 @@ type SetupOpts struct {
 
 	// Benchmark data provider. If empty, collection is not created.
 	BenchmarkProvider shareddata.BenchmarkProvider
+
+	PoolSize uint64
 }
 
 // SetupResult represents setup results.
@@ -138,7 +140,7 @@ func SetupWithOpts(tb testing.TB, opts *SetupOpts) *SetupResult {
 	if *targetURLF == "" {
 		client, uri = setupListener(tb, ctx, logger)
 	} else {
-		client = setupClient(tb, ctx, *targetURLF)
+		client = setupClient(tb, ctx, *targetURLF, opts.PoolSize)
 		uri = *targetURLF
 	}
 
diff --git a/integration/setup/setup_compat.go b/integration/setup/setup_compat.go
index a647f617cbb7..f513ce450622 100644
--- a/integration/setup/setup_compat.go
+++ b/integration/setup/setup_compat.go
@@ -95,7 +95,7 @@ func SetupCompatWithOpts(tb testing.TB, opts *SetupCompatOpts) *SetupCompatResul
 	if *targetURLF == "" {
 		targetClient, _ = setupListener(tb, setupCtx, logger)
 	} else {
-		targetClient = setupClient(tb, setupCtx, *targetURLF)
+		targetClient = setupClient(tb, setupCtx, *targetURLF, 0)
 	}
 
 	// register cleanup function after setupListener registers its own to preserve full logs
@@ -103,7 +103,7 @@ func SetupCompatWithOpts(tb testing.TB, opts *SetupCompatOpts) *SetupCompatResul
 
 	targetCollections := setupCompatCollections(tb, setupCtx, targetClient, opts, *targetBackendF)
 
-	compatClient := setupClient(tb, setupCtx, *compatURLF)
+	compatClient := setupClient(tb, setupCtx, *compatURLF, 0)
 	compatCollections := setupCompatCollections(tb, setupCtx, compatClient, opts, "mongodb")
 
 	level.SetLevel(*logLevelF)
diff --git a/integration/setup/startup.go b/integration/setup/startup.go
index 124fb45714e8..019efaf50d1c 100644
--- a/integration/setup/startup.go
+++ b/integration/setup/startup.go
@@ -81,7 +81,7 @@ func Startup() {
 	must.NoError(os.MkdirAll(sqliteDir, 0o777))
 
 	if u := *targetURLF; u != "" {
-		client, err := makeClient(ctx, u)
+		client, err := makeClient(ctx, u, 0)
 		if err != nil {
 			zap.S().Fatalf("Failed to connect to target system %s: %s", u, err)
 		}
@@ -94,7 +94,7 @@ func Startup() {
 	}
 
 	if u := *compatURLF; u != "" {
-		client, err := makeClient(ctx, u)
+		client, err := makeClient(ctx, u, 0)
 		if err != nil {
 			zap.S().Fatalf("Failed to connect to compat system %s: %s", u, err)
 		}

From f9168437e7d1957d4a746b2d851366fb1236736b Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Wed, 21 Jun 2023 17:19:28 +0900
Subject: [PATCH 02/28] expose ClientOption to setup

---
 integration/query_test.go         |  2 +-
 integration/setup/client.go       | 12 +++---------
 integration/setup/listener.go     |  3 ++-
 integration/setup/setup.go        |  8 ++++++--
 integration/setup/setup_compat.go |  4 ++--
 integration/setup/startup.go      |  5 +++--
 6 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/integration/query_test.go b/integration/query_test.go
index 938dc60ef808..e6cf1c558d5e 100644
--- a/integration/query_test.go
+++ b/integration/query_test.go
@@ -951,7 +951,7 @@ func TestQueryBatchSize(t *testing.T) {
 func TestQueryCommandGetMore(t *testing.T) {
 	t.Parallel()
 	s := setup.SetupWithOpts(t, &setup.SetupOpts{
-		PoolSize: 1,
+		ClientOptions: options.Client().SetMaxPoolSize(1),
 	})
 
 	ctx, collection := s.Ctx, s.Collection
diff --git a/integration/setup/client.go b/integration/setup/client.go
index 41027c1128e6..0ebd081e580d 100644
--- a/integration/setup/client.go
+++ b/integration/setup/client.go
@@ -78,13 +78,7 @@ func mongoDBURI(tb testing.TB, opts *mongoDBURIOpts) string {
 }
 
 // makeClient returns new client for the given working MongoDB URI.
-func makeClient(ctx context.Context, uri string, poolSize uint64) (*mongo.Client, error) {
-	clientOpts := options.Client().ApplyURI(uri)
-
-	if poolSize != 0 {
-		clientOpts.SetMaxPoolSize(poolSize)
-	}
-
+func makeClient(ctx context.Context, clientOpts *options.ClientOptions) (*mongo.Client, error) {
 	clientOpts.SetMonitor(otelmongo.NewMonitor())
 
 	client, err := mongo.Connect(ctx, clientOpts)
@@ -107,7 +101,7 @@ func makeClient(ctx context.Context, uri string, poolSize uint64) (*mongo.Client
 //
 // If the connection can't be established, it panics,
 // as it doesn't make sense to proceed with other tests if we couldn't connect in one of them.
-func setupClient(tb testing.TB, ctx context.Context, uri string, poolSize uint64) *mongo.Client {
+func setupClient(tb testing.TB, ctx context.Context, clientOpts *options.ClientOptions) *mongo.Client {
 	tb.Helper()
 
 	ctx, span := otel.Tracer("").Start(ctx, "setupClient")
@@ -115,7 +109,7 @@ func setupClient(tb testing.TB, ctx context.Context, uri string, poolSize uint64
 
 	defer trace.StartRegion(ctx, "setupClient").End()
 
-	client, err := makeClient(ctx, uri, poolSize)
+	client, err := makeClient(ctx, clientOpts)
 	if err != nil {
 		tb.Error(err)
 		panic("setupClient: " + err.Error())
diff --git a/integration/setup/listener.go b/integration/setup/listener.go
index ea3600317b68..1d53ddd419a3 100644
--- a/integration/setup/listener.go
+++ b/integration/setup/listener.go
@@ -26,6 +26,7 @@ import (
 
 	"github.com/stretchr/testify/require"
 	"go.mongodb.org/mongo-driver/mongo"
+	"go.mongodb.org/mongo-driver/mongo/options"
 	"go.opentelemetry.io/otel"
 	"go.uber.org/zap"
 
@@ -213,7 +214,7 @@ func setupListener(tb testing.TB, ctx context.Context, logger *zap.Logger) (*mon
 	// those will fail the test if in-process FerretDB is not working;
 	// for example, when backend is down
 	uri := mongoDBURI(tb, &clientOpts)
-	client := setupClient(tb, ctx, uri, 0)
+	client := setupClient(tb, ctx, options.Client().ApplyURI(uri))
 
 	logger.Info("Listener started", zap.String("handler", handler), zap.String("uri", uri))
 
diff --git a/integration/setup/setup.go b/integration/setup/setup.go
index c850f6fdfc50..5f076f54e54f 100644
--- a/integration/setup/setup.go
+++ b/integration/setup/setup.go
@@ -87,7 +87,9 @@ type SetupOpts struct {
 	// Benchmark data provider. If empty, collection is not created.
 	BenchmarkProvider shareddata.BenchmarkProvider
 
-	PoolSize uint64
+	// ClientOptions specifies parameters set for client.
+	// If MongoDB URI sets the same option, this overwrites it.
+	ClientOptions *options.ClientOptions
 }
 
 // SetupResult represents setup results.
@@ -140,7 +142,9 @@ func SetupWithOpts(tb testing.TB, opts *SetupOpts) *SetupResult {
 	if *targetURLF == "" {
 		client, uri = setupListener(tb, ctx, logger)
 	} else {
-		client = setupClient(tb, ctx, *targetURLF, opts.PoolSize)
+		uriClientOpts := options.Client().ApplyURI(*targetURLF)
+		clientOpts := options.MergeClientOptions(uriClientOpts, opts.ClientOptions)
+		client = setupClient(tb, ctx, clientOpts)
 		uri = *targetURLF
 	}
 
diff --git a/integration/setup/setup_compat.go b/integration/setup/setup_compat.go
index f513ce450622..88628e53c2ac 100644
--- a/integration/setup/setup_compat.go
+++ b/integration/setup/setup_compat.go
@@ -95,7 +95,7 @@ func SetupCompatWithOpts(tb testing.TB, opts *SetupCompatOpts) *SetupCompatResul
 	if *targetURLF == "" {
 		targetClient, _ = setupListener(tb, setupCtx, logger)
 	} else {
-		targetClient = setupClient(tb, setupCtx, *targetURLF, 0)
+		targetClient = setupClient(tb, setupCtx, options.Client().ApplyURI(*targetURLF))
 	}
 
 	// register cleanup function after setupListener registers its own to preserve full logs
@@ -103,7 +103,7 @@ func SetupCompatWithOpts(tb testing.TB, opts *SetupCompatOpts) *SetupCompatResul
 
 	targetCollections := setupCompatCollections(tb, setupCtx, targetClient, opts, *targetBackendF)
 
-	compatClient := setupClient(tb, setupCtx, *compatURLF, 0)
+	compatClient := setupClient(tb, setupCtx, options.Client().ApplyURI(*compatURLF))
 	compatCollections := setupCompatCollections(tb, setupCtx, compatClient, opts, "mongodb")
 
 	level.SetLevel(*logLevelF)
diff --git a/integration/setup/startup.go b/integration/setup/startup.go
index 019efaf50d1c..f3ba2b072b0c 100644
--- a/integration/setup/startup.go
+++ b/integration/setup/startup.go
@@ -23,6 +23,7 @@ import (
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
+	"go.mongodb.org/mongo-driver/mongo/options"
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/exporters/jaeger"
 	"go.opentelemetry.io/otel/sdk/resource"
@@ -81,7 +82,7 @@ func Startup() {
 	must.NoError(os.MkdirAll(sqliteDir, 0o777))
 
 	if u := *targetURLF; u != "" {
-		client, err := makeClient(ctx, u, 0)
+		client, err := makeClient(ctx, options.Client().ApplyURI(u))
 		if err != nil {
 			zap.S().Fatalf("Failed to connect to target system %s: %s", u, err)
 		}
@@ -94,7 +95,7 @@ func Startup() {
 	}
 
 	if u := *compatURLF; u != "" {
-		client, err := makeClient(ctx, u, 0)
+		client, err := makeClient(ctx, options.Client().ApplyURI(u))
 		if err != nil {
 			zap.S().Fatalf("Failed to connect to compat system %s: %s", u, err)
 		}

From 3e00842376d12701aa0c4f1813a8c14ee20f3393 Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Fri, 23 Jun 2023 11:26:19 +0900
Subject: [PATCH 03/28] rename and comment update

---
 integration/setup/client.go | 2 +-
 integration/setup/setup.go  | 7 +++----
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/integration/setup/client.go b/integration/setup/client.go
index 0ebd081e580d..ada286351774 100644
--- a/integration/setup/client.go
+++ b/integration/setup/client.go
@@ -77,7 +77,7 @@ func mongoDBURI(tb testing.TB, opts *mongoDBURIOpts) string {
 	return u.String()
 }
 
-// makeClient returns new client for the given working MongoDB URI.
+// makeClient returns new client for the given MongoDB client options.
 func makeClient(ctx context.Context, clientOpts *options.ClientOptions) (*mongo.Client, error) {
 	clientOpts.SetMonitor(otelmongo.NewMonitor())
 
diff --git a/integration/setup/setup.go b/integration/setup/setup.go
index 5f076f54e54f..afad18538f77 100644
--- a/integration/setup/setup.go
+++ b/integration/setup/setup.go
@@ -87,8 +87,7 @@ type SetupOpts struct {
 	// Benchmark data provider. If empty, collection is not created.
 	BenchmarkProvider shareddata.BenchmarkProvider
 
-	// ClientOptions specifies parameters set for client.
-	// If MongoDB URI sets the same option, this overwrites it.
+	// ClientOptions overwrites the options set in MongoDB URI when the same option is set.
 	ClientOptions *options.ClientOptions
 }
 
@@ -142,8 +141,8 @@ func SetupWithOpts(tb testing.TB, opts *SetupOpts) *SetupResult {
 	if *targetURLF == "" {
 		client, uri = setupListener(tb, ctx, logger)
 	} else {
-		uriClientOpts := options.Client().ApplyURI(*targetURLF)
-		clientOpts := options.MergeClientOptions(uriClientOpts, opts.ClientOptions)
+		clientOpts := options.Client().ApplyURI(*targetURLF)
+		clientOpts = options.MergeClientOptions(clientOpts, opts.ClientOptions)
 		client = setupClient(tb, ctx, clientOpts)
 		uri = *targetURLF
 	}

From 04c75a614cb1a942f6f8188af737efd90e55ba0c Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Fri, 23 Jun 2023 17:22:58 +0900
Subject: [PATCH 04/28] use url.Values

---
 integration/query_test.go         |  8 +++++++-
 integration/setup/client.go       | 25 +++++++++++++++++++++----
 integration/setup/listener.go     |  3 +--
 integration/setup/setup.go        |  9 ++++-----
 integration/setup/setup_compat.go |  4 ++--
 integration/setup/startup.go      |  5 ++---
 6 files changed, 37 insertions(+), 17 deletions(-)

diff --git a/integration/query_test.go b/integration/query_test.go
index e6cf1c558d5e..99855a4fdca6 100644
--- a/integration/query_test.go
+++ b/integration/query_test.go
@@ -16,6 +16,7 @@ package integration
 
 import (
 	"math"
+	"net/url"
 	"testing"
 	"time"
 
@@ -950,8 +951,13 @@ func TestQueryBatchSize(t *testing.T) {
 
 func TestQueryCommandGetMore(t *testing.T) {
 	t.Parallel()
+
+	q := url.Values{}
+	q.Set("maxPoolSize", "1")
+	q.Set("minPoolSize", "1")
+
 	s := setup.SetupWithOpts(t, &setup.SetupOpts{
-		ClientOptions: options.Client().SetMaxPoolSize(1),
+		ExtraOptions: q,
 	})
 
 	ctx, collection := s.Ctx, s.Collection
diff --git a/integration/setup/client.go b/integration/setup/client.go
index ada286351774..6b90f71b1ef3 100644
--- a/integration/setup/client.go
+++ b/integration/setup/client.go
@@ -77,8 +77,25 @@ func mongoDBURI(tb testing.TB, opts *mongoDBURIOpts) string {
 	return u.String()
 }
 
-// makeClient returns new client for the given MongoDB client options.
-func makeClient(ctx context.Context, clientOpts *options.ClientOptions) (*mongo.Client, error) {
+// makeClient returns new client for the given MongoDB URI and extra options.
+func makeClient(ctx context.Context, uri string, extraOpts url.Values) (*mongo.Client, error) {
+	u, err := url.Parse(uri)
+	if err != nil {
+		return nil, err
+	}
+
+	q := u.Query()
+
+	for k, v := range extraOpts {
+		if len(v) == 0 {
+			continue
+		}
+
+		// when multiple values are assigned for the same key, use the first one only
+		q.Set(k, v[0])
+	}
+
+	clientOpts := options.Client().ApplyURI(u.String())
 	clientOpts.SetMonitor(otelmongo.NewMonitor())
 
 	client, err := mongo.Connect(ctx, clientOpts)
@@ -101,7 +118,7 @@ func makeClient(ctx context.Context, clientOpts *options.ClientOptions) (*mongo.
 //
 // If the connection can't be established, it panics,
 // as it doesn't make sense to proceed with other tests if we couldn't connect in one of them.
-func setupClient(tb testing.TB, ctx context.Context, clientOpts *options.ClientOptions) *mongo.Client {
+func setupClient(tb testing.TB, ctx context.Context, uri string, extraOpts url.Values) *mongo.Client {
 	tb.Helper()
 
 	ctx, span := otel.Tracer("").Start(ctx, "setupClient")
@@ -109,7 +126,7 @@ func setupClient(tb testing.TB, ctx context.Context, clientOpts *options.ClientO
 
 	defer trace.StartRegion(ctx, "setupClient").End()
 
-	client, err := makeClient(ctx, clientOpts)
+	client, err := makeClient(ctx, uri, extraOpts)
 	if err != nil {
 		tb.Error(err)
 		panic("setupClient: " + err.Error())
diff --git a/integration/setup/listener.go b/integration/setup/listener.go
index 1d53ddd419a3..06845239df26 100644
--- a/integration/setup/listener.go
+++ b/integration/setup/listener.go
@@ -26,7 +26,6 @@ import (
 
 	"github.com/stretchr/testify/require"
 	"go.mongodb.org/mongo-driver/mongo"
-	"go.mongodb.org/mongo-driver/mongo/options"
 	"go.opentelemetry.io/otel"
 	"go.uber.org/zap"
 
@@ -214,7 +213,7 @@ func setupListener(tb testing.TB, ctx context.Context, logger *zap.Logger) (*mon
 	// those will fail the test if in-process FerretDB is not working;
 	// for example, when backend is down
 	uri := mongoDBURI(tb, &clientOpts)
-	client := setupClient(tb, ctx, options.Client().ApplyURI(uri))
+	client := setupClient(tb, ctx, uri, nil)
 
 	logger.Info("Listener started", zap.String("handler", handler), zap.String("uri", uri))
 
diff --git a/integration/setup/setup.go b/integration/setup/setup.go
index afad18538f77..1858fd245518 100644
--- a/integration/setup/setup.go
+++ b/integration/setup/setup.go
@@ -19,6 +19,7 @@ import (
 	"context"
 	"flag"
 	"fmt"
+	"net/url"
 	"path/filepath"
 	"runtime/trace"
 	"strings"
@@ -87,8 +88,8 @@ type SetupOpts struct {
 	// Benchmark data provider. If empty, collection is not created.
 	BenchmarkProvider shareddata.BenchmarkProvider
 
-	// ClientOptions overwrites the options set in MongoDB URI when the same option is set.
-	ClientOptions *options.ClientOptions
+	// ExtraOptions overwrites the options set in MongoDB URI when the same option is set.
+	ExtraOptions url.Values
 }
 
 // SetupResult represents setup results.
@@ -141,9 +142,7 @@ func SetupWithOpts(tb testing.TB, opts *SetupOpts) *SetupResult {
 	if *targetURLF == "" {
 		client, uri = setupListener(tb, ctx, logger)
 	} else {
-		clientOpts := options.Client().ApplyURI(*targetURLF)
-		clientOpts = options.MergeClientOptions(clientOpts, opts.ClientOptions)
-		client = setupClient(tb, ctx, clientOpts)
+		client = setupClient(tb, ctx, *targetURLF, opts.ExtraOptions)
 		uri = *targetURLF
 	}
 
diff --git a/integration/setup/setup_compat.go b/integration/setup/setup_compat.go
index 88628e53c2ac..e556b56aada4 100644
--- a/integration/setup/setup_compat.go
+++ b/integration/setup/setup_compat.go
@@ -95,7 +95,7 @@ func SetupCompatWithOpts(tb testing.TB, opts *SetupCompatOpts) *SetupCompatResul
 	if *targetURLF == "" {
 		targetClient, _ = setupListener(tb, setupCtx, logger)
 	} else {
-		targetClient = setupClient(tb, setupCtx, options.Client().ApplyURI(*targetURLF))
+		targetClient = setupClient(tb, setupCtx, *targetURLF, nil)
 	}
 
 	// register cleanup function after setupListener registers its own to preserve full logs
@@ -103,7 +103,7 @@ func SetupCompatWithOpts(tb testing.TB, opts *SetupCompatOpts) *SetupCompatResul
 
 	targetCollections := setupCompatCollections(tb, setupCtx, targetClient, opts, *targetBackendF)
 
-	compatClient := setupClient(tb, setupCtx, options.Client().ApplyURI(*compatURLF))
+	compatClient := setupClient(tb, setupCtx, *compatURLF, nil)
 	compatCollections := setupCompatCollections(tb, setupCtx, compatClient, opts, "mongodb")
 
 	level.SetLevel(*logLevelF)
diff --git a/integration/setup/startup.go b/integration/setup/startup.go
index f3ba2b072b0c..a0308f4386ac 100644
--- a/integration/setup/startup.go
+++ b/integration/setup/startup.go
@@ -23,7 +23,6 @@ import (
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
-	"go.mongodb.org/mongo-driver/mongo/options"
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/exporters/jaeger"
 	"go.opentelemetry.io/otel/sdk/resource"
@@ -82,7 +81,7 @@ func Startup() {
 	must.NoError(os.MkdirAll(sqliteDir, 0o777))
 
 	if u := *targetURLF; u != "" {
-		client, err := makeClient(ctx, options.Client().ApplyURI(u))
+		client, err := makeClient(ctx, u, nil)
 		if err != nil {
 			zap.S().Fatalf("Failed to connect to target system %s: %s", u, err)
 		}
@@ -95,7 +94,7 @@ func Startup() {
 	}
 
 	if u := *compatURLF; u != "" {
-		client, err := makeClient(ctx, options.Client().ApplyURI(u))
+		client, err := makeClient(ctx, u, nil)
 		if err != nil {
 			zap.S().Fatalf("Failed to connect to compat system %s: %s", u, err)
 		}

From 40a511f59ad3dfdf4a841d1cb76c38b8ae7e993d Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Mon, 26 Jun 2023 10:41:29 +0900
Subject: [PATCH 05/28] tidy up

---
 integration/query_test.go   |  2 ++
 integration/setup/client.go | 10 ++++------
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/integration/query_test.go b/integration/query_test.go
index 99855a4fdca6..2eebea784d40 100644
--- a/integration/query_test.go
+++ b/integration/query_test.go
@@ -953,6 +953,8 @@ func TestQueryCommandGetMore(t *testing.T) {
 	t.Parallel()
 
 	q := url.Values{}
+
+	// Set 1 to ensure only one pool exists duration of the test
 	q.Set("maxPoolSize", "1")
 	q.Set("minPoolSize", "1")
 
diff --git a/integration/setup/client.go b/integration/setup/client.go
index 6b90f71b1ef3..660438cd9ff7 100644
--- a/integration/setup/client.go
+++ b/integration/setup/client.go
@@ -86,15 +86,13 @@ func makeClient(ctx context.Context, uri string, extraOpts url.Values) (*mongo.C
 
 	q := u.Query()
 
-	for k, v := range extraOpts {
-		if len(v) == 0 {
-			continue
+	for k, vs := range extraOpts {
+		for _, v := range vs {
+			q.Set(k, v)
 		}
-
-		// when multiple values are assigned for the same key, use the first one only
-		q.Set(k, v[0])
 	}
 
+	u.RawQuery = q.Encode()
 	clientOpts := options.Client().ApplyURI(u.String())
 	clientOpts.SetMonitor(otelmongo.NewMonitor())
 

From 2f1b735828f5b9b68842a8d4af1ce9f182c89252 Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Mon, 26 Jun 2023 11:37:40 +0900
Subject: [PATCH 06/28] add same client and different client connection tests

---
 integration/commands_diagnostic_test.go | 120 ++++++++++++++++++++++++
 1 file changed, 120 insertions(+)

diff --git a/integration/commands_diagnostic_test.go b/integration/commands_diagnostic_test.go
index 672351dbb785..747c1408a014 100644
--- a/integration/commands_diagnostic_test.go
+++ b/integration/commands_diagnostic_test.go
@@ -16,6 +16,9 @@ package integration
 
 import (
 	"net"
+	"net/url"
+	"runtime"
+	"sync"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -406,3 +409,120 @@ func TestCommandsDiagnosticWhatsMyURI(t *testing.T) {
 		assert.NotEqual(t, ports[0], ports[1])
 	}
 }
+
+func TestCommandWhatsMyURIConnection(t *testing.T) {
+	t.Parallel()
+
+	// Set 1 to ensure only one pool exists duration of the test
+	q1 := url.Values{}
+	q1.Set("maxPoolSize", "1")
+	q1.Set("minPoolSize", "1")
+
+	s := setup.SetupWithOpts(t, &setup.SetupOpts{
+		ExtraOptions: q1,
+	})
+
+	collection1 := s.Collection
+	databaseName := s.Collection.Database().Name()
+	collectionName := s.Collection.Name()
+
+	t.Run("SameClient", func(t *testing.T) {
+		num := runtime.GOMAXPROCS(-1) * 10
+		ready := make(chan struct{}, num)
+		start := make(chan struct{})
+		ports := make(chan string, num)
+
+		var wg sync.WaitGroup
+		for i := 0; i < num; i++ {
+			wg.Add(1)
+
+			go func(i int) {
+				defer wg.Done()
+
+				ready <- struct{}{}
+
+				<-start
+
+				var res bson.D
+				err := collection1.Database().RunCommand(s.Ctx, bson.D{{"whatsmyuri", int32(1)}}).Decode(&res)
+				require.NoError(t, err)
+
+				doc := ConvertDocument(t, res)
+				v, _ := doc.Get("ok")
+				resOk, ok := v.(float64)
+				require.True(t, ok)
+				assert.Equal(t, float64(1), resOk)
+
+				v, _ = doc.Get("you")
+				you, ok := v.(string)
+				require.True(t, ok)
+
+				_, port, err := net.SplitHostPort(you)
+				require.NoError(t, err)
+				assert.NotEmpty(t, port)
+				ports <- port
+			}(i)
+		}
+
+		for i := 0; i < num; i++ {
+			<-ready
+		}
+
+		close(start)
+
+		wg.Wait()
+
+		close(ports)
+
+		previousPort := <-ports
+		for port := range ports {
+			assert.Equal(t, previousPort, port)
+			previousPort = port
+		}
+	})
+
+	t.Run("DifferentClient", func(t *testing.T) {
+		u, err := url.Parse(s.MongoDBURI)
+		require.NoError(t, err)
+
+		q2 := u.Query()
+		q2.Set("maxPoolSize", "1")
+		q2.Set("minPoolSize", "1")
+		u.RawQuery = q2.Encode()
+
+		client2, err := mongo.Connect(s.Ctx, options.Client().ApplyURI(u.String()))
+		require.NoError(t, err)
+
+		defer client2.Disconnect(s.Ctx)
+
+		collection2 := client2.Database(databaseName).Collection(collectionName)
+
+		var ports []string
+
+		for _, collection := range []*mongo.Collection{collection1, collection2} {
+			var res bson.D
+			err := collection.Database().RunCommand(s.Ctx, bson.D{{"whatsmyuri", int32(1)}}).Decode(&res)
+			require.NoError(t, err)
+
+			doc := ConvertDocument(t, res)
+			v, _ := doc.Get("ok")
+			resOk, ok := v.(float64)
+			require.True(t, ok)
+			assert.Equal(t, float64(1), resOk)
+
+			v, _ = doc.Get("you")
+			you, ok := v.(string)
+			require.True(t, ok)
+
+			_, port, err := net.SplitHostPort(you)
+			require.NoError(t, err)
+			assert.NotEmpty(t, port)
+
+			ports = append(ports, port)
+		}
+
+		// compare ports from two different clients are not equal.
+		require.Equal(t, 2, len(ports))
+		assert.NotEqual(t, ports[0], ports[1])
+	})
+}

From 5d0a1476e738e1695b1102d1e570f2df47f2b51e Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Mon, 26 Jun 2023 11:55:11 +0900
Subject: [PATCH 07/28] update error message for same client tests

---
 integration/commands_diagnostic_test.go | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/integration/commands_diagnostic_test.go b/integration/commands_diagnostic_test.go
index 747c1408a014..aa1ea540a6e9 100644
--- a/integration/commands_diagnostic_test.go
+++ b/integration/commands_diagnostic_test.go
@@ -474,10 +474,13 @@ func TestCommandWhatsMyURIConnection(t *testing.T) {
 
 		close(ports)
 
-		previousPort := <-ports
+		var allPorts []string
 		for port := range ports {
-			assert.Equal(t, previousPort, port)
-			previousPort = port
+			allPorts = append(allPorts, port)
+		}
+
+		for _, port := range allPorts {
+			require.Equal(t, allPorts[0], port, "expected same client uses the same port: %s", allPorts)
 		}
 	})
 

From 9de04ca18256d2244fa9a3a83d82d892df28bce3 Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Mon, 26 Jun 2023 12:15:36 +0900
Subject: [PATCH 08/28] skip test for feature not supported by FerretDB

---
 integration/commands_diagnostic_test.go |  9 ++++++++-
 integration/query_test.go               |  3 ++-
 integration/setup/test_helpers.go       | 13 +++++++++++++
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/integration/commands_diagnostic_test.go b/integration/commands_diagnostic_test.go
index aa1ea540a6e9..412161e730e0 100644
--- a/integration/commands_diagnostic_test.go
+++ b/integration/commands_diagnostic_test.go
@@ -410,10 +410,15 @@ func TestCommandsDiagnosticWhatsMyURI(t *testing.T) {
 	}
 }
 
+// TestCommandWhatsMyURIConnection tests that a client uses the same connection for
+// all commands run by the client, and different clients use different connection.
+// The port number is used to validate if the same connection is used or not,
+// since unique port number is assigned to each client in the test setup.
 func TestCommandWhatsMyURIConnection(t *testing.T) {
 	t.Parallel()
 
-	// Set 1 to ensure only one pool exists duration of the test
+	// set 1 to ensure only one pool exists duration of the test,
+	// which forces a client to use a single pool
 	q1 := url.Values{}
 	q1.Set("maxPoolSize", "1")
 	q1.Set("minPoolSize", "1")
@@ -427,6 +432,8 @@ func TestCommandWhatsMyURIConnection(t *testing.T) {
 	collectionName := s.Collection.Name()
 
 	t.Run("SameClient", func(t *testing.T) {
+		setup.SkipExceptMongoDB(t, "https://github.com/FerretDB/FerretDB/issues/2906")
+
 		num := runtime.GOMAXPROCS(-1) * 10
 		ready := make(chan struct{}, num)
 		start := make(chan struct{})
diff --git a/integration/query_test.go b/integration/query_test.go
index 2eebea784d40..983ba5190c14 100644
--- a/integration/query_test.go
+++ b/integration/query_test.go
@@ -954,7 +954,8 @@ func TestQueryCommandGetMore(t *testing.T) {
 
 	q := url.Values{}
 
-	// Set 1 to ensure only one pool exists duration of the test
+	// set 1 to ensure only one pool exists duration of the test,
+	// which forces a client to use a single pool
 	q.Set("maxPoolSize", "1")
 	q.Set("minPoolSize", "1")
 
diff --git a/integration/setup/test_helpers.go b/integration/setup/test_helpers.go
index f16c5e8ab2e1..1b152246543f 100644
--- a/integration/setup/test_helpers.go
+++ b/integration/setup/test_helpers.go
@@ -33,6 +33,19 @@ func SkipForMongoDB(tb testing.TB, reason string) {
 	}
 }
 
+// SkipExceptMongoDB skips the current test for backends except MongoDB.
+//
+// This function should not be used lightly.
+func SkipExceptMongoDB(tb testing.TB, reason string) {
+	tb.Helper()
+
+	if *targetBackendF != "mongodb" {
+		require.NotEmpty(tb, reason, "reason must not be empty")
+
+		tb.Skipf("Skipping for MongoDB: %s.", reason)
+	}
+}
+
 // IsTigris returns true if tests are running against FerretDB with `ferretdb-tigris` backend.
 //
 // This function should not be used lightly.

From 734d5bfe05ca39556bfe93cf3fbda9d3d66d0820 Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Mon, 26 Jun 2023 12:25:24 +0900
Subject: [PATCH 09/28] comment update

---
 integration/commands_diagnostic_test.go | 5 ++---
 integration/query_test.go               | 2 +-
 integration/setup/client.go             | 1 +
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/integration/commands_diagnostic_test.go b/integration/commands_diagnostic_test.go
index 412161e730e0..657fdb1434d4 100644
--- a/integration/commands_diagnostic_test.go
+++ b/integration/commands_diagnostic_test.go
@@ -413,12 +413,12 @@ func TestCommandsDiagnosticWhatsMyURI(t *testing.T) {
 // TestCommandWhatsMyURIConnection tests that a client uses the same connection for
 // all commands run by the client, and different clients use different connection.
 // The port number is used to validate if the same connection is used or not,
-// since unique port number is assigned to each client in the test setup.
+// since unique port number is assigned to each client connection in the test setup.
 func TestCommandWhatsMyURIConnection(t *testing.T) {
 	t.Parallel()
 
 	// set 1 to ensure only one pool exists duration of the test,
-	// which forces a client to use a single pool
+	// which forces a client to use a single connection pool
 	q1 := url.Values{}
 	q1.Set("maxPoolSize", "1")
 	q1.Set("minPoolSize", "1")
@@ -531,7 +531,6 @@ func TestCommandWhatsMyURIConnection(t *testing.T) {
 			ports = append(ports, port)
 		}
 
-		// compare ports from two different clients are not equal.
 		require.Equal(t, 2, len(ports))
 		assert.NotEqual(t, ports[0], ports[1])
 	})
diff --git a/integration/query_test.go b/integration/query_test.go
index 983ba5190c14..1a5bc2a1cdcf 100644
--- a/integration/query_test.go
+++ b/integration/query_test.go
@@ -955,7 +955,7 @@ func TestQueryCommandGetMore(t *testing.T) {
 	q := url.Values{}
 
 	// set 1 to ensure only one pool exists duration of the test,
-	// which forces a client to use a single pool
+	// which forces a client to use a single connection pool
 	q.Set("maxPoolSize", "1")
 	q.Set("minPoolSize", "1")
 
diff --git a/integration/setup/client.go b/integration/setup/client.go
index 660438cd9ff7..0f09d478384c 100644
--- a/integration/setup/client.go
+++ b/integration/setup/client.go
@@ -78,6 +78,7 @@ func mongoDBURI(tb testing.TB, opts *mongoDBURIOpts) string {
 }
 
 // makeClient returns new client for the given MongoDB URI and extra options.
+// The extraOpts that comes later overwrites value for the query key.
 func makeClient(ctx context.Context, uri string, extraOpts url.Values) (*mongo.Client, error) {
 	u, err := url.Parse(uri)
 	if err != nil {

From 962ed963eabd64721b16b75809001e5c3f6386e4 Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Mon, 26 Jun 2023 13:57:46 +0900
Subject: [PATCH 10/28] run subtests in parallel

---
 integration/commands_diagnostic_test.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/integration/commands_diagnostic_test.go b/integration/commands_diagnostic_test.go
index 657fdb1434d4..751bf75bc8a1 100644
--- a/integration/commands_diagnostic_test.go
+++ b/integration/commands_diagnostic_test.go
@@ -434,6 +434,8 @@ func TestCommandWhatsMyURIConnection(t *testing.T) {
 	t.Run("SameClient", func(t *testing.T) {
 		setup.SkipExceptMongoDB(t, "https://github.com/FerretDB/FerretDB/issues/2906")
 
+		t.Parallel()
+
 		num := runtime.GOMAXPROCS(-1) * 10
 		ready := make(chan struct{}, num)
 		start := make(chan struct{})
@@ -492,6 +494,8 @@ func TestCommandWhatsMyURIConnection(t *testing.T) {
 	})
 
 	t.Run("DifferentClient", func(t *testing.T) {
+		t.Parallel()
+
 		u, err := url.Parse(s.MongoDBURI)
 		require.NoError(t, err)
 

From b0e876149305945248ae9116a8c45d33df87d6d7 Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Tue, 27 Jun 2023 13:38:35 +0900
Subject: [PATCH 11/28] test setup handles merging url with extra url.Values
 option

---
 integration/commands_diagnostic_test.go | 11 +++++------
 integration/setup/client.go             | 25 +++++--------------------
 integration/setup/listener.go           |  2 +-
 integration/setup/setup.go              | 13 ++++++++++++-
 integration/setup/setup_compat.go       |  4 ++--
 integration/setup/startup.go            |  4 ++--
 6 files changed, 27 insertions(+), 32 deletions(-)

diff --git a/integration/commands_diagnostic_test.go b/integration/commands_diagnostic_test.go
index 85a0ad18d676..af8b8e66f418 100644
--- a/integration/commands_diagnostic_test.go
+++ b/integration/commands_diagnostic_test.go
@@ -415,14 +415,13 @@ func TestCommandsDiagnosticWhatsMyURI(t *testing.T) {
 func TestCommandWhatsMyURIConnection(t *testing.T) {
 	t.Parallel()
 
-	// set 1 to ensure only one pool exists duration of the test,
+	// set minPoolSize and maxPoolSize 1 to ensure only one pool exists duration of the test,
 	// which forces a client to use a single connection pool
-	q1 := url.Values{}
-	q1.Set("maxPoolSize", "1")
-	q1.Set("minPoolSize", "1")
-
 	s := setup.SetupWithOpts(t, &setup.SetupOpts{
-		ExtraOptions: q1,
+		ExtraOptions: url.Values{
+			"minPoolSize": []string{"1"},
+			"maxPoolSize": []string{"1"},
+		},
 	})
 
 	collection1 := s.Collection
diff --git a/integration/setup/client.go b/integration/setup/client.go
index beba11911483..f0646c8b27fe 100644
--- a/integration/setup/client.go
+++ b/integration/setup/client.go
@@ -77,24 +77,9 @@ func mongoDBURI(tb testing.TB, opts *mongoDBURIOpts) string {
 	return u.String()
 }
 
-// makeClient returns new client for the given MongoDB URI and extra options.
-// The extraOpts that comes later overwrites value for the query key.
-func makeClient(ctx context.Context, uri string, extraOpts url.Values) (*mongo.Client, error) {
-	u, err := url.Parse(uri)
-	if err != nil {
-		return nil, err
-	}
-
-	q := u.Query()
-
-	for k, vs := range extraOpts {
-		for _, v := range vs {
-			q.Set(k, v)
-		}
-	}
-
-	u.RawQuery = q.Encode()
-	clientOpts := options.Client().ApplyURI(u.String())
+// makeClient returns new client for the given working MongoDB URI.
+func makeClient(ctx context.Context, uri string) (*mongo.Client, error) {
+	clientOpts := options.Client().ApplyURI(uri)
 	clientOpts.SetMonitor(otelmongo.NewMonitor())
 
 	client, err := mongo.Connect(ctx, clientOpts)
@@ -117,7 +102,7 @@ func makeClient(ctx context.Context, uri string, extraOpts url.Values) (*mongo.C
 //
 // If the connection can't be established, it panics,
 // as it doesn't make sense to proceed with other tests if we couldn't connect in one of them.
-func setupClient(tb testing.TB, ctx context.Context, uri string, extraOpts url.Values) *mongo.Client {
+func setupClient(tb testing.TB, ctx context.Context, uri string) *mongo.Client {
 	tb.Helper()
 
 	ctx, span := otel.Tracer("").Start(ctx, "setupClient")
@@ -125,7 +110,7 @@ func setupClient(tb testing.TB, ctx context.Context, uri string, extraOpts url.V
 
 	defer observability.FuncCall(ctx)()
 
-	client, err := makeClient(ctx, uri, extraOpts)
+	client, err := makeClient(ctx, uri)
 	if err != nil {
 		tb.Error(err)
 		panic("setupClient: " + err.Error())
diff --git a/integration/setup/listener.go b/integration/setup/listener.go
index a4562deb37bd..6600113202bc 100644
--- a/integration/setup/listener.go
+++ b/integration/setup/listener.go
@@ -212,7 +212,7 @@ func setupListener(tb testing.TB, ctx context.Context, logger *zap.Logger) (*mon
 	// those will fail the test if in-process FerretDB is not working;
 	// for example, when backend is down
 	uri := mongoDBURI(tb, &clientOpts)
-	client := setupClient(tb, ctx, uri, nil)
+	client := setupClient(tb, ctx, uri)
 
 	logger.Info("Listener started", zap.String("handler", handler), zap.String("uri", uri))
 
diff --git a/integration/setup/setup.go b/integration/setup/setup.go
index dd22b5ae6359..197174838408 100644
--- a/integration/setup/setup.go
+++ b/integration/setup/setup.go
@@ -143,7 +143,18 @@ func SetupWithOpts(tb testing.TB, opts *SetupOpts) *SetupResult {
 	if *targetURLF == "" {
 		client, uri = setupListener(tb, setupCtx, logger)
 	} else {
-		client = setupClient(tb, setupCtx, *targetURLF, opts.ExtraOptions)
+		u, err := url.Parse(*targetURLF)
+		require.NoError(tb, err)
+
+		q := u.Query()
+		for k, vs := range opts.ExtraOptions {
+			for _, v := range vs {
+				q.Set(k, v)
+			}
+		}
+
+		u.RawQuery = q.Encode()
+		client = setupClient(tb, setupCtx, u.String())
 		uri = *targetURLF
 	}
 
diff --git a/integration/setup/setup_compat.go b/integration/setup/setup_compat.go
index 2ea022afcac6..f6edfaccc867 100644
--- a/integration/setup/setup_compat.go
+++ b/integration/setup/setup_compat.go
@@ -96,7 +96,7 @@ func SetupCompatWithOpts(tb testing.TB, opts *SetupCompatOpts) *SetupCompatResul
 	if *targetURLF == "" {
 		targetClient, _ = setupListener(tb, setupCtx, logger)
 	} else {
-		targetClient = setupClient(tb, setupCtx, *targetURLF, nil)
+		targetClient = setupClient(tb, setupCtx, *targetURLF)
 	}
 
 	// register cleanup function after setupListener registers its own to preserve full logs
@@ -104,7 +104,7 @@ func SetupCompatWithOpts(tb testing.TB, opts *SetupCompatOpts) *SetupCompatResul
 
 	targetCollections := setupCompatCollections(tb, setupCtx, targetClient, opts, *targetBackendF)
 
-	compatClient := setupClient(tb, setupCtx, *compatURLF, nil)
+	compatClient := setupClient(tb, setupCtx, *compatURLF)
 	compatCollections := setupCompatCollections(tb, setupCtx, compatClient, opts, "mongodb")
 
 	level.SetLevel(*logLevelF)
diff --git a/integration/setup/startup.go b/integration/setup/startup.go
index a0308f4386ac..124fb45714e8 100644
--- a/integration/setup/startup.go
+++ b/integration/setup/startup.go
@@ -81,7 +81,7 @@ func Startup() {
 	must.NoError(os.MkdirAll(sqliteDir, 0o777))
 
 	if u := *targetURLF; u != "" {
-		client, err := makeClient(ctx, u, nil)
+		client, err := makeClient(ctx, u)
 		if err != nil {
 			zap.S().Fatalf("Failed to connect to target system %s: %s", u, err)
 		}
@@ -94,7 +94,7 @@ func Startup() {
 	}
 
 	if u := *compatURLF; u != "" {
-		client, err := makeClient(ctx, u, nil)
+		client, err := makeClient(ctx, u)
 		if err != nil {
 			zap.S().Fatalf("Failed to connect to compat system %s: %s", u, err)
 		}

From 733b14494898727e2001e60d1f30792eff3c56ab Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Tue, 27 Jun 2023 13:56:12 +0900
Subject: [PATCH 12/28] use stresstest.Stress

---
 integration/commands_diagnostic_test.go | 64 +++++++++----------------
 internal/util/teststress/stress.go      | 11 +++--
 2 files changed, 28 insertions(+), 47 deletions(-)

diff --git a/integration/commands_diagnostic_test.go b/integration/commands_diagnostic_test.go
index af8b8e66f418..52a08057cafa 100644
--- a/integration/commands_diagnostic_test.go
+++ b/integration/commands_diagnostic_test.go
@@ -17,8 +17,6 @@ package integration
 import (
 	"net"
 	"net/url"
-	"runtime"
-	"sync"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -31,6 +29,7 @@ import (
 	"github.com/FerretDB/FerretDB/integration/shareddata"
 	"github.com/FerretDB/FerretDB/internal/types"
 	"github.com/FerretDB/FerretDB/internal/util/must"
+	"github.com/FerretDB/FerretDB/internal/util/teststress"
 	"github.com/FerretDB/FerretDB/internal/util/testutil"
 )
 
@@ -428,55 +427,36 @@ func TestCommandWhatsMyURIConnection(t *testing.T) {
 	databaseName := s.Collection.Database().Name()
 	collectionName := s.Collection.Name()
 
-	t.Run("SameClient", func(t *testing.T) {
+	t.Run("SameClientStress", func(t *testing.T) {
 		setup.SkipExceptMongoDB(t, "https://github.com/FerretDB/FerretDB/issues/2906")
 
 		t.Parallel()
 
-		num := runtime.GOMAXPROCS(-1) * 10
-		ready := make(chan struct{}, num)
-		start := make(chan struct{})
-		ports := make(chan string, num)
+		ports := make(chan string, teststress.NumGoroutines)
 
-		var wg sync.WaitGroup
-		for i := 0; i < num; i++ {
-			wg.Add(1)
+		teststress.Stress(t, func(ready chan<- struct{}, start <-chan struct{}) {
+			ready <- struct{}{}
+			<-start
 
-			go func(i int) {
-				defer wg.Done()
-
-				ready <- struct{}{}
-
-				<-start
-
-				var res bson.D
-				err := collection1.Database().RunCommand(s.Ctx, bson.D{{"whatsmyuri", int32(1)}}).Decode(&res)
-				require.NoError(t, err)
-
-				doc := ConvertDocument(t, res)
-				v, _ := doc.Get("ok")
-				resOk, ok := v.(float64)
-				require.True(t, ok)
-				assert.Equal(t, float64(1), resOk)
-
-				v, _ = doc.Get("you")
-				you, ok := v.(string)
-				require.True(t, ok)
-
-				_, port, err := net.SplitHostPort(you)
-				require.NoError(t, err)
-				assert.NotEmpty(t, port)
-				ports <- port
-			}(i)
-		}
+			var res bson.D
+			err := collection1.Database().RunCommand(s.Ctx, bson.D{{"whatsmyuri", int32(1)}}).Decode(&res)
+			require.NoError(t, err)
 
-		for i := 0; i < num; i++ {
-			<-ready
-		}
+			doc := ConvertDocument(t, res)
+			v, _ := doc.Get("ok")
+			resOk, ok := v.(float64)
+			require.True(t, ok)
+			assert.Equal(t, float64(1), resOk)
 
-		close(start)
+			v, _ = doc.Get("you")
+			you, ok := v.(string)
+			require.True(t, ok)
 
-		wg.Wait()
+			_, port, err := net.SplitHostPort(you)
+			require.NoError(t, err)
+			assert.NotEmpty(t, port)
+			ports <- port
+		})
 
 		close(ports)
 
diff --git a/internal/util/teststress/stress.go b/internal/util/teststress/stress.go
index 972c95ef0daa..794d730224e0 100644
--- a/internal/util/teststress/stress.go
+++ b/internal/util/teststress/stress.go
@@ -23,6 +23,9 @@ import (
 	"testing"
 )
 
+// NumGoroutines is the total count of goroutines created in Stress function.
+var NumGoroutines = runtime.GOMAXPROCS(-1) * 10
+
 // Stress runs function f in multiple goroutines.
 //
 // Function f should do a needed setup, send a message to ready channel when it is ready to start,
@@ -30,15 +33,13 @@ import (
 func Stress(tb testing.TB, f func(ready chan<- struct{}, start <-chan struct{})) {
 	tb.Helper()
 
-	n := runtime.GOMAXPROCS(-1) * 10
-
 	// do a bit more work to reduce a chance that one goroutine would finish
 	// before the other one is still being created
 	var wg sync.WaitGroup
-	readyCh := make(chan struct{}, n)
+	readyCh := make(chan struct{}, NumGoroutines)
 	startCh := make(chan struct{})
 
-	for i := 0; i < n; i++ {
+	for i := 0; i < NumGoroutines; i++ {
 		wg.Add(1)
 
 		go func() {
@@ -48,7 +49,7 @@ func Stress(tb testing.TB, f func(ready chan<- struct{}, start <-chan struct{}))
 		}()
 	}
 
-	for i := 0; i < n; i++ {
+	for i := 0; i < NumGoroutines; i++ {
 		<-readyCh
 	}
 

From e6a30e5bd4105f7a0248c1f525c8db5a8e729c2d Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Tue, 27 Jun 2023 15:29:53 +0900
Subject: [PATCH 13/28] add batchSize test for find and getMore

---
 integration/query_test.go | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/integration/query_test.go b/integration/query_test.go
index 5c7c4c33b7c9..79d05453fb21 100644
--- a/integration/query_test.go
+++ b/integration/query_test.go
@@ -1192,6 +1192,34 @@ func TestQueryCommandGetMore(t *testing.T) {
 				Message: "BSON field 'getMore.collection' is missing but a required field",
 			},
 		},
+		"UnsetAllBatchSize": {
+			findBatchSize:    nil,
+			getMoreBatchSize: nil,
+			collection:       collection.Name(),
+			firstBatch:       docs[:101],
+			nextBatch:        docs[101:],
+		},
+		"UnsetFindBatchSize": {
+			findBatchSize:    nil,
+			getMoreBatchSize: 5,
+			collection:       collection.Name(),
+			firstBatch:       docs[:101],
+			nextBatch:        docs[101:106],
+		},
+		"UnsetGetMoreBatchSize": {
+			findBatchSize:    5,
+			getMoreBatchSize: nil,
+			collection:       collection.Name(),
+			firstBatch:       docs[:5],
+			nextBatch:        docs[5:],
+		},
+		"BatchSize": {
+			findBatchSize:    3,
+			getMoreBatchSize: 5,
+			collection:       collection.Name(),
+			firstBatch:       docs[:3],
+			nextBatch:        docs[3:8],
+		},
 	} {
 		name, tc := name, tc
 		t.Run(name, func(t *testing.T) {

From c6811fe723a4cfefd7e650aad245c14363d34e27 Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Tue, 27 Jun 2023 16:14:32 +0900
Subject: [PATCH 14/28] add getMore test for using different client

---
 integration/commands_diagnostic_test.go |   2 -
 integration/query_test.go               | 126 ++++++++++++++++++++++--
 2 files changed, 119 insertions(+), 9 deletions(-)

diff --git a/integration/commands_diagnostic_test.go b/integration/commands_diagnostic_test.go
index 52a08057cafa..73e8a16d2eba 100644
--- a/integration/commands_diagnostic_test.go
+++ b/integration/commands_diagnostic_test.go
@@ -428,8 +428,6 @@ func TestCommandWhatsMyURIConnection(t *testing.T) {
 	collectionName := s.Collection.Name()
 
 	t.Run("SameClientStress", func(t *testing.T) {
-		setup.SkipExceptMongoDB(t, "https://github.com/FerretDB/FerretDB/issues/2906")
-
 		t.Parallel()
 
 		ports := make(chan string, teststress.NumGoroutines)
diff --git a/integration/query_test.go b/integration/query_test.go
index 79d05453fb21..11937d46f7d2 100644
--- a/integration/query_test.go
+++ b/integration/query_test.go
@@ -30,6 +30,7 @@ import (
 
 	"github.com/FerretDB/FerretDB/integration/setup"
 	"github.com/FerretDB/FerretDB/integration/shareddata"
+	"github.com/FerretDB/FerretDB/internal/util/teststress"
 )
 
 func TestQueryBadFindType(t *testing.T) {
@@ -958,15 +959,13 @@ func TestQueryBatchSize(t *testing.T) {
 func TestQueryCommandGetMore(t *testing.T) {
 	t.Parallel()
 
-	q := url.Values{}
-
-	// set 1 to ensure only one pool exists duration of the test,
+	// set minPoolSize and maxPoolSize 1 to ensure only one pool exists duration of the test,
 	// which forces a client to use a single connection pool
-	q.Set("maxPoolSize", "1")
-	q.Set("minPoolSize", "1")
-
 	s := setup.SetupWithOpts(t, &setup.SetupOpts{
-		ExtraOptions: q,
+		ExtraOptions: url.Values{
+			"minPoolSize": []string{"1"},
+			"maxPoolSize": []string{"1"},
+		},
 	})
 
 	ctx, collection := s.Ctx, s.Collection
@@ -1316,3 +1315,116 @@ func TestQueryCommandGetMore(t *testing.T) {
 		})
 	}
 }
+
+// TestQueryCommandGetMoreConnection tests that a client uses the same connection for
+// getMore command run by the client, and different clients use different connection.
+func TestQueryCommandGetMoreConnection(t *testing.T) {
+	t.Parallel()
+
+	// set minPoolSize and maxPoolSize 1 to ensure only one pool exists duration of the test,
+	// which forces a client to use a single connection pool
+	s := setup.SetupWithOpts(t, &setup.SetupOpts{
+		ExtraOptions: url.Values{
+			"minPoolSize": []string{"1"},
+			"maxPoolSize": []string{"1"},
+		},
+	})
+
+	collection1 := s.Collection
+	databaseName := s.Collection.Database().Name()
+	collectionName := s.Collection.Name()
+
+	docs := generateDocuments(0, 110)
+	_, err := collection1.InsertMany(s.Ctx, docs)
+	require.NoError(t, err)
+
+	t.Run("SameClientStress", func(t *testing.T) {
+		t.Parallel()
+
+		teststress.Stress(t, func(ready chan<- struct{}, start <-chan struct{}) {
+			ready <- struct{}{}
+			<-start
+
+			var res bson.D
+			err := collection1.Database().RunCommand(s.Ctx,
+				bson.D{
+					{"find", collection1.Name()},
+					{"batchSize", 2},
+				}).Decode(&res)
+			require.NoError(t, err)
+
+			v, ok := res.Map()["cursor"]
+			require.True(t, ok)
+
+			cursor, ok := v.(bson.D)
+			require.True(t, ok)
+
+			cursorID := cursor.Map()["id"]
+			assert.NotNil(t, cursorID)
+
+			err = collection1.Database().RunCommand(s.Ctx, bson.D{
+				{"getMore", cursorID},
+				{"collection", collection1.Name()},
+			}).Decode(&res)
+			require.NoError(t, err)
+		})
+	})
+
+	t.Run("DifferentClient", func(t *testing.T) {
+		// error returned from using different clients are session related error,
+		// currently FerretDB does not return an error
+		setup.SkipExceptMongoDB(t, "https://github.com/FerretDB/FerretDB/issues/153")
+
+		t.Parallel()
+
+		u, err := url.Parse(s.MongoDBURI)
+		require.NoError(t, err)
+
+		q2 := u.Query()
+		q2.Set("maxPoolSize", "1")
+		q2.Set("minPoolSize", "1")
+		u.RawQuery = q2.Encode()
+
+		client2, err := mongo.Connect(s.Ctx, options.Client().ApplyURI(u.String()))
+		require.NoError(t, err)
+
+		defer client2.Disconnect(s.Ctx)
+
+		collection2 := client2.Database(databaseName).Collection(collectionName)
+
+		var res bson.D
+		err = collection1.Database().RunCommand(s.Ctx,
+			bson.D{
+				{"find", collection1.Name()},
+				{"batchSize", 2},
+			}).Decode(&res)
+		require.NoError(t, err)
+
+		v, ok := res.Map()["cursor"]
+		require.True(t, ok)
+
+		cursor, ok := v.(bson.D)
+		require.True(t, ok)
+
+		cursorID := cursor.Map()["id"]
+		assert.NotNil(t, cursorID)
+
+		err = collection2.Database().RunCommand(s.Ctx, bson.D{
+			{"getMore", cursorID},
+			{"collection", collection2.Name()},
+		}).Decode(&res)
+
+		// use AssertEqualCommandError because message cannot be compared as it contains specific session ID
+		AssertMatchesCommandError(
+			t,
+			mongo.CommandError{
+				Code: 50738,
+				Name: "Location50738",
+				Message: "Cannot run getMore on cursor 5720627396082469624, which was created in session " +
+					"95326129-ff9c-48a4-9060-464b4ea3ee06 - 47DEQpj8HBSa+/TImW+5JC\neuQeRkm5NMpJWZG3hSuFU= -  - , " +
+					"in session 9e8902e9-338c-4156-9fd8-50e5d62ac992 - 47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU= -  - ",
+			},
+			err,
+		)
+	})
+}

From 1b450c7345f33b05ac72416aeb5b413d56d84be7 Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Tue, 27 Jun 2023 16:23:41 +0900
Subject: [PATCH 15/28] update test

---
 integration/query_test.go | 37 +------------------------------------
 1 file changed, 1 insertion(+), 36 deletions(-)

diff --git a/integration/query_test.go b/integration/query_test.go
index 11937d46f7d2..111a5a4a55b4 100644
--- a/integration/query_test.go
+++ b/integration/query_test.go
@@ -30,7 +30,6 @@ import (
 
 	"github.com/FerretDB/FerretDB/integration/setup"
 	"github.com/FerretDB/FerretDB/integration/shareddata"
-	"github.com/FerretDB/FerretDB/internal/util/teststress"
 )
 
 func TestQueryBadFindType(t *testing.T) {
@@ -1316,8 +1315,6 @@ func TestQueryCommandGetMore(t *testing.T) {
 	}
 }
 
-// TestQueryCommandGetMoreConnection tests that a client uses the same connection for
-// getMore command run by the client, and different clients use different connection.
 func TestQueryCommandGetMoreConnection(t *testing.T) {
 	t.Parallel()
 
@@ -1334,42 +1331,10 @@ func TestQueryCommandGetMoreConnection(t *testing.T) {
 	databaseName := s.Collection.Database().Name()
 	collectionName := s.Collection.Name()
 
-	docs := generateDocuments(0, 110)
+	docs := generateDocuments(0, 5)
 	_, err := collection1.InsertMany(s.Ctx, docs)
 	require.NoError(t, err)
 
-	t.Run("SameClientStress", func(t *testing.T) {
-		t.Parallel()
-
-		teststress.Stress(t, func(ready chan<- struct{}, start <-chan struct{}) {
-			ready <- struct{}{}
-			<-start
-
-			var res bson.D
-			err := collection1.Database().RunCommand(s.Ctx,
-				bson.D{
-					{"find", collection1.Name()},
-					{"batchSize", 2},
-				}).Decode(&res)
-			require.NoError(t, err)
-
-			v, ok := res.Map()["cursor"]
-			require.True(t, ok)
-
-			cursor, ok := v.(bson.D)
-			require.True(t, ok)
-
-			cursorID := cursor.Map()["id"]
-			assert.NotNil(t, cursorID)
-
-			err = collection1.Database().RunCommand(s.Ctx, bson.D{
-				{"getMore", cursorID},
-				{"collection", collection1.Name()},
-			}).Decode(&res)
-			require.NoError(t, err)
-		})
-	})
-
 	t.Run("DifferentClient", func(t *testing.T) {
 		// error returned from using different clients are session related error,
 		// currently FerretDB does not return an error

From 405e8c960339279b607bb1685d5b4232e4a2b984 Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Tue, 27 Jun 2023 17:03:28 +0900
Subject: [PATCH 16/28] update commnet

---
 integration/query_test.go | 55 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 53 insertions(+), 2 deletions(-)

diff --git a/integration/query_test.go b/integration/query_test.go
index 111a5a4a55b4..c621460de888 100644
--- a/integration/query_test.go
+++ b/integration/query_test.go
@@ -1276,6 +1276,18 @@ func TestQueryCommandGetMore(t *testing.T) {
 				getMoreRest...,
 			)
 
+			// Even `find` and `getMore` use the same connection by setting `minPoolSize` and `maxPoolSize` to 1,
+			// on rare occasion it may return session error due to different session calling `find` and `getMore`.
+			// If that happens too frequently, removing t.Parallel() in subtests reduces the occurrence.
+			// Supporting session would help us understand fix it https://github.com/FerretDB/FerretDB/issues/153.
+			//
+			//mongo.CommandError{
+			//	Code: 50738,
+			//	Name: "Location50738",
+			//	Message: "Cannot run getMore on cursor 5720627396082469624, which was created in session " +
+			//		"95326129-ff9c-48a4-9060-464b4ea3ee06 - 47DEQpj8HBSa+/TImW+5JC\neuQeRkm5NMpJWZG3hSuFU= -  - , " +
+			//		"in session 9e8902e9-338c-4156-9fd8-50e5d62ac992 - 47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU= -  - ",
+			//},
 			err = collection.Database().RunCommand(ctx, getMoreCommand).Decode(&res)
 			if tc.err != nil {
 				AssertEqualAltCommandError(t, *tc.err, tc.altMessage, err)
@@ -1335,9 +1347,48 @@ func TestQueryCommandGetMoreConnection(t *testing.T) {
 	_, err := collection1.InsertMany(s.Ctx, docs)
 	require.NoError(t, err)
 
+	t.Run("SameClient", func(t *testing.T) {
+		t.Parallel()
+
+		var res bson.D
+		err = collection1.Database().RunCommand(s.Ctx,
+			bson.D{
+				{"find", collection1.Name()},
+				{"batchSize", 2},
+			}).Decode(&res)
+		require.NoError(t, err)
+
+		v, ok := res.Map()["cursor"]
+		require.True(t, ok)
+
+		cursor, ok := v.(bson.D)
+		require.True(t, ok)
+
+		cursorID := cursor.Map()["id"]
+		assert.NotNil(t, cursorID)
+
+		// Even `find` and `getMore` use the same connection by setting `minPoolSize` and `maxPoolSize` to 1,
+		// on rare occasion it may return session error due to different session calling `find` and `getMore`.
+		// If that happens too frequently, removing t.Parallel() in subtests reduces the occurrence.
+		// Supporting session would help us understand fix it https://github.com/FerretDB/FerretDB/issues/153.
+		//
+		//mongo.CommandError{
+		//	Code: 50738,
+		//	Name: "Location50738",
+		//	Message: "Cannot run getMore on cursor 5720627396082469624, which was created in session " +
+		//		"95326129-ff9c-48a4-9060-464b4ea3ee06 - 47DEQpj8HBSa+/TImW+5JC\neuQeRkm5NMpJWZG3hSuFU= -  - , " +
+		//		"in session 9e8902e9-338c-4156-9fd8-50e5d62ac992 - 47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU= -  - ",
+		//},
+		err = collection1.Database().RunCommand(s.Ctx, bson.D{
+			{"getMore", cursorID},
+			{"collection", collection1.Name()},
+		}).Decode(&res)
+		require.NoError(t, err)
+	})
+
 	t.Run("DifferentClient", func(t *testing.T) {
 		// error returned from using different clients are session related error,
-		// currently FerretDB does not return an error
+		// hence currently FerretDB does not return an error
 		setup.SkipExceptMongoDB(t, "https://github.com/FerretDB/FerretDB/issues/153")
 
 		t.Parallel()
@@ -1379,7 +1430,7 @@ func TestQueryCommandGetMoreConnection(t *testing.T) {
 			{"collection", collection2.Name()},
 		}).Decode(&res)
 
-		// use AssertEqualCommandError because message cannot be compared as it contains specific session ID
+		// use AssertEqualCommandError because message cannot be compared as it contains session ID
 		AssertMatchesCommandError(
 			t,
 			mongo.CommandError{

From 805fcb2d348f6e5d255f79d961f9efc26bdf12aa Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Tue, 27 Jun 2023 17:28:33 +0900
Subject: [PATCH 17/28] cleanup

---
 integration/commands_diagnostic_test.go |  5 -----
 integration/query_test.go               |  5 -----
 integration/setup/client.go             | 10 ++++++++++
 integration/setup/listener.go           |  8 ++++++--
 integration/setup/setup.go              |  6 +++---
 integration/setup/setup_compat.go       |  2 +-
 6 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/integration/commands_diagnostic_test.go b/integration/commands_diagnostic_test.go
index 73e8a16d2eba..fe8ed629a16c 100644
--- a/integration/commands_diagnostic_test.go
+++ b/integration/commands_diagnostic_test.go
@@ -474,11 +474,6 @@ func TestCommandWhatsMyURIConnection(t *testing.T) {
 		u, err := url.Parse(s.MongoDBURI)
 		require.NoError(t, err)
 
-		q2 := u.Query()
-		q2.Set("maxPoolSize", "1")
-		q2.Set("minPoolSize", "1")
-		u.RawQuery = q2.Encode()
-
 		client2, err := mongo.Connect(s.Ctx, options.Client().ApplyURI(u.String()))
 		require.NoError(t, err)
 
diff --git a/integration/query_test.go b/integration/query_test.go
index c621460de888..e9334f9c1daa 100644
--- a/integration/query_test.go
+++ b/integration/query_test.go
@@ -1396,11 +1396,6 @@ func TestQueryCommandGetMoreConnection(t *testing.T) {
 		u, err := url.Parse(s.MongoDBURI)
 		require.NoError(t, err)
 
-		q2 := u.Query()
-		q2.Set("maxPoolSize", "1")
-		q2.Set("minPoolSize", "1")
-		u.RawQuery = q2.Encode()
-
 		client2, err := mongo.Connect(s.Ctx, options.Client().ApplyURI(u.String()))
 		require.NoError(t, err)
 
diff --git a/integration/setup/client.go b/integration/setup/client.go
index f0646c8b27fe..e3d8ac47f06e 100644
--- a/integration/setup/client.go
+++ b/integration/setup/client.go
@@ -36,6 +36,8 @@ type mongoDBURIOpts struct {
 	hostPort       string // for TCP and TLS
 	unixSocketPath string
 	tlsAndAuth     bool
+	maxPoolSize    string
+	minPoolSize    string
 }
 
 // mongoDBURI builds MongoDB URI with given options.
@@ -65,6 +67,14 @@ func mongoDBURI(tb testing.TB, opts *mongoDBURIOpts) string {
 		user = url.UserPassword("username", "password")
 	}
 
+	if opts.maxPoolSize != "" {
+		q.Set("maxPoolSize", opts.maxPoolSize)
+	}
+
+	if opts.minPoolSize != "" {
+		q.Set("minPoolSize", opts.minPoolSize)
+	}
+
 	// TODO https://github.com/FerretDB/FerretDB/issues/1507
 	u := &url.URL{
 		Scheme:   "mongodb",
diff --git a/integration/setup/listener.go b/integration/setup/listener.go
index 2456440660ef..91c14d58faf2 100644
--- a/integration/setup/listener.go
+++ b/integration/setup/listener.go
@@ -17,6 +17,7 @@ package setup
 import (
 	"context"
 	"errors"
+	"net/url"
 	"os"
 	"path/filepath"
 	"strings"
@@ -65,7 +66,7 @@ func unixSocketPath(tb testing.TB) string {
 
 // setupListener starts in-process FerretDB server that runs until ctx is canceled.
 // It returns client and MongoDB URI of that listener.
-func setupListener(tb testing.TB, ctx context.Context, logger *zap.Logger) (*mongo.Client, string) {
+func setupListener(tb testing.TB, ctx context.Context, extraOpts url.Values, logger *zap.Logger) (*mongo.Client, string) {
 	tb.Helper()
 
 	_, span := otel.Tracer("").Start(ctx, "setupListener")
@@ -196,7 +197,10 @@ func setupListener(tb testing.TB, ctx context.Context, logger *zap.Logger) (*mon
 		<-runDone
 	})
 
-	var clientOpts mongoDBURIOpts
+	clientOpts := mongoDBURIOpts{
+		maxPoolSize: extraOpts.Get("maxPoolSize"),
+		minPoolSize: extraOpts.Get("minPoolSize"),
+	}
 
 	switch {
 	case *targetTLSF:
diff --git a/integration/setup/setup.go b/integration/setup/setup.go
index 6b28b173a228..a643f2c9a844 100644
--- a/integration/setup/setup.go
+++ b/integration/setup/setup.go
@@ -140,7 +140,7 @@ func SetupWithOpts(tb testing.TB, opts *SetupOpts) *SetupResult {
 	var uri string
 
 	if *targetURLF == "" {
-		client, uri = setupListener(tb, setupCtx, logger)
+		client, uri = setupListener(tb, setupCtx, opts.ExtraOptions, logger)
 	} else {
 		u, err := url.Parse(*targetURLF)
 		require.NoError(tb, err)
@@ -153,8 +153,8 @@ func SetupWithOpts(tb testing.TB, opts *SetupOpts) *SetupResult {
 		}
 
 		u.RawQuery = q.Encode()
-		client = setupClient(tb, setupCtx, u.String())
-		uri = *targetURLF
+		uri = u.String()
+		client = setupClient(tb, setupCtx, uri)
 	}
 
 	// register cleanup function after setupListener registers its own to preserve full logs
diff --git a/integration/setup/setup_compat.go b/integration/setup/setup_compat.go
index f6edfaccc867..5cddac647dc3 100644
--- a/integration/setup/setup_compat.go
+++ b/integration/setup/setup_compat.go
@@ -94,7 +94,7 @@ func SetupCompatWithOpts(tb testing.TB, opts *SetupCompatOpts) *SetupCompatResul
 
 	var targetClient *mongo.Client
 	if *targetURLF == "" {
-		targetClient, _ = setupListener(tb, setupCtx, logger)
+		targetClient, _ = setupListener(tb, setupCtx, nil, logger)
 	} else {
 		targetClient = setupClient(tb, setupCtx, *targetURLF)
 	}

From 9e6b8e9869d526849ed702ba7cf54ffdbefb898c Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Tue, 27 Jun 2023 18:01:21 +0900
Subject: [PATCH 18/28] do not run session related tests in parallel

---
 integration/query_test.go | 50 ++++++++++++++++++---------------------
 1 file changed, 23 insertions(+), 27 deletions(-)

diff --git a/integration/query_test.go b/integration/query_test.go
index e9334f9c1daa..f337b14767b8 100644
--- a/integration/query_test.go
+++ b/integration/query_test.go
@@ -1225,7 +1225,17 @@ func TestQueryCommandGetMore(t *testing.T) {
 				t.Skip(tc.skip)
 			}
 
-			t.Parallel()
+			// Do not run subtests in t.Parallel() to reduce the occurrence
+			// of session error. Even the same connection is used for the test
+			// by setting `minPoolSize` and `maxPoolSize` to 1, on rare occasion
+			// it returns error due to different session calling `find` and `getMore`.
+			// Supporting session would help us understand fix it
+			// https://github.com/FerretDB/FerretDB/issues/153.
+			//
+			// > Location50738
+			// > Cannot run getMore on cursor 2053655655200551971,
+			// > which was created in session 2926eea5-9775-41a3-a563-096969f1c7d5 - 47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU= -  - ,
+			// > in session 774d9ac6-b24a-4fd8-9874-f92ab1c9c8f5 - 47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU= -  -
 
 			require.NotNil(t, tc.firstBatch, "firstBatch must not be nil")
 
@@ -1276,18 +1286,6 @@ func TestQueryCommandGetMore(t *testing.T) {
 				getMoreRest...,
 			)
 
-			// Even `find` and `getMore` use the same connection by setting `minPoolSize` and `maxPoolSize` to 1,
-			// on rare occasion it may return session error due to different session calling `find` and `getMore`.
-			// If that happens too frequently, removing t.Parallel() in subtests reduces the occurrence.
-			// Supporting session would help us understand fix it https://github.com/FerretDB/FerretDB/issues/153.
-			//
-			//mongo.CommandError{
-			//	Code: 50738,
-			//	Name: "Location50738",
-			//	Message: "Cannot run getMore on cursor 5720627396082469624, which was created in session " +
-			//		"95326129-ff9c-48a4-9060-464b4ea3ee06 - 47DEQpj8HBSa+/TImW+5JC\neuQeRkm5NMpJWZG3hSuFU= -  - , " +
-			//		"in session 9e8902e9-338c-4156-9fd8-50e5d62ac992 - 47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU= -  - ",
-			//},
 			err = collection.Database().RunCommand(ctx, getMoreCommand).Decode(&res)
 			if tc.err != nil {
 				AssertEqualAltCommandError(t, *tc.err, tc.altMessage, err)
@@ -1348,7 +1346,17 @@ func TestQueryCommandGetMoreConnection(t *testing.T) {
 	require.NoError(t, err)
 
 	t.Run("SameClient", func(t *testing.T) {
-		t.Parallel()
+		// Do not run subtests in t.Parallel() to reduce the occurrence
+		// of session error. Even the same connection is used for the test
+		// by setting `minPoolSize` and `maxPoolSize` to 1, on rare occasion
+		// it returns error due to different session calling `find` and `getMore`.
+		// Supporting session would help us understand fix it
+		// https://github.com/FerretDB/FerretDB/issues/153.
+		//
+		// > Location50738
+		// > Cannot run getMore on cursor 2053655655200551971,
+		// > which was created in session 2926eea5-9775-41a3-a563-096969f1c7d5 - 47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU= -  - ,
+		// > in session 774d9ac6-b24a-4fd8-9874-f92ab1c9c8f5 - 47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU= -  -
 
 		var res bson.D
 		err = collection1.Database().RunCommand(s.Ctx,
@@ -1367,18 +1375,6 @@ func TestQueryCommandGetMoreConnection(t *testing.T) {
 		cursorID := cursor.Map()["id"]
 		assert.NotNil(t, cursorID)
 
-		// Even `find` and `getMore` use the same connection by setting `minPoolSize` and `maxPoolSize` to 1,
-		// on rare occasion it may return session error due to different session calling `find` and `getMore`.
-		// If that happens too frequently, removing t.Parallel() in subtests reduces the occurrence.
-		// Supporting session would help us understand fix it https://github.com/FerretDB/FerretDB/issues/153.
-		//
-		//mongo.CommandError{
-		//	Code: 50738,
-		//	Name: "Location50738",
-		//	Message: "Cannot run getMore on cursor 5720627396082469624, which was created in session " +
-		//		"95326129-ff9c-48a4-9060-464b4ea3ee06 - 47DEQpj8HBSa+/TImW+5JC\neuQeRkm5NMpJWZG3hSuFU= -  - , " +
-		//		"in session 9e8902e9-338c-4156-9fd8-50e5d62ac992 - 47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU= -  - ",
-		//},
 		err = collection1.Database().RunCommand(s.Ctx, bson.D{
 			{"getMore", cursorID},
 			{"collection", collection1.Name()},
@@ -1425,7 +1421,7 @@ func TestQueryCommandGetMoreConnection(t *testing.T) {
 			{"collection", collection2.Name()},
 		}).Decode(&res)
 
-		// use AssertEqualCommandError because message cannot be compared as it contains session ID
+		// use AssertMatchesCommandError because message cannot be compared as it contains session ID
 		AssertMatchesCommandError(
 			t,
 			mongo.CommandError{

From 1e1f975f53662077fe05577fa0f2e0cf66d98d78 Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Tue, 27 Jun 2023 18:46:52 +0900
Subject: [PATCH 19/28] refactor

---
 integration/setup/client.go       | 24 ++++++++++++++++++++----
 integration/setup/setup.go        | 17 +++++------------
 integration/setup/test_helpers.go |  2 +-
 3 files changed, 26 insertions(+), 17 deletions(-)

diff --git a/integration/setup/client.go b/integration/setup/client.go
index e3d8ac47f06e..d3f21e90fadd 100644
--- a/integration/setup/client.go
+++ b/integration/setup/client.go
@@ -33,6 +33,7 @@ import (
 
 // mongoDBURIOpts represents mongoDBURI's options.
 type mongoDBURIOpts struct {
+	baseURI        string
 	hostPort       string // for TCP and TLS
 	unixSocketPath string
 	tlsAndAuth     bool
@@ -45,16 +46,30 @@ func mongoDBURI(tb testing.TB, opts *mongoDBURIOpts) string {
 	tb.Helper()
 
 	var host string
+	q := make(url.Values)
 
-	if opts.hostPort != "" {
-		require.Empty(tb, opts.unixSocketPath, "both hostPort and unixSocketPath are set")
+	switch {
+	case opts.hostPort != "":
+		require.Empty(tb, opts.unixSocketPath, "only one of baseURI, hostPort or unixSocketPath should be set")
+		require.Empty(tb, opts.baseURI, "only one of baseURI, hostPort or unixSocketPath should be set")
 		host = opts.hostPort
-	} else {
+	case opts.unixSocketPath != "":
+		require.Empty(tb, opts.hostPort, "only one of baseURI, hostPort or unixSocketPath should be set")
+		require.Empty(tb, opts.baseURI, "only one of baseURI, hostPort or unixSocketPath should be set")
 		host = opts.unixSocketPath
+	case opts.baseURI != "":
+		require.Empty(tb, opts.unixSocketPath, "only one of baseURI, hostPort or unixSocketPath should be set")
+		require.Empty(tb, opts.hostPort, "only one of baseURI, hostPort or unixSocketPath should be set")
+		u, err := url.Parse(opts.baseURI)
+		require.NoError(tb, err)
+
+		host = u.Host
+		q = u.Query()
+	default:
+		require.Empty(tb, opts.unixSocketPath, "one of baseURI, hostPort or unixSocketPath should be set")
 	}
 
 	var user *url.Userinfo
-	q := make(url.Values)
 
 	if opts.tlsAndAuth {
 		require.Empty(tb, opts.unixSocketPath, "unixSocketPath cannot be used with TLS")
@@ -90,6 +105,7 @@ func mongoDBURI(tb testing.TB, opts *mongoDBURIOpts) string {
 // makeClient returns new client for the given working MongoDB URI.
 func makeClient(ctx context.Context, uri string) (*mongo.Client, error) {
 	clientOpts := options.Client().ApplyURI(uri)
+
 	clientOpts.SetMonitor(otelmongo.NewMonitor())
 
 	client, err := mongo.Connect(ctx, clientOpts)
diff --git a/integration/setup/setup.go b/integration/setup/setup.go
index a643f2c9a844..b62f67265226 100644
--- a/integration/setup/setup.go
+++ b/integration/setup/setup.go
@@ -142,18 +142,11 @@ func SetupWithOpts(tb testing.TB, opts *SetupOpts) *SetupResult {
 	if *targetURLF == "" {
 		client, uri = setupListener(tb, setupCtx, opts.ExtraOptions, logger)
 	} else {
-		u, err := url.Parse(*targetURLF)
-		require.NoError(tb, err)
-
-		q := u.Query()
-		for k, vs := range opts.ExtraOptions {
-			for _, v := range vs {
-				q.Set(k, v)
-			}
-		}
-
-		u.RawQuery = q.Encode()
-		uri = u.String()
+		uri = mongoDBURI(tb, &mongoDBURIOpts{
+			baseURI:     *targetURLF,
+			maxPoolSize: opts.ExtraOptions.Get("maxPoolSize"),
+			minPoolSize: opts.ExtraOptions.Get("minPoolSize"),
+		})
 		client = setupClient(tb, setupCtx, uri)
 	}
 
diff --git a/integration/setup/test_helpers.go b/integration/setup/test_helpers.go
index 1b152246543f..dce73c4b501d 100644
--- a/integration/setup/test_helpers.go
+++ b/integration/setup/test_helpers.go
@@ -42,7 +42,7 @@ func SkipExceptMongoDB(tb testing.TB, reason string) {
 	if *targetBackendF != "mongodb" {
 		require.NotEmpty(tb, reason, "reason must not be empty")
 
-		tb.Skipf("Skipping for MongoDB: %s.", reason)
+		tb.Skipf("Skipping for %s: %s.", *targetBackendF, reason)
 	}
 }
 

From fe31dfdd4a29d76493e0cf38ce482c67f93e5a13 Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Tue, 27 Jun 2023 18:49:26 +0900
Subject: [PATCH 20/28] fix

---
 integration/setup/client.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/integration/setup/client.go b/integration/setup/client.go
index d3f21e90fadd..7b01e67a61aa 100644
--- a/integration/setup/client.go
+++ b/integration/setup/client.go
@@ -66,7 +66,7 @@ func mongoDBURI(tb testing.TB, opts *mongoDBURIOpts) string {
 		host = u.Host
 		q = u.Query()
 	default:
-		require.Empty(tb, opts.unixSocketPath, "one of baseURI, hostPort or unixSocketPath should be set")
+		tb.Fatal("one of baseURI, hostPort or unixSocketPath should be set")
 	}
 
 	var user *url.Userinfo

From aae64c808a20eec917ab4242a536d553af534458 Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Wed, 28 Jun 2023 16:35:44 +0900
Subject: [PATCH 21/28] separate mongodburi and setup listener from extra
 options

---
 integration/setup/client.go       | 33 ++++---------------------------
 integration/setup/listener.go     |  8 ++------
 integration/setup/setup.go        | 29 +++++++++++++++++++--------
 integration/setup/setup_compat.go |  2 +-
 4 files changed, 28 insertions(+), 44 deletions(-)

diff --git a/integration/setup/client.go b/integration/setup/client.go
index 7b01e67a61aa..91db78793b08 100644
--- a/integration/setup/client.go
+++ b/integration/setup/client.go
@@ -33,12 +33,9 @@ import (
 
 // mongoDBURIOpts represents mongoDBURI's options.
 type mongoDBURIOpts struct {
-	baseURI        string
 	hostPort       string // for TCP and TLS
 	unixSocketPath string
 	tlsAndAuth     bool
-	maxPoolSize    string
-	minPoolSize    string
 }
 
 // mongoDBURI builds MongoDB URI with given options.
@@ -46,30 +43,16 @@ func mongoDBURI(tb testing.TB, opts *mongoDBURIOpts) string {
 	tb.Helper()
 
 	var host string
-	q := make(url.Values)
 
-	switch {
-	case opts.hostPort != "":
-		require.Empty(tb, opts.unixSocketPath, "only one of baseURI, hostPort or unixSocketPath should be set")
-		require.Empty(tb, opts.baseURI, "only one of baseURI, hostPort or unixSocketPath should be set")
+	if opts.hostPort != "" {
+		require.Empty(tb, opts.unixSocketPath, "both hostPort and unixSocketPath are set")
 		host = opts.hostPort
-	case opts.unixSocketPath != "":
-		require.Empty(tb, opts.hostPort, "only one of baseURI, hostPort or unixSocketPath should be set")
-		require.Empty(tb, opts.baseURI, "only one of baseURI, hostPort or unixSocketPath should be set")
+	} else {
 		host = opts.unixSocketPath
-	case opts.baseURI != "":
-		require.Empty(tb, opts.unixSocketPath, "only one of baseURI, hostPort or unixSocketPath should be set")
-		require.Empty(tb, opts.hostPort, "only one of baseURI, hostPort or unixSocketPath should be set")
-		u, err := url.Parse(opts.baseURI)
-		require.NoError(tb, err)
-
-		host = u.Host
-		q = u.Query()
-	default:
-		tb.Fatal("one of baseURI, hostPort or unixSocketPath should be set")
 	}
 
 	var user *url.Userinfo
+	q := make(url.Values)
 
 	if opts.tlsAndAuth {
 		require.Empty(tb, opts.unixSocketPath, "unixSocketPath cannot be used with TLS")
@@ -82,14 +65,6 @@ func mongoDBURI(tb testing.TB, opts *mongoDBURIOpts) string {
 		user = url.UserPassword("username", "password")
 	}
 
-	if opts.maxPoolSize != "" {
-		q.Set("maxPoolSize", opts.maxPoolSize)
-	}
-
-	if opts.minPoolSize != "" {
-		q.Set("minPoolSize", opts.minPoolSize)
-	}
-
 	// TODO https://github.com/FerretDB/FerretDB/issues/1507
 	u := &url.URL{
 		Scheme:   "mongodb",
diff --git a/integration/setup/listener.go b/integration/setup/listener.go
index 91c14d58faf2..2456440660ef 100644
--- a/integration/setup/listener.go
+++ b/integration/setup/listener.go
@@ -17,7 +17,6 @@ package setup
 import (
 	"context"
 	"errors"
-	"net/url"
 	"os"
 	"path/filepath"
 	"strings"
@@ -66,7 +65,7 @@ func unixSocketPath(tb testing.TB) string {
 
 // setupListener starts in-process FerretDB server that runs until ctx is canceled.
 // It returns client and MongoDB URI of that listener.
-func setupListener(tb testing.TB, ctx context.Context, extraOpts url.Values, logger *zap.Logger) (*mongo.Client, string) {
+func setupListener(tb testing.TB, ctx context.Context, logger *zap.Logger) (*mongo.Client, string) {
 	tb.Helper()
 
 	_, span := otel.Tracer("").Start(ctx, "setupListener")
@@ -197,10 +196,7 @@ func setupListener(tb testing.TB, ctx context.Context, extraOpts url.Values, log
 		<-runDone
 	})
 
-	clientOpts := mongoDBURIOpts{
-		maxPoolSize: extraOpts.Get("maxPoolSize"),
-		minPoolSize: extraOpts.Get("minPoolSize"),
-	}
+	var clientOpts mongoDBURIOpts
 
 	switch {
 	case *targetTLSF:
diff --git a/integration/setup/setup.go b/integration/setup/setup.go
index b62f67265226..513e07d60065 100644
--- a/integration/setup/setup.go
+++ b/integration/setup/setup.go
@@ -137,16 +137,29 @@ func SetupWithOpts(tb testing.TB, opts *SetupOpts) *SetupResult {
 	logger := testutil.LevelLogger(tb, level)
 
 	var client *mongo.Client
-	var uri string
+	uri := *targetURLF
 
 	if *targetURLF == "" {
-		client, uri = setupListener(tb, setupCtx, opts.ExtraOptions, logger)
-	} else {
-		uri = mongoDBURI(tb, &mongoDBURIOpts{
-			baseURI:     *targetURLF,
-			maxPoolSize: opts.ExtraOptions.Get("maxPoolSize"),
-			minPoolSize: opts.ExtraOptions.Get("minPoolSize"),
-		})
+		client, uri = setupListener(tb, setupCtx, logger)
+	}
+
+	if opts.ExtraOptions != nil || *targetURLF != "" {
+		u, err := url.Parse(uri)
+		require.NoError(tb, err)
+
+		q := u.Query()
+		for k, vs := range opts.ExtraOptions {
+			for _, v := range vs {
+				q.Set(k, v)
+			}
+		}
+
+		u.RawQuery = q.Encode()
+		uri = u.String()
+
+		// If ExtraOptions is set for in-process FerretDB, two clients are created.
+		// setupListener creates a client to check in-process FerretDB,
+		// and this client used for tests with extra options.
 		client = setupClient(tb, setupCtx, uri)
 	}
 
diff --git a/integration/setup/setup_compat.go b/integration/setup/setup_compat.go
index 5cddac647dc3..f6edfaccc867 100644
--- a/integration/setup/setup_compat.go
+++ b/integration/setup/setup_compat.go
@@ -94,7 +94,7 @@ func SetupCompatWithOpts(tb testing.TB, opts *SetupCompatOpts) *SetupCompatResul
 
 	var targetClient *mongo.Client
 	if *targetURLF == "" {
-		targetClient, _ = setupListener(tb, setupCtx, nil, logger)
+		targetClient, _ = setupListener(tb, setupCtx, logger)
 	} else {
 		targetClient = setupClient(tb, setupCtx, *targetURLF)
 	}

From a22d37c88b4510887faae8aaa3b2624037c29cbc Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Wed, 28 Jun 2023 16:48:56 +0900
Subject: [PATCH 22/28] refactoring func name

---
 integration/setup/client.go   |  8 ++++----
 integration/setup/listener.go | 12 ++++++------
 integration/setup/setup.go    |  2 +-
 3 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/integration/setup/client.go b/integration/setup/client.go
index 91db78793b08..3c7220c773dd 100644
--- a/integration/setup/client.go
+++ b/integration/setup/client.go
@@ -31,15 +31,15 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/observability"
 )
 
-// mongoDBURIOpts represents mongoDBURI's options.
-type mongoDBURIOpts struct {
+// buildURIForInProcessFerretDBOpts represents buildURIForInProcessFerretDB's options.
+type buildURIForInProcessFerretDBOpts struct {
 	hostPort       string // for TCP and TLS
 	unixSocketPath string
 	tlsAndAuth     bool
 }
 
-// mongoDBURI builds MongoDB URI with given options.
-func mongoDBURI(tb testing.TB, opts *mongoDBURIOpts) string {
+// buildURIForInProcessFerretDB is used to construct URI from options obtained from in-process FerretDB.
+func buildURIForInProcessFerretDB(tb testing.TB, opts *buildURIForInProcessFerretDBOpts) string {
 	tb.Helper()
 
 	var host string
diff --git a/integration/setup/listener.go b/integration/setup/listener.go
index 2456440660ef..f8d1be7eb8bc 100644
--- a/integration/setup/listener.go
+++ b/integration/setup/listener.go
@@ -196,21 +196,21 @@ func setupListener(tb testing.TB, ctx context.Context, logger *zap.Logger) (*mon
 		<-runDone
 	})
 
-	var clientOpts mongoDBURIOpts
+	var opts buildURIForInProcessFerretDBOpts
 
 	switch {
 	case *targetTLSF:
-		clientOpts.hostPort = l.TLSAddr().String()
-		clientOpts.tlsAndAuth = true
+		opts.hostPort = l.TLSAddr().String()
+		opts.tlsAndAuth = true
 	case *targetUnixSocketF:
-		clientOpts.unixSocketPath = l.UnixAddr().String()
+		opts.unixSocketPath = l.UnixAddr().String()
 	default:
-		clientOpts.hostPort = l.TCPAddr().String()
+		opts.hostPort = l.TCPAddr().String()
 	}
 
 	// those will fail the test if in-process FerretDB is not working;
 	// for example, when backend is down
-	uri := mongoDBURI(tb, &clientOpts)
+	uri := buildURIForInProcessFerretDB(tb, &opts)
 	client := setupClient(tb, ctx, uri)
 
 	logger.Info("Listener started", zap.String("handler", handler), zap.String("uri", uri))
diff --git a/integration/setup/setup.go b/integration/setup/setup.go
index 513e07d60065..a099c650d650 100644
--- a/integration/setup/setup.go
+++ b/integration/setup/setup.go
@@ -158,7 +158,7 @@ func SetupWithOpts(tb testing.TB, opts *SetupOpts) *SetupResult {
 		uri = u.String()
 
 		// If ExtraOptions is set for in-process FerretDB, two clients are created.
-		// setupListener creates a client to check in-process FerretDB,
+		// setupListener creates a client to check in-process FerretDB parameters,
 		// and this client used for tests with extra options.
 		client = setupClient(tb, setupCtx, uri)
 	}

From 1a65aac4b538a7cfcf0260ca1404298360cd2622 Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Wed, 28 Jun 2023 18:13:28 +0900
Subject: [PATCH 23/28] update comments and rename

---
 integration/commands_diagnostic_test.go | 22 +++-----
 integration/query_test.go               | 75 ++++++++++++++-----------
 integration/setup/setup.go              |  2 +-
 3 files changed, 50 insertions(+), 49 deletions(-)

diff --git a/integration/commands_diagnostic_test.go b/integration/commands_diagnostic_test.go
index fe8ed629a16c..b9374e9d43a6 100644
--- a/integration/commands_diagnostic_test.go
+++ b/integration/commands_diagnostic_test.go
@@ -407,19 +407,17 @@ func TestCommandsDiagnosticWhatsMyURI(t *testing.T) {
 	}
 }
 
-// TestCommandWhatsMyURIConnection tests that a client uses the same connection for
-// all commands run by the client, and different clients use different connection.
-// The port number is used to validate if the same connection is used or not,
-// since unique port number is assigned to each client connection in the test setup.
+// TestCommandWhatsMyURIConnection tests that integration test setup applies
+// minPoolSize, maxPoolSize and maxIdleTimeMS correctly to the driver.
 func TestCommandWhatsMyURIConnection(t *testing.T) {
 	t.Parallel()
 
-	// set minPoolSize and maxPoolSize 1 to ensure only one pool exists duration of the test,
-	// which forces a client to use a single connection pool
+	// single connection is used by the client created from setup
 	s := setup.SetupWithOpts(t, &setup.SetupOpts{
 		ExtraOptions: url.Values{
-			"minPoolSize": []string{"1"},
-			"maxPoolSize": []string{"1"},
+			"minPoolSize":   []string{"1"},
+			"maxPoolSize":   []string{"1"},
+			"maxIdleTimeMS": []string{"0"},
 		},
 	})
 
@@ -458,13 +456,9 @@ func TestCommandWhatsMyURIConnection(t *testing.T) {
 
 		close(ports)
 
-		var allPorts []string
+		firstPort := <-ports
 		for port := range ports {
-			allPorts = append(allPorts, port)
-		}
-
-		for _, port := range allPorts {
-			require.Equal(t, allPorts[0], port, "expected same client uses the same port: %s", allPorts)
+			require.Equal(t, firstPort, port, "expected same client to use the same port")
 		}
 	})
 
diff --git a/integration/query_test.go b/integration/query_test.go
index f337b14767b8..51bf9b235e69 100644
--- a/integration/query_test.go
+++ b/integration/query_test.go
@@ -958,12 +958,12 @@ func TestQueryBatchSize(t *testing.T) {
 func TestQueryCommandGetMore(t *testing.T) {
 	t.Parallel()
 
-	// set minPoolSize and maxPoolSize 1 to ensure only one pool exists duration of the test,
-	// which forces a client to use a single connection pool
+	// single connection is used by the client created from setup
 	s := setup.SetupWithOpts(t, &setup.SetupOpts{
 		ExtraOptions: url.Values{
-			"minPoolSize": []string{"1"},
-			"maxPoolSize": []string{"1"},
+			"minPoolSize":   []string{"1"},
+			"maxPoolSize":   []string{"1"},
+			"maxIdleTimeMS": []string{"0"},
 		},
 	})
 
@@ -1225,10 +1225,8 @@ func TestQueryCommandGetMore(t *testing.T) {
 				t.Skip(tc.skip)
 			}
 
-			// Do not run subtests in t.Parallel() to reduce the occurrence
-			// of session error. Even the same connection is used for the test
-			// by setting `minPoolSize` and `maxPoolSize` to 1, on rare occasion
-			// it returns error due to different session calling `find` and `getMore`.
+			// Do not run subtests in t.Parallel() to eliminate the occurrence
+			// of session error.
 			// Supporting session would help us understand fix it
 			// https://github.com/FerretDB/FerretDB/issues/153.
 			//
@@ -1328,28 +1326,27 @@ func TestQueryCommandGetMore(t *testing.T) {
 func TestQueryCommandGetMoreConnection(t *testing.T) {
 	t.Parallel()
 
-	// set minPoolSize and maxPoolSize 1 to ensure only one pool exists duration of the test,
-	// which forces a client to use a single connection pool
+	// single connection is used by the client created from setup
 	s := setup.SetupWithOpts(t, &setup.SetupOpts{
 		ExtraOptions: url.Values{
-			"minPoolSize": []string{"1"},
-			"maxPoolSize": []string{"1"},
+			"minPoolSize":   []string{"1"},
+			"maxPoolSize":   []string{"1"},
+			"maxIdleTimeMS": []string{"0"},
 		},
 	})
 
+	ctx := s.Ctx
 	collection1 := s.Collection
 	databaseName := s.Collection.Database().Name()
 	collectionName := s.Collection.Name()
 
 	docs := generateDocuments(0, 5)
-	_, err := collection1.InsertMany(s.Ctx, docs)
+	_, err := collection1.InsertMany(ctx, docs)
 	require.NoError(t, err)
 
 	t.Run("SameClient", func(t *testing.T) {
-		// Do not run subtests in t.Parallel() to reduce the occurrence
-		// of session error. Even the same connection is used for the test
-		// by setting `minPoolSize` and `maxPoolSize` to 1, on rare occasion
-		// it returns error due to different session calling `find` and `getMore`.
+		// Do not run subtests in t.Parallel() to eliminate the occurrence
+		// of session error.
 		// Supporting session would help us understand fix it
 		// https://github.com/FerretDB/FerretDB/issues/153.
 		//
@@ -1359,11 +1356,13 @@ func TestQueryCommandGetMoreConnection(t *testing.T) {
 		// > in session 774d9ac6-b24a-4fd8-9874-f92ab1c9c8f5 - 47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU= -  -
 
 		var res bson.D
-		err = collection1.Database().RunCommand(s.Ctx,
+		err = collection1.Database().RunCommand(
+			ctx,
 			bson.D{
 				{"find", collection1.Name()},
 				{"batchSize", 2},
-			}).Decode(&res)
+			},
+		).Decode(&res)
 		require.NoError(t, err)
 
 		v, ok := res.Map()["cursor"]
@@ -1375,36 +1374,41 @@ func TestQueryCommandGetMoreConnection(t *testing.T) {
 		cursorID := cursor.Map()["id"]
 		assert.NotNil(t, cursorID)
 
-		err = collection1.Database().RunCommand(s.Ctx, bson.D{
-			{"getMore", cursorID},
-			{"collection", collection1.Name()},
-		}).Decode(&res)
+		err = collection1.Database().RunCommand(
+			ctx,
+			bson.D{
+				{"getMore", cursorID},
+				{"collection", collection1.Name()},
+			},
+		).Decode(&res)
 		require.NoError(t, err)
 	})
 
 	t.Run("DifferentClient", func(t *testing.T) {
-		// error returned from using different clients are session related error,
-		// hence currently FerretDB does not return an error
+		// The error returned from MongoDB is a session error, FerretDB does not
+		// return an error because db, collection and username are the same.
 		setup.SkipExceptMongoDB(t, "https://github.com/FerretDB/FerretDB/issues/153")
 
-		t.Parallel()
+		// Do not run subtest in t.Parallel() to avoid breaking when another subtest is added.
 
 		u, err := url.Parse(s.MongoDBURI)
 		require.NoError(t, err)
 
-		client2, err := mongo.Connect(s.Ctx, options.Client().ApplyURI(u.String()))
+		client2, err := mongo.Connect(ctx, options.Client().ApplyURI(u.String()))
 		require.NoError(t, err)
 
-		defer client2.Disconnect(s.Ctx)
+		defer client2.Disconnect(ctx)
 
 		collection2 := client2.Database(databaseName).Collection(collectionName)
 
 		var res bson.D
-		err = collection1.Database().RunCommand(s.Ctx,
+		err = collection1.Database().RunCommand(
+			ctx,
 			bson.D{
 				{"find", collection1.Name()},
 				{"batchSize", 2},
-			}).Decode(&res)
+			},
+		).Decode(&res)
 		require.NoError(t, err)
 
 		v, ok := res.Map()["cursor"]
@@ -1416,10 +1420,13 @@ func TestQueryCommandGetMoreConnection(t *testing.T) {
 		cursorID := cursor.Map()["id"]
 		assert.NotNil(t, cursorID)
 
-		err = collection2.Database().RunCommand(s.Ctx, bson.D{
-			{"getMore", cursorID},
-			{"collection", collection2.Name()},
-		}).Decode(&res)
+		err = collection2.Database().RunCommand(
+			ctx,
+			bson.D{
+				{"getMore", cursorID},
+				{"collection", collection2.Name()},
+			},
+		).Decode(&res)
 
 		// use AssertMatchesCommandError because message cannot be compared as it contains session ID
 		AssertMatchesCommandError(
diff --git a/integration/setup/setup.go b/integration/setup/setup.go
index a099c650d650..e57a083c6f51 100644
--- a/integration/setup/setup.go
+++ b/integration/setup/setup.go
@@ -88,7 +88,7 @@ type SetupOpts struct {
 	// Benchmark data provider. If empty, collection is not created.
 	BenchmarkProvider shareddata.BenchmarkProvider
 
-	// ExtraOptions overwrites the options set in MongoDB URI when the same option is set.
+	// ExtraOptions sets the options in MongoDB URI, when the option exists it overwrites that option.
 	ExtraOptions url.Values
 }
 

From 0e7adb8ccae8409c1ec848a23c17cf251fa2bddd Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Wed, 28 Jun 2023 18:31:40 +0900
Subject: [PATCH 24/28] cleanup

---
 integration/commands_diagnostic_test.go | 2 +-
 integration/query_test.go               | 6 +++---
 integration/setup/client.go             | 8 ++++----
 integration/setup/listener.go           | 4 ++--
 integration/setup/setup.go              | 6 +++---
 5 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/integration/commands_diagnostic_test.go b/integration/commands_diagnostic_test.go
index b9374e9d43a6..3957c7909c64 100644
--- a/integration/commands_diagnostic_test.go
+++ b/integration/commands_diagnostic_test.go
@@ -412,7 +412,7 @@ func TestCommandsDiagnosticWhatsMyURI(t *testing.T) {
 func TestCommandWhatsMyURIConnection(t *testing.T) {
 	t.Parallel()
 
-	// single connection is used by the client created from setup
+	// options are applied to create a client that uses single connection pool
 	s := setup.SetupWithOpts(t, &setup.SetupOpts{
 		ExtraOptions: url.Values{
 			"minPoolSize":   []string{"1"},
diff --git a/integration/query_test.go b/integration/query_test.go
index 51bf9b235e69..d116f4a7b4fc 100644
--- a/integration/query_test.go
+++ b/integration/query_test.go
@@ -958,7 +958,7 @@ func TestQueryBatchSize(t *testing.T) {
 func TestQueryCommandGetMore(t *testing.T) {
 	t.Parallel()
 
-	// single connection is used by the client created from setup
+	// options are applied to create a client that uses single connection pool
 	s := setup.SetupWithOpts(t, &setup.SetupOpts{
 		ExtraOptions: url.Values{
 			"minPoolSize":   []string{"1"},
@@ -1326,7 +1326,7 @@ func TestQueryCommandGetMore(t *testing.T) {
 func TestQueryCommandGetMoreConnection(t *testing.T) {
 	t.Parallel()
 
-	// single connection is used by the client created from setup
+	// options are applied to create a client that uses single connection pool
 	s := setup.SetupWithOpts(t, &setup.SetupOpts{
 		ExtraOptions: url.Values{
 			"minPoolSize":   []string{"1"},
@@ -1389,7 +1389,7 @@ func TestQueryCommandGetMoreConnection(t *testing.T) {
 		// return an error because db, collection and username are the same.
 		setup.SkipExceptMongoDB(t, "https://github.com/FerretDB/FerretDB/issues/153")
 
-		// Do not run subtest in t.Parallel() to avoid breaking when another subtest is added.
+		// do not run subtest in parallel to avoid breaking another parallel subtest
 
 		u, err := url.Parse(s.MongoDBURI)
 		require.NoError(t, err)
diff --git a/integration/setup/client.go b/integration/setup/client.go
index 3c7220c773dd..faea3e18c59b 100644
--- a/integration/setup/client.go
+++ b/integration/setup/client.go
@@ -31,15 +31,15 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/observability"
 )
 
-// buildURIForInProcessFerretDBOpts represents buildURIForInProcessFerretDB's options.
-type buildURIForInProcessFerretDBOpts struct {
+// buildInProcessFerretDBURIOpts represents buildInProcessFerretDBURI's options.
+type buildInProcessFerretDBURIOpts struct {
 	hostPort       string // for TCP and TLS
 	unixSocketPath string
 	tlsAndAuth     bool
 }
 
-// buildURIForInProcessFerretDB is used to construct URI from options obtained from in-process FerretDB.
-func buildURIForInProcessFerretDB(tb testing.TB, opts *buildURIForInProcessFerretDBOpts) string {
+// buildInProcessFerretDBURI is used to construct URI from options obtained from in-process FerretDB.
+func buildInProcessFerretDBURI(tb testing.TB, opts *buildInProcessFerretDBURIOpts) string {
 	tb.Helper()
 
 	var host string
diff --git a/integration/setup/listener.go b/integration/setup/listener.go
index f8d1be7eb8bc..fde71dff90c1 100644
--- a/integration/setup/listener.go
+++ b/integration/setup/listener.go
@@ -196,7 +196,7 @@ func setupListener(tb testing.TB, ctx context.Context, logger *zap.Logger) (*mon
 		<-runDone
 	})
 
-	var opts buildURIForInProcessFerretDBOpts
+	var opts buildInProcessFerretDBURIOpts
 
 	switch {
 	case *targetTLSF:
@@ -210,7 +210,7 @@ func setupListener(tb testing.TB, ctx context.Context, logger *zap.Logger) (*mon
 
 	// those will fail the test if in-process FerretDB is not working;
 	// for example, when backend is down
-	uri := buildURIForInProcessFerretDB(tb, &opts)
+	uri := buildInProcessFerretDBURI(tb, &opts)
 	client := setupClient(tb, ctx, uri)
 
 	logger.Info("Listener started", zap.String("handler", handler), zap.String("uri", uri))
diff --git a/integration/setup/setup.go b/integration/setup/setup.go
index e57a083c6f51..01fa6ffa1a92 100644
--- a/integration/setup/setup.go
+++ b/integration/setup/setup.go
@@ -157,9 +157,9 @@ func SetupWithOpts(tb testing.TB, opts *SetupOpts) *SetupResult {
 		u.RawQuery = q.Encode()
 		uri = u.String()
 
-		// If ExtraOptions is set for in-process FerretDB, two clients are created.
-		// setupListener creates a client to check in-process FerretDB parameters,
-		// and this client used for tests with extra options.
+		// If ExtraOptions is set for in-process FerretDB, two clients are created
+		// on purpose. setupListener creates a client to check in-process FerretDB
+		// options, and this client is created with extra options used for tests.
 		client = setupClient(tb, setupCtx, uri)
 	}
 

From c2397d2c880de1e5ee2b03c4b70fba90c2039c44 Mon Sep 17 00:00:00 2001
From: Chi Fujii <chi.fujii@ferretdb.io>
Date: Wed, 28 Jun 2023 19:58:48 +0900
Subject: [PATCH 25/28] fix new linter

---
 integration/query_test.go  | 21 +++++++++++++--------
 integration/setup/setup.go |  1 +
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/integration/query_test.go b/integration/query_test.go
index d116f4a7b4fc..daafc5d63d8f 100644
--- a/integration/query_test.go
+++ b/integration/query_test.go
@@ -30,6 +30,7 @@ import (
 
 	"github.com/FerretDB/FerretDB/integration/setup"
 	"github.com/FerretDB/FerretDB/integration/shareddata"
+	"github.com/FerretDB/FerretDB/internal/types"
 )
 
 func TestQueryBadFindType(t *testing.T) {
@@ -1365,13 +1366,15 @@ func TestQueryCommandGetMoreConnection(t *testing.T) {
 		).Decode(&res)
 		require.NoError(t, err)
 
-		v, ok := res.Map()["cursor"]
-		require.True(t, ok)
+		doc := ConvertDocument(t, res)
+
+		v, _ := doc.Get("cursor")
+		require.NotNil(t, v)
 
-		cursor, ok := v.(bson.D)
+		cursor, ok := v.(*types.Document)
 		require.True(t, ok)
 
-		cursorID := cursor.Map()["id"]
+		cursorID, _ := cursor.Get("id")
 		assert.NotNil(t, cursorID)
 
 		err = collection1.Database().RunCommand(
@@ -1411,13 +1414,15 @@ func TestQueryCommandGetMoreConnection(t *testing.T) {
 		).Decode(&res)
 		require.NoError(t, err)
 
-		v, ok := res.Map()["cursor"]
-		require.True(t, ok)
+		doc := ConvertDocument(t, res)
+
+		v, _ := doc.Get("cursor")
+		require.NotNil(t, v)
 
-		cursor, ok := v.(bson.D)
+		cursor, ok := v.(*types.Document)
 		require.True(t, ok)
 
-		cursorID := cursor.Map()["id"]
+		cursorID, _ := cursor.Get("id")
 		assert.NotNil(t, cursorID)
 
 		err = collection2.Database().RunCommand(
diff --git a/integration/setup/setup.go b/integration/setup/setup.go
index 01fa6ffa1a92..953b3f9eef2b 100644
--- a/integration/setup/setup.go
+++ b/integration/setup/setup.go
@@ -148,6 +148,7 @@ func SetupWithOpts(tb testing.TB, opts *SetupOpts) *SetupResult {
 		require.NoError(tb, err)
 
 		q := u.Query()
+
 		for k, vs := range opts.ExtraOptions {
 			for _, v := range vs {
 				q.Set(k, v)

From d5df4e013837af622e456128815c4a3284442c7f Mon Sep 17 00:00:00 2001
From: Alexey Palazhchenko <alexey.palazhchenko@ferretdb.io>
Date: Wed, 28 Jun 2023 22:09:12 +0400
Subject: [PATCH 26/28] Tweak comment

---
 integration/commands_diagnostic_test.go | 1 +
 1 file changed, 1 insertion(+)

diff --git a/integration/commands_diagnostic_test.go b/integration/commands_diagnostic_test.go
index 3957c7909c64..b24a0242cf90 100644
--- a/integration/commands_diagnostic_test.go
+++ b/integration/commands_diagnostic_test.go
@@ -409,6 +409,7 @@ func TestCommandsDiagnosticWhatsMyURI(t *testing.T) {
 
 // TestCommandWhatsMyURIConnection tests that integration test setup applies
 // minPoolSize, maxPoolSize and maxIdleTimeMS correctly to the driver.
+// It also tests that the driver behaves like we think it should.
 func TestCommandWhatsMyURIConnection(t *testing.T) {
 	t.Parallel()
 

From 17db130f810e91322a1fc7141c8bcaffce159c20 Mon Sep 17 00:00:00 2001
From: Alexey Palazhchenko <alexey.palazhchenko@ferretdb.io>
Date: Wed, 28 Jun 2023 22:27:56 +0400
Subject: [PATCH 27/28] Simplify

---
 integration/setup/client.go       | 48 --------------------
 integration/setup/listener.go     | 73 +++++++++++++++++++++----------
 integration/setup/setup.go        | 16 +++----
 integration/setup/setup_compat.go |  3 +-
 4 files changed, 59 insertions(+), 81 deletions(-)

diff --git a/integration/setup/client.go b/integration/setup/client.go
index faea3e18c59b..82d1bb58b21d 100644
--- a/integration/setup/client.go
+++ b/integration/setup/client.go
@@ -16,8 +16,6 @@ package setup
 
 import (
 	"context"
-	"net/url"
-	"path/filepath"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -31,52 +29,6 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/observability"
 )
 
-// buildInProcessFerretDBURIOpts represents buildInProcessFerretDBURI's options.
-type buildInProcessFerretDBURIOpts struct {
-	hostPort       string // for TCP and TLS
-	unixSocketPath string
-	tlsAndAuth     bool
-}
-
-// buildInProcessFerretDBURI is used to construct URI from options obtained from in-process FerretDB.
-func buildInProcessFerretDBURI(tb testing.TB, opts *buildInProcessFerretDBURIOpts) string {
-	tb.Helper()
-
-	var host string
-
-	if opts.hostPort != "" {
-		require.Empty(tb, opts.unixSocketPath, "both hostPort and unixSocketPath are set")
-		host = opts.hostPort
-	} else {
-		host = opts.unixSocketPath
-	}
-
-	var user *url.Userinfo
-	q := make(url.Values)
-
-	if opts.tlsAndAuth {
-		require.Empty(tb, opts.unixSocketPath, "unixSocketPath cannot be used with TLS")
-
-		// we don't separate TLS and auth just for simplicity of our test configurations
-		q.Set("tls", "true")
-		q.Set("tlsCertificateKeyFile", filepath.Join(CertsRoot, "client.pem"))
-		q.Set("tlsCaFile", filepath.Join(CertsRoot, "rootCA-cert.pem"))
-		q.Set("authMechanism", "PLAIN")
-		user = url.UserPassword("username", "password")
-	}
-
-	// TODO https://github.com/FerretDB/FerretDB/issues/1507
-	u := &url.URL{
-		Scheme:   "mongodb",
-		Host:     host,
-		Path:     "/",
-		User:     user,
-		RawQuery: q.Encode(),
-	}
-
-	return u.String()
-}
-
 // makeClient returns new client for the given working MongoDB URI.
 func makeClient(ctx context.Context, uri string) (*mongo.Client, error) {
 	clientOpts := options.Client().ApplyURI(uri)
diff --git a/integration/setup/listener.go b/integration/setup/listener.go
index fde71dff90c1..7f33f17d5cdd 100644
--- a/integration/setup/listener.go
+++ b/integration/setup/listener.go
@@ -17,6 +17,7 @@ package setup
 import (
 	"context"
 	"errors"
+	"net/url"
 	"os"
 	"path/filepath"
 	"strings"
@@ -24,7 +25,6 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/require"
-	"go.mongodb.org/mongo-driver/mongo"
 	"go.opentelemetry.io/otel"
 	"go.uber.org/zap"
 
@@ -63,9 +63,48 @@ func unixSocketPath(tb testing.TB) string {
 	return f.Name()
 }
 
+// listenerMongoDBURI builds MongoDB URI for in-process FerretDB.
+func listenerMongoDBURI(tb testing.TB, hostPort, unixSocketPath string, tlsAndAuth bool) string {
+	tb.Helper()
+
+	var host string
+
+	if hostPort != "" {
+		require.Empty(tb, unixSocketPath, "both hostPort and unixSocketPath are set")
+		host = hostPort
+	} else {
+		host = unixSocketPath
+	}
+
+	var user *url.Userinfo
+	q := make(url.Values)
+
+	if tlsAndAuth {
+		require.Empty(tb, unixSocketPath, "unixSocketPath cannot be used with TLS")
+
+		// we don't separate TLS and auth just for simplicity of our test configurations
+		q.Set("tls", "true")
+		q.Set("tlsCertificateKeyFile", filepath.Join(CertsRoot, "client.pem"))
+		q.Set("tlsCaFile", filepath.Join(CertsRoot, "rootCA-cert.pem"))
+		q.Set("authMechanism", "PLAIN")
+		user = url.UserPassword("username", "password")
+	}
+
+	// TODO https://github.com/FerretDB/FerretDB/issues/1507
+	u := &url.URL{
+		Scheme:   "mongodb",
+		Host:     host,
+		Path:     "/",
+		User:     user,
+		RawQuery: q.Encode(),
+	}
+
+	return u.String()
+}
+
 // setupListener starts in-process FerretDB server that runs until ctx is canceled.
-// It returns client and MongoDB URI of that listener.
-func setupListener(tb testing.TB, ctx context.Context, logger *zap.Logger) (*mongo.Client, string) {
+// It returns basic MongoDB URI for that listener.
+func setupListener(tb testing.TB, ctx context.Context, logger *zap.Logger) string {
 	tb.Helper()
 
 	_, span := otel.Tracer("").Start(ctx, "setupListener")
@@ -170,20 +209,12 @@ func setupListener(tb testing.TB, ctx context.Context, logger *zap.Logger) (*mon
 
 	l := clientconn.NewListener(&listenerOpts)
 
-	runCtx, runCancel := context.WithCancel(ctx)
 	runDone := make(chan struct{})
 
-	// that prevents the deadlock on failed client setup; see below
-	defer func() {
-		if tb.Failed() {
-			runCancel()
-		}
-	}()
-
 	go func() {
 		defer close(runDone)
 
-		err := l.Run(runCtx)
+		err := l.Run(ctx)
 		if err == nil || errors.Is(err, context.Canceled) {
 			logger.Info("Listener stopped without error")
 		} else {
@@ -196,24 +227,22 @@ func setupListener(tb testing.TB, ctx context.Context, logger *zap.Logger) (*mon
 		<-runDone
 	})
 
-	var opts buildInProcessFerretDBURIOpts
+	var hostPort, unixSocketPath string
+	var tlsAndAuth bool
 
 	switch {
 	case *targetTLSF:
-		opts.hostPort = l.TLSAddr().String()
-		opts.tlsAndAuth = true
+		hostPort = l.TLSAddr().String()
+		tlsAndAuth = true
 	case *targetUnixSocketF:
-		opts.unixSocketPath = l.UnixAddr().String()
+		unixSocketPath = l.UnixAddr().String()
 	default:
-		opts.hostPort = l.TCPAddr().String()
+		hostPort = l.TCPAddr().String()
 	}
 
-	// those will fail the test if in-process FerretDB is not working;
-	// for example, when backend is down
-	uri := buildInProcessFerretDBURI(tb, &opts)
-	client := setupClient(tb, ctx, uri)
+	uri := listenerMongoDBURI(tb, hostPort, unixSocketPath, tlsAndAuth)
 
 	logger.Info("Listener started", zap.String("handler", handler), zap.String("uri", uri))
 
-	return client, uri
+	return uri
 }
diff --git a/integration/setup/setup.go b/integration/setup/setup.go
index 953b3f9eef2b..b4820cc9b26e 100644
--- a/integration/setup/setup.go
+++ b/integration/setup/setup.go
@@ -136,14 +136,12 @@ func SetupWithOpts(tb testing.TB, opts *SetupOpts) *SetupResult {
 	}
 	logger := testutil.LevelLogger(tb, level)
 
-	var client *mongo.Client
 	uri := *targetURLF
-
-	if *targetURLF == "" {
-		client, uri = setupListener(tb, setupCtx, logger)
+	if uri == "" {
+		uri = setupListener(tb, setupCtx, logger)
 	}
 
-	if opts.ExtraOptions != nil || *targetURLF != "" {
+	if opts.ExtraOptions != nil {
 		u, err := url.Parse(uri)
 		require.NoError(tb, err)
 
@@ -157,13 +155,11 @@ func SetupWithOpts(tb testing.TB, opts *SetupOpts) *SetupResult {
 
 		u.RawQuery = q.Encode()
 		uri = u.String()
-
-		// If ExtraOptions is set for in-process FerretDB, two clients are created
-		// on purpose. setupListener creates a client to check in-process FerretDB
-		// options, and this client is created with extra options used for tests.
-		client = setupClient(tb, setupCtx, uri)
+		tb.Logf("URI with extra options: %s", uri)
 	}
 
+	client := setupClient(tb, setupCtx, uri)
+
 	// register cleanup function after setupListener registers its own to preserve full logs
 	tb.Cleanup(cancel)
 
diff --git a/integration/setup/setup_compat.go b/integration/setup/setup_compat.go
index f6edfaccc867..b4e4278e37d1 100644
--- a/integration/setup/setup_compat.go
+++ b/integration/setup/setup_compat.go
@@ -94,7 +94,8 @@ func SetupCompatWithOpts(tb testing.TB, opts *SetupCompatOpts) *SetupCompatResul
 
 	var targetClient *mongo.Client
 	if *targetURLF == "" {
-		targetClient, _ = setupListener(tb, setupCtx, logger)
+		uri := setupListener(tb, setupCtx, logger)
+		targetClient = setupClient(tb, setupCtx, uri)
 	} else {
 		targetClient = setupClient(tb, setupCtx, *targetURLF)
 	}

From 676af8abd7a8de28ecafd918caae2ba3aeaa9a14 Mon Sep 17 00:00:00 2001
From: Alexey Palazhchenko <alexey.palazhchenko@ferretdb.io>
Date: Wed, 28 Jun 2023 22:33:10 +0400
Subject: [PATCH 28/28] Refactor

---
 ferretdb/ferretdb.go          |  6 +++---
 integration/setup/listener.go | 12 +++++++-----
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/ferretdb/ferretdb.go b/ferretdb/ferretdb.go
index e3faee3589c4..43c4cdd70693 100644
--- a/ferretdb/ferretdb.go
+++ b/ferretdb/ferretdb.go
@@ -184,9 +184,9 @@ func (f *FerretDB) MongoDBURI() string {
 
 	switch {
 	case f.config.Listener.TLS != "":
-		q := make(url.Values)
-
-		q.Set("tls", "true")
+		q := url.Values{
+			"tls": []string{"true"},
+		}
 
 		u = &url.URL{
 			Scheme:   "mongodb",
diff --git a/integration/setup/listener.go b/integration/setup/listener.go
index 7f33f17d5cdd..28fe876b3159 100644
--- a/integration/setup/listener.go
+++ b/integration/setup/listener.go
@@ -77,16 +77,18 @@ func listenerMongoDBURI(tb testing.TB, hostPort, unixSocketPath string, tlsAndAu
 	}
 
 	var user *url.Userinfo
-	q := make(url.Values)
+	var q url.Values
 
 	if tlsAndAuth {
 		require.Empty(tb, unixSocketPath, "unixSocketPath cannot be used with TLS")
 
 		// we don't separate TLS and auth just for simplicity of our test configurations
-		q.Set("tls", "true")
-		q.Set("tlsCertificateKeyFile", filepath.Join(CertsRoot, "client.pem"))
-		q.Set("tlsCaFile", filepath.Join(CertsRoot, "rootCA-cert.pem"))
-		q.Set("authMechanism", "PLAIN")
+		q = url.Values{
+			"tls":                   []string{"true"},
+			"tlsCertificateKeyFile": []string{filepath.Join(CertsRoot, "client.pem")},
+			"tlsCaFile":             []string{filepath.Join(CertsRoot, "rootCA-cert.pem")},
+			"authMechanism":         []string{"PLAIN"},
+		}
 		user = url.UserPassword("username", "password")
 	}