1 files changed, 75 insertions, 0 deletions
diff --git a/event/otel/metric_test.go b/event/otel/metric_test.go
new file mode 100644
index 0000000..300f4a7
--- /dev/null
+++ b/event/otel/metric_test.go
@@ -0,0 +1,75 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package otel_test
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/google/go-cmp/cmp"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/metric/metrictest"
+	"go.opentelemetry.io/otel/metric/number"
+	"golang.org/x/exp/event"
+	"golang.org/x/exp/event/otel"
+)
+
+func TestMeter(t *testing.T) {
+	ctx := context.Background()
+	mp := metrictest.NewMeterProvider()
+	mh := otel.NewMetricHandler(mp.Meter("test"))
+	ctx = event.WithExporter(ctx, event.NewExporter(mh, nil))
+	recordMetrics(ctx)
+
+	lib := metrictest.Library{InstrumentationName: "test"}
+	emptyLabels := map[attribute.Key]attribute.Value{}
+	got := metrictest.AsStructs(mp.MeasurementBatches)
+	want := []metrictest.Measured{
+		{
+			Name:    "golang.org/x/exp/event/otel_test/hits",
+			Number:  number.NewInt64Number(8),
+			Labels:  emptyLabels,
+			Library: lib,
+		},
+		{
+			Name:    "golang.org/x/exp/event/otel_test/temp",
+			Number:  number.NewFloat64Number(-100),
+			Labels:  map[attribute.Key]attribute.Value{"location": attribute.StringValue("Mare Imbrium")},
+			Library: lib,
+		},
+		{
+			Name:    "golang.org/x/exp/event/otel_test/latency",
+			Number:  number.NewInt64Number(int64(1248 * time.Millisecond)),
+			Labels:  emptyLabels,
+			Library: lib,
+		},
+		{
+			Name:    "golang.org/x/exp/event/otel_test/latency",
+			Number:  number.NewInt64Number(int64(1255 * time.Millisecond)),
+			Labels:  emptyLabels,
+			Library: lib,
+		},
+	}
+
+	if diff := cmp.Diff(want, got, cmp.Comparer(valuesEqual)); diff != "" {
+		t.Errorf("mismatch (-want, got):\n%s", diff)
+	}
+}
+
+func valuesEqual(v1, v2 attribute.Value) bool {
+	return v1.AsInterface() == v2.AsInterface()
+}
+
+func recordMetrics(ctx context.Context) {
+	c := event.NewCounter("hits", &event.MetricOptions{Description: "Earth meteorite hits"})
+	g := event.NewFloatGauge("temp", &event.MetricOptions{Description: "moon surface temperature in Kelvin"})
+	d := event.NewDuration("latency", &event.MetricOptions{Description: "Earth-moon comms lag, milliseconds"})
+
+	c.Record(ctx, 8)
+	g.Record(ctx, -100, event.String("location", "Mare Imbrium"))
+	d.Record(ctx, 1248*time.Millisecond)
+	d.Record(ctx, 1255*time.Millisecond)
+}