Add a SpanRecorder to the sdk/trace/tracetest (#2132)

* Add a SpanRecorder to the sdk/trace/tracetest

* Add changes to changelog

* Run make precommit

* Rename tests

CHANGELOG.md

@@ -34,6 +34,8 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Added a new `Link` type under the SDK `otel/sdk/trace` package that counts the number of attributes that were dropped for surpassing the `AttributePerLinkCountLimit` configured in the Span's `SpanLimits`.
   This new type replaces the equal-named API `Link` type found in the `otel/trace` package for most usages within the SDK.
   For example, instances of this type are now returned by the `Links()` function of `ReadOnlySpan`s provided in places like the `OnEnd` function of `SpanProcessor` implementations. (#2118)
+- Added the `SpanRecorder` type to the `go.opentelemetry.io/otel/skd/trace/tracetest` package.
+  This type can be used with the default SDK as a `SpanProcessor` during testing. (#2132)
 
 ### Changed
 

sdk/trace/tracetest/recorder.go

@@ -0,0 +1,67 @@
+// 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 tracetest // import "go.opentelemetry.io/otel/sdk/trace/tracetest"
+
+import (
+	"context"
+
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+)
+
+// SpanRecorder records started and ended spans.
+type SpanRecorder struct {
+	started []sdktrace.ReadWriteSpan
+	ended   []sdktrace.ReadOnlySpan
+}
+
+var _ sdktrace.SpanProcessor = (*SpanRecorder)(nil)
+
+func NewSpanRecorder() *SpanRecorder {
+	return new(SpanRecorder)
+}
+
+// OnStart records started spans.
+func (sr *SpanRecorder) OnStart(_ context.Context, s sdktrace.ReadWriteSpan) {
+	sr.started = append(sr.started, s)
+}
+
+// OnEnd records completed spans.
+func (sr *SpanRecorder) OnEnd(s sdktrace.ReadOnlySpan) {
+	sr.ended = append(sr.ended, s)
+}
+
+// Shutdown does nothing.
+func (sr *SpanRecorder) Shutdown(context.Context) error {
+	return nil
+}
+
+// ForceFlush does nothing.
+func (sr *SpanRecorder) ForceFlush(context.Context) error {
+	return nil
+}
+
+// Started returns a copy of all started spans that have been recorded.
+func (sr *SpanRecorder) Started() []sdktrace.ReadWriteSpan {
+	dst := make([]sdktrace.ReadWriteSpan, len(sr.started))
+	copy(dst, sr.started)
+	return dst
+}
+
+// Ended returns a copy of all ended spans that have been recorded.
+func (sr *SpanRecorder) Ended() []sdktrace.ReadOnlySpan {
+	dst := make([]sdktrace.ReadOnlySpan, len(sr.ended))
+	copy(dst, sr.ended)
+	return dst
+}

sdk/trace/tracetest/recorder_test.go

@@ -0,0 +1,85 @@
+// 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 tracetest
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+)
+
+type rwSpan struct {
+	sdktrace.ReadWriteSpan
+}
+
+func TestSpanRecorderOnStartAppends(t *testing.T) {
+	s0, s1 := new(rwSpan), new(rwSpan)
+	ctx := context.Background()
+	sr := new(SpanRecorder)
+
+	assert.Len(t, sr.started, 0)
+	sr.OnStart(ctx, s0)
+	assert.Len(t, sr.started, 1)
+	sr.OnStart(ctx, s1)
+	assert.Len(t, sr.started, 2)
+
+	// Ensure order correct.
+	started := sr.Started()
+	assert.Same(t, s0, started[0])
+	assert.Same(t, s1, started[1])
+}
+
+type roSpan struct {
+	sdktrace.ReadOnlySpan
+}
+
+func TestSpanRecorderOnEndAppends(t *testing.T) {
+	s0, s1 := new(roSpan), new(roSpan)
+	sr := new(SpanRecorder)
+
+	assert.Len(t, sr.ended, 0)
+	sr.OnEnd(s0)
+	assert.Len(t, sr.ended, 1)
+	sr.OnEnd(s1)
+	assert.Len(t, sr.ended, 2)
+
+	// Ensure order correct.
+	ended := sr.Ended()
+	assert.Same(t, s0, ended[0])
+	assert.Same(t, s1, ended[1])
+}
+
+func TestSpanRecorderShutdownNoError(t *testing.T) {
+	ctx := context.Background()
+	assert.NoError(t, new(SpanRecorder).Shutdown(ctx))
+
+	var c context.CancelFunc
+	ctx, c = context.WithCancel(ctx)
+	c()
+	assert.NoError(t, new(SpanRecorder).Shutdown(ctx))
+}
+
+func TestSpanRecorderForceFlushNoError(t *testing.T) {
+	ctx := context.Background()
+	assert.NoError(t, new(SpanRecorder).ForceFlush(ctx))
+
+	var c context.CancelFunc
+	ctx, c = context.WithCancel(ctx)
+	c()
+	assert.NoError(t, new(SpanRecorder).ForceFlush(ctx))
+}