feat(trace): add trace test helpers (#3108)

core/trace/tracetest/tracetest.go

@@ -0,0 +1,20 @@
+package tracetest
+
+import (
+	"testing"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/sdk/trace"
+	"go.opentelemetry.io/otel/sdk/trace/tracetest"
+)
+
+// NewInMemoryExporter returns a new InMemoryExporter
+// and sets it as the global for tests.
+func NewInMemoryExporter(t *testing.T) *tracetest.InMemoryExporter {
+	me := tracetest.NewInMemoryExporter()
+	t.Cleanup(func() {
+		me.Reset()
+	})
+	otel.SetTracerProvider(trace.NewTracerProvider(trace.WithSyncer(me)))
+	return me
+}