FerretDB · AlekSi · Dec 20, 2023 · Dec 12, 2023 · Dec 12, 2023 · Dec 14, 2023
@@ -46,7 +46,7 @@ func TestCreateUser(t *testing.T) {
 	} else {
 		// Erase any previously saved user in the database.
 		_, err := users.DeleteMany(ctx, bson.D{{"db", db.Name()}})
-		assert.NoError(t, err)
+		require.NoError(t, err)
 	}
 
 	testCases := map[string]struct { //nolint:vet // for readability
@@ -97,9 +97,7 @@ func TestCreateUser(t *testing.T) {
 				{"pwd", "password"},
 			},
 			expected: bson.D{
-				{
-					"ok", float64(1),
-				},
+				{"ok", float64(1)},
 			},
 		},
 		"WithComment": {
@@ -110,9 +108,7 @@ func TestCreateUser(t *testing.T) {
 				{"comment", "test string comment"},
 			},
 			expected: bson.D{
-				{
-					"ok", float64(1),
-				},
+				{"ok", float64(1)},
 			},
 		},
 		"MissingRoles": {
@@ -128,12 +124,14 @@ func TestCreateUser(t *testing.T) {
 		},
 	}
 
+	// The subtest "AlreadyExists" tries to create the following user, which should fail with an error that the user already exists.
+	// Here, we create the user for the very first time to populate the database.
 	err := db.RunCommand(ctx, bson.D{
 		{"createUser", "should_already_exist"},
 		{"roles", bson.A{}},
 		{"pwd", "password"},
 	}).Err()
-	assert.NoError(t, err)
+	require.NoError(t, err)
 
 	for name, tc := range testCases {
 		name, tc := name, tc

@@ -0,0 +1,115 @@
+// Copyright 2021 FerretDB Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package users
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/mongo"
+
+	"github.com/FerretDB/FerretDB/integration"
+	"github.com/FerretDB/FerretDB/integration/setup"
+	"github.com/FerretDB/FerretDB/internal/util/must"
+	"github.com/FerretDB/FerretDB/internal/util/testutil"
+)
+
+func TestDropUser(t *testing.T) {
+	t.Parallel()
+
+	ctx, collection := setup.Setup(t)
+	db := collection.Database()
+	client := db.Client()
+	users := client.Database("admin").Collection("system.users")
+
+	// TODO https://github.com/FerretDB/FerretDB/issues/1492
+	if setup.IsMongoDB(t) {
+		require.NoError(t, collection.Database().RunCommand(ctx, bson.D{
+			{"dropAllUsersFromDatabase", 1},
+		}).Err())
+	} else {
+		// Erase any previously saved user in the database.
+		_, err := users.DeleteMany(ctx, bson.D{{"db", db.Name()}})
+		require.NoError(t, err)
+	}
+
+	err := db.RunCommand(ctx, bson.D{
+		{"createUser", "a_user"},
+		{"roles", bson.A{}},
+		{"pwd", "password"},
+	}).Err()
+	require.NoError(t, err)
+
+	testCases := map[string]struct { //nolint:vet // for readability
+		payload    bson.D
+		err        *mongo.CommandError
+		altMessage string
+		expected   bson.D
+	}{
+		"NotFound": {
+			payload: bson.D{
+				{"dropUser", "not_found_user"},
+			},
+			err: &mongo.CommandError{
+				Code:    11,
+				Name:    "UserNotFound",
+				Message: "User 'not_found_user@TestDropUser' not found",
+			},
+		},
+		"Success": {
+			payload: bson.D{
+				{"dropUser", "a_user"},
+			},
+			expected: bson.D{
+				{"ok", float64(1)},
+			},
+		},
+	}
+
+	for name, tc := range testCases {
+		name, tc := name, tc
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			var res bson.D
+			err := db.RunCommand(ctx, tc.payload).Decode(&res)
+			if tc.err != nil {
+				integration.AssertEqualAltCommandError(t, *tc.err, tc.altMessage, err)
+				return
+			}
+
+			require.NoError(t, err)
+
+			actual := integration.ConvertDocument(t, res)
+			actual.Remove("$clusterTime")
+			actual.Remove("operationTime")
+
+			expected := integration.ConvertDocument(t, tc.expected)
+			testutil.AssertEqual(t, expected, actual)
+
+			payload := integration.ConvertDocument(t, tc.payload)
+			assertUserNotFound(ctx, t, users, db.Name(), must.NotFail(payload.Get("dropUser")).(string))
+		})
+	}
+}
+
+// assertUserNotFound checks it the user doesn't exist in the admin.system.users collection.
+func assertUserNotFound(ctx context.Context, t testing.TB, users *mongo.Collection, dbName, username string) {
+	t.Helper()
+	err := users.FindOne(ctx, bson.D{{"user", username}, {"db", dbName}}).Err()
+	require.Equal(t, mongo.ErrNoDocuments, err, `should return "no documents" error`)
+}
@@ -39,6 +39,9 @@ const (
 	// ErrFailedToParse indicates user input parsing failure.
 	ErrFailedToParse = ErrorCode(9) // FailedToParse
 
+	// ErrUserNotFound indicates an user was not found for the accessed database.
+	ErrUserNotFound = ErrorCode(11) // UserNotFound
+
 	// ErrUnauthorized indicates that cursor is not authorized to access another namespace.
 	ErrUnauthorized = ErrorCode(13) // Unauthorized