diff --git a/prometheus/testutil/testutil.go b/prometheus/testutil/testutil.go index c47373c0b..9af60ce1d 100644 --- a/prometheus/testutil/testutil.go +++ b/prometheus/testutil/testutil.go @@ -112,31 +112,43 @@ func ToFloat64(c prometheus.Collector) float64 { panic(fmt.Errorf("collected a non-gauge/counter/untyped metric: %s", pb)) } -// CollectAndCount collects all Metrics from the provided Collector and returns their number. -// -// This can be used to assert the number of metrics collected by a given collector after certain operations. -// -// This function is only for testing purposes, and even for testing, other approaches -// are often more appropriate (see this package's documentation). -func CollectAndCount(c prometheus.Collector) int { - var ( - mCount int - mChan = make(chan prometheus.Metric) - done = make(chan struct{}) - ) - - go func() { - for range mChan { - mCount++ - } - close(done) - }() +// CollectAndCount registers the provided Collector with a newly created +// pedantic Registry. It then calls GatherAndCount with that Registry and with +// the provided metricNames. In the unlikely case that the registration or the +// gathering fails, this function panics. (This is inconsistent with the other +// CollectAnd… functions in this package and has historical reasons. Changing +// the function signature would be a breaking change and will therefore only +// happen with the next major version bump.) +func CollectAndCount(c prometheus.Collector, metricNames ...string) int { + reg := prometheus.NewPedanticRegistry() + if err := reg.Register(c); err != nil { + panic(fmt.Errorf("registering collector failed: %s", err)) + } + result, err := GatherAndCount(reg, metricNames...) + if err != nil { + panic(err) + } + return result +} - c.Collect(mChan) - close(mChan) - <-done +// GatherAndCount gathers all metrics from the provided Gatherer and counts +// them. It returns the number of metric children in all gathered metric +// families together. If any metricNames are provided, only metrics with those +// names are counted. +func GatherAndCount(g prometheus.Gatherer, metricNames ...string) (int, error) { + got, err := g.Gather() + if err != nil { + return 0, fmt.Errorf("gathering metrics failed: %s", err) + } + if metricNames != nil { + got = filterMetrics(got, metricNames) + } - return mCount + result := 0 + for _, mf := range got { + result += len(mf.GetMetric()) + } + return result, nil } // CollectAndCompare registers the provided Collector with a newly created diff --git a/prometheus/testutil/testutil_test.go b/prometheus/testutil/testutil_test.go index aaf670786..56d993382 100644 --- a/prometheus/testutil/testutil_test.go +++ b/prometheus/testutil/testutil_test.go @@ -306,3 +306,30 @@ some_total{label1="value1"} 1 t.Errorf("Expected\n%#+v\nGot:\n%#+v", expectedError, err.Error()) } } + +func TestCollectAndCount(t *testing.T) { + c := prometheus.NewCounterVec( + prometheus.CounterOpts{ + Name: "some_total", + Help: "A value that represents a counter.", + }, + []string{"foo"}, + ) + if got, want := CollectAndCount(c), 0; got != want { + t.Errorf("unexpected metric count, got %d, want %d", got, want) + } + c.WithLabelValues("bar") + if got, want := CollectAndCount(c), 1; got != want { + t.Errorf("unexpected metric count, got %d, want %d", got, want) + } + c.WithLabelValues("baz") + if got, want := CollectAndCount(c), 2; got != want { + t.Errorf("unexpected metric count, got %d, want %d", got, want) + } + if got, want := CollectAndCount(c, "some_total"), 2; got != want { + t.Errorf("unexpected metric count, got %d, want %d", got, want) + } + if got, want := CollectAndCount(c, "some_other_total"), 0; got != want { + t.Errorf("unexpected metric count, got %d, want %d", got, want) + } +}