do not record for empty metric config

metrics/client_test.go

@@ -58,7 +58,7 @@ func TestClientMetrics(t *testing.T) {
 	metrics.Register(cp.NewLatencyMetric(), cp.NewResultMetric())
 
 	// Reset the metrics configuration to avoid leaked state from other tests.
-	setCurMetricsConfig(nil)
+	setCurMetricsConfig(testMc)
 
 	views := cp.DefaultViews()
 	if got, want := len(views), 2; got != want {

metrics/config.go

@@ -153,7 +153,10 @@ func NewStackdriverClientConfigFromMap(config map[string]string) *StackdriverCli
 // record applies the `ros` Options to each measurement in `mss` and then records the resulting
 // measurements in the metricsConfig's designated backend.
 func (mc *metricsConfig) record(ctx context.Context, mss []stats.Measurement, ros ...stats.Options) error {
-	if mc == nil || mc.recorder == nil {
+	if mc == nil {
+		return nil
+	}
+	if mc.recorder == nil {
 		return stats.RecordWithOptions(ctx, append(ros, stats.WithMeasurements(mss...))...)
 	}
 	return mc.recorder(ctx, mss, ros...)

metrics/config_test.go

@@ -49,6 +49,13 @@ const (
 )
 
 var (
+	// A metric config used for unit tests only.
+	testMc = &metricsConfig{
+		backendDestination: Prometheus,
+		component:          "test",
+		domain:             "test",
+	}
+
 	errorTests = []struct {
 		name        string
 		ops         ExporterOptions

metrics/memstats_test.go

@@ -36,7 +36,7 @@ func TestMemStatsMetrics(t *testing.T) {
 	msp.Start(ctx, period)
 
 	// Reset the metrics configuration to avoid leaked state from other tests.
-	setCurMetricsConfig(nil)
+	setCurMetricsConfig(testMc)
 
 	views := msp.DefaultViews()
 	if got, want := len(views), 27; got != want {

metrics/record_test.go

@@ -58,9 +58,6 @@ func TestRecordServing(t *testing.T) {
 			stackdriverMetricTypePrefix: "knative.dev/unsupported",
 		},
 		measurement: measure.M(3),
-	}, {
-		name:        "empty metricsConfig",
-		measurement: measure.M(4),
 	}}
 	testRecord(t, measure, shouldReportCases)
 }
@@ -87,9 +84,6 @@ func TestRecordEventing(t *testing.T) {
 			stackdriverMetricTypePrefix: "knative.dev/unsupported",
 		},
 		measurement: measure.M(3),
-	}, {
-		name:        "empty metricsConfig",
-		measurement: measure.M(4),
 	}}
 	testRecord(t, measure, shouldReportCases)
 }
@@ -149,6 +143,9 @@ func testRecord(t *testing.T, measure *stats.Int64Measure, shouldReportCases []c
 			},
 		},
 		measurement: measure.M(5),
+	}, {
+		name:        "empty metricsConfig",
+		measurement: measure.M(4),
 	}}
 
 	for _, test := range shouldNotReportCases {

metrics/workqueue_test.go

@@ -48,7 +48,7 @@ func TestWorkqueueMetrics(t *testing.T) {
 	workqueue.SetProvider(wp)
 
 	// Reset the metrics configuration to avoid leaked state from other tests.
-	setCurMetricsConfig(nil)
+	setCurMetricsConfig(testMc)
 
 	views := wp.DefaultViews()
 	if got, want := len(views), 7; got != want {