Improve prometheus_helper coverage and collector_manager coverage

xonvanetta · Mar 21, 2023 · 4475b3b · 4475b3b
1 parent 90dbdff
commit 4475b3b
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Showing 3 changed files with 119 additions and 9 deletions.
diff --git a/collectors/collector_manager_test.go b/collectors/collector_manager_test.go
@@ -2,6 +2,8 @@ package collectors
 
 import (
 	"context"
+	"errors"
+	"sync"
 	"testing"
 
 	"github.com/prometheus/client_golang/prometheus"
@@ -16,9 +18,21 @@ func TestNewCollectorManager(t *testing.T) {
 	}
 }
 
-type mockCollector struct{}
+type mockCollector struct {
+	shouldFail bool
+}
+
+func newMockCollector(shouldFail bool) *mockCollector {
+	return &mockCollector{
+		shouldFail: shouldFail,
+	}
+}
 
 func (m *mockCollector) Collect(ctx context.Context, ch chan<- prometheus.Metric) error {
+	if m.shouldFail {
+		return errors.New("mock collector failed")
+	}
+
 	ch <- prometheus.MustNewConstMetric(
 		prometheus.NewDesc("mock_metric", "mock metric description", nil, nil),
 		prometheus.GaugeValue,
@@ -28,20 +42,72 @@ func (m *mockCollector) Collect(ctx context.Context, ch chan<- prometheus.Metric
 }
 
 func TestCollect(t *testing.T) {
+	t.Run("should fail", func(t *testing.T) {
+		cm := &CollectorManager{
+			collectors: map[string]Collector{
+				"mock": newMockCollector(true),
+			},
+			scrapeDurations: getScrapeDurationsCollector(),
+		}
+
+		ch := make(chan prometheus.Metric)
+
+		var wg sync.WaitGroup
+		wg.Add(1)
+		go func() {
+			cm.Collect(ch)
+			wg.Done()
+		}()
+
+		select {
+		case <-ch:
+			t.Error("Expected no metric to be sent to the channel")
+		case <-func() chan struct{} {
+			done := make(chan struct{})
+			go func() {
+				wg.Wait()
+				close(done)
+			}()
+			return done
+		}():
+			// No metric was sent to the channel, which is expected.
+		}
+	})
+
+	t.Run("should succeed", func(t *testing.T) {
+		cm := &CollectorManager{
+			collectors: map[string]Collector{
+				"mock": newMockCollector(false),
+			},
+			scrapeDurations: getScrapeDurationsCollector(),
+		}
+
+		ch := make(chan prometheus.Metric)
+		go cm.Collect(ch)
+
+		metric := <-ch
+
+		desc := metric.Desc()
+		expectedDesc := "Desc{fqName: \"mock_metric\", help: \"mock metric description\", constLabels: {}, variableLabels: []}"
+		if desc.String() != expectedDesc {
+			t.Errorf("Expected metric description to be '%s', got %s", expectedDesc, desc.String())
+		}
+	})
+}
+
+func TestDescribe(t *testing.T) {
 	cm := &CollectorManager{
 		collectors: map[string]Collector{
-			"mock": &mockCollector{},
+			"mock": newMockCollector(false),
 		},
 		scrapeDurations: getScrapeDurationsCollector(),
 	}
 
-	ch := make(chan prometheus.Metric)
-	go cm.Collect(ch)
-
-	metric := <-ch
+	ch := make(chan *prometheus.Desc, 1)
+	cm.Describe(ch)
 
-	desc := metric.Desc()
-	expectedDesc := "Desc{fqName: \"mock_metric\", help: \"mock metric description\", constLabels: {}, variableLabels: []}"
+	desc := <-ch
+	expectedDesc := "Desc{fqName: \"logstash_exporter_scrape_duration_seconds\", help: \"logstash_exporter: Duration of a scrape job.\", constLabels: {}, variableLabels: [collector result]}"
 	if desc.String() != expectedDesc {
 		t.Errorf("Expected metric description to be '%s', got %s", expectedDesc, desc.String())
 	}

diff --git a/prometheus_helper/prometheus_helper.go b/prometheus_helper/prometheus_helper.go
@@ -49,7 +49,7 @@ type CustomCollector struct {
 
 // Describe implements the prometheus.Collector interface.
 func (c *CustomCollector) Describe(ch chan<- *prometheus.Desc) {
-	c.metric.Desc()
+	ch <- c.metric.Desc()
 }
 
 // Collect implements the prometheus.Collector interface.

diff --git a/prometheus_helper/prometheus_helper_test.go b/prometheus_helper/prometheus_helper_test.go
@@ -64,3 +64,47 @@ func TestExtractFqdnName(t *testing.T) {
 		}
 	})
 }
+
+func TestExtractValueFromMetric(t *testing.T) {
+	t.Run("should extract value from a metric", func(t *testing.T) {
+		metricDesc := prometheus.NewDesc("test_metric", "test metric help", nil, nil)
+		metricValue := 42.0
+		metric := prometheus.MustNewConstMetric(metricDesc, prometheus.GaugeValue, metricValue)
+
+		extractedValue, err := ExtractValueFromMetric(metric)
+		if err != nil {
+			t.Errorf("Unexpected error: %v", err)
+		}
+
+		if extractedValue != metricValue {
+			t.Errorf("Expected extracted value to be %f, got %f", metricValue, extractedValue)
+		}
+	})
+
+	t.Run("should return an error when unable to write metric", func(t *testing.T) {
+		metricDesc := prometheus.NewDesc("test_metric", "test metric help", nil, nil)
+		exampleErr := fmt.Errorf("example error")
+		invalidMetric := prometheus.NewInvalidMetric(metricDesc, exampleErr)
+
+		customCollector := &CustomCollector{
+			metric: invalidMetric,
+		}
+
+		registry := prometheus.NewRegistry()
+		err := registry.Register(customCollector)
+
+		if err != nil {
+			t.Errorf("Unexpected error: %v", err)
+		}
+
+		extractedValue, err := ExtractValueFromMetric(invalidMetric)
+
+		if err == nil {
+			t.Errorf("Expected error but got nil")
+		}
+
+		if extractedValue != 0 {
+			t.Errorf("Expected extracted value to be 0, got %f", extractedValue)
+		}
+	})
+}