Add tests using new test framework

api/global/internal/propagator_test.go

@@ -0,0 +1,53 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package internal_test
+
+import (
+	"context"
+	"testing"
+
+	"go.opentelemetry.io/otel/api/global/internal"
+	"go.opentelemetry.io/otel/oteltest"
+)
+
+func TestTextMapPropagatorDelegation(t *testing.T) {
+	internal.ResetForTest()
+	ctx := context.Background()
+	carrier := oteltest.NewTextMapCarrier(nil)
+
+	// The default should be a noop.
+	prior := internal.TextMapPropagator()
+	prior.Inject(ctx, carrier)
+	ctx = prior.Extract(ctx, carrier)
+	if !carrier.GotN(t, 0) || !carrier.SetN(t, 0) {
+		return
+	}
+
+	// Make sure the delegate woks as expected.
+	delegate := oteltest.NewTextMapPropagator("test")
+	delegate.Inject(ctx, carrier)
+	ctx = delegate.Extract(ctx, carrier)
+	if !delegate.InjectedN(t, carrier, 1) || !delegate.ExtractedN(t, ctx, 1) {
+		return
+	}
+
+	// The prior propagator should use the delegate after it is set as the
+	// global.
+	internal.SetTextMapPropagator(delegate)
+	prior.Inject(ctx, carrier)
+	ctx = prior.Extract(ctx, carrier)
+	delegate.InjectedN(t, carrier, 2)
+	delegate.ExtractedN(t, ctx, 2)
+}