package prometheus import ( "reflect" "testing" "time" dto "github.com/prometheus/client_golang/Godeps/_workspace/src/github.com/prometheus/client_model/go" ) func TestGoCollector(t *testing.T) { var ( c = NewGoCollector() ch = make(chan Metric) waitc = make(chan struct{}) closec = make(chan struct{}) old = -1 ) defer close(closec) go func() { c.Collect(ch) go func(c <-chan struct{}) { <-c }(closec) <-waitc c.Collect(ch) }() for { select { case metric := <-ch: switch m := metric.(type) { // Attention, this also catches Counter... case Gauge: pb := &dto.Metric{} m.Write(pb) if old == -1 { old = int(pb.GetGauge().GetValue()) close(waitc) continue } if diff := int(pb.GetGauge().GetValue()) - old; diff != 1 { // TODO: This is flaky in highly concurrent situations. t.Errorf("want 1 new goroutine, got %d", diff) } return default: t.Errorf("want type Gauge, got %s", reflect.TypeOf(metric)) } case <-time.After(1 * time.Second): t.Fatalf("expected collect timed out") } } }