[chore][processor/batchprocessor] Enable goleak check (#9224)

**Description:** <Describe what has changed.>
<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
Add `goleak` to detect leaks in tests. Leaking goroutines were detected
that were caused by a dependency that we can ignore
(`go.opencensus.io/stats/view.(*worker).start`), some `Shutdown` calls
were also added that were missing.

**Link to tracking Issue:** <Issue number if applicable>
#9165 

**Testing:** <Describe what testing was performed and which tests were
added.>
Added check is passing as well as existing tests.

processor/batchprocessor/batch_processor_test.go

@@ -1034,7 +1034,7 @@ func TestBatchProcessorMetadataCardinalityLimit(t *testing.T) {
 
 func TestBatchZeroConfig(t *testing.T) {
 	// This is a no-op configuration. No need for a timer, no
-	// minimum, no mxaimum, just a pass through.
+	// minimum, no maximum, just a pass through.
 	cfg := Config{}
 
 	require.NoError(t, cfg.Validate())
@@ -1047,6 +1047,7 @@ func TestBatchZeroConfig(t *testing.T) {
 	batcher, err := newBatchLogsProcessor(creationSet, sink, &cfg, false)
 	require.NoError(t, err)
 	require.NoError(t, batcher.Start(context.Background(), componenttest.NewNopHost()))
+	defer func() { require.NoError(t, batcher.Shutdown(context.Background())) }()
 
 	expect := 0
 	for requestNum := 0; requestNum < requestCount; requestNum++ {
@@ -1087,6 +1088,7 @@ func TestBatchSplitOnly(t *testing.T) {
 	batcher, err := newBatchLogsProcessor(creationSet, sink, &cfg, false)
 	require.NoError(t, err)
 	require.NoError(t, batcher.Start(context.Background(), componenttest.NewNopHost()))
+	defer func() { require.NoError(t, batcher.Shutdown(context.Background())) }()
 
 	for requestNum := 0; requestNum < requestCount; requestNum++ {
 		ld := testdata.GenerateLogs(logsPerRequest)

processor/batchprocessor/factory_test.go

@@ -29,12 +29,15 @@ func TestCreateProcessor(t *testing.T) {
 	tp, err := factory.CreateTracesProcessor(context.Background(), creationSet, cfg, nil)
 	assert.NotNil(t, tp)
 	assert.NoError(t, err, "cannot create trace processor")
+	assert.NoError(t, tp.Shutdown(context.Background()))
 
 	mp, err := factory.CreateMetricsProcessor(context.Background(), creationSet, cfg, nil)
 	assert.NotNil(t, mp)
 	assert.NoError(t, err, "cannot create metric processor")
+	assert.NoError(t, mp.Shutdown(context.Background()))
 
 	lp, err := factory.CreateLogsProcessor(context.Background(), creationSet, cfg, nil)
 	assert.NotNil(t, lp)
 	assert.NoError(t, err, "cannot create logs processor")
+	assert.NoError(t, lp.Shutdown(context.Background()))
 }

processor/batchprocessor/go.mod

@@ -22,6 +22,7 @@ require (
 	go.opentelemetry.io/otel/sdk v1.21.0
 	go.opentelemetry.io/otel/sdk/metric v1.21.0
 	go.opentelemetry.io/otel/trace v1.21.0
+	go.uber.org/goleak v1.3.0
 	go.uber.org/multierr v1.11.0
 	go.uber.org/zap v1.26.0
 )

processor/batchprocessor/package_test.go

@@ -0,0 +1,17 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package batchprocessor
+
+import (
+	"testing"
+
+	"go.uber.org/goleak"
+)
+
+// The IgnoreTopFunction call prevents catching the leak generated by opencensus
+// defaultWorker.Start which at this time is part of the package's init call.
+// See https://github.com/open-telemetry/opentelemetry-collector/issues/9165#issuecomment-1874836336 for more context.
+func TestMain(m *testing.M) {
+	goleak.VerifyTestMain(m, goleak.IgnoreTopFunction("go.opencensus.io/stats/view.(*worker).start"))
+}