Fix metric descriptor convertion. (#108)

Fixes #103.

Author: songy23

equivalence_test.go

@@ -39,8 +39,6 @@ import (
 )
 
 func TestStatsAndMetricsEquivalence(t *testing.T) {
-	t.Skip("Metric schema has changed. Fix this test later.")
-
 	ma, addr, stop := createMockAgent(t)
 	defer stop()
 
@@ -129,8 +127,6 @@ func TestStatsAndMetricsEquivalence(t *testing.T) {
 // This test ensures that the final responses sent by direct stats(view.Data) exporting
 // are exactly equal to those from view.Data-->OpenCensus-Proto.Metrics exporting.
 func TestEquivalenceStatsVsMetricsUploads(t *testing.T) {
-	t.Skip("Metric schema has changed. Fix this test later.")
-
 	ma, addr, doneFn := createMockAgent(t)
 	defer doneFn()
 

metrics_proto.go

@@ -42,6 +42,7 @@ import (
 )
 
 var errNilMetric = errors.New("expecting a non-nil metric")
+var errNilMetricDescriptor = errors.New("expecting a non-nil metric descriptor")
 
 type metricProtoPayload struct {
 	node     *commonpb.Node
@@ -189,7 +190,10 @@ func (se *statsExporter) protoMetricToTimeSeries(ctx context.Context, node *comm
 		resource = metric.Resource
 	}
 
-	metricName, _, _, _ := metricProseFromProto(metric)
+	metricName, _, _, err := metricProseFromProto(metric)
+	if err != nil {
+		return nil, err
+	}
 	metricType, _ := se.metricTypeFromProto(metricName)
 	metricLabelKeys := metric.GetMetricDescriptor().GetLabelKeys()
 	metricKind, _ := protoMetricDescriptorTypeToMetricKind(metric)
@@ -322,7 +326,10 @@ func (se *statsExporter) protoToMonitoringMetricDescriptor(metric *metricspb.Met
 		return nil, errNilMetric
 	}
 
-	metricName, description, unit, _ := metricProseFromProto(metric)
+	metricName, description, unit, err := metricProseFromProto(metric)
+	if err != nil {
+		return nil, err
+	}
 	metricType, _ := se.metricTypeFromProto(metricName)
 	displayName := se.displayName(metricName)
 	metricKind, valueType := protoMetricDescriptorTypeToMetricKind(metric)
@@ -364,26 +371,23 @@ func labelDescriptorsFromProto(defaults map[string]labelValue, protoLabelKeys []
 	return labelDescriptors
 }
 
-func metricProseFromProto(metric *metricspb.Metric) (name, description, unit string, ok bool) {
-	mname := metric.GetMetricDescriptor().GetName()
-	if mname != "" {
-		name = mname
-		return
-	}
-
+func metricProseFromProto(metric *metricspb.Metric) (name, description, unit string, err error) {
 	md := metric.GetMetricDescriptor()
+	if md == nil {
+		return "", "", "", errNilMetricDescriptor
+	}
 
 	name = md.GetName()
 	unit = md.GetUnit()
 	description = md.GetDescription()
 
-	if md != nil && md.Type == metricspb.MetricDescriptor_CUMULATIVE_INT64 {
+	if md.Type == metricspb.MetricDescriptor_CUMULATIVE_INT64 {
 		// If the aggregation type is count, which counts the number of recorded measurements, the unit must be "1",
 		// because this view does not apply to the recorded values.
 		unit = stats.UnitDimensionless
 	}
 
-	return
+	return name, description, unit, nil
 }
 
 func (se *statsExporter) metricTypeFromProto(name string) (string, bool) {

metrics_proto_test.go

@@ -208,8 +208,6 @@ func TestProtoMetricToCreateTimeSeriesRequest(t *testing.T) {
 }
 
 func TestProtoToMonitoringMetricDescriptor(t *testing.T) {
-	t.Skip("Metric schema has changed. Fix this test later.")
-
 	tests := []struct {
 		in      *metricspb.Metric
 		want    *googlemetricpb.MetricDescriptor
@@ -219,15 +217,8 @@ func TestProtoToMonitoringMetricDescriptor(t *testing.T) {
 	}{
 		{in: nil, wantErr: "non-nil metric"},
 		{
-			in: &metricspb.Metric{},
-			statsExporter: &statsExporter{
-				o: Options{ProjectID: "test"},
-			},
-			want: &googlemetricpb.MetricDescriptor{
-				Name:        "projects/test/metricDescriptors/custom.googleapis.com/opencensus",
-				Type:        "custom.googleapis.com/opencensus",
-				DisplayName: "OpenCensus",
-			},
+			in:      &metricspb.Metric{},
+			wantErr: "non-nil metric descriptor",
 		},
 		{
 			in: &metricspb.Metric{