Fix deadlocked test

After the shutdown changes in previous commits, a receiver can only shut
down after its emitter was shut down first.

.chloggen/fix_shutdown.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: pkg/stanza
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Synchronize shutdown in stanza adapter
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [31074]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: Stanza-based receivers should now flush all data before shutting down
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

pkg/stanza/adapter/converter.go

@@ -60,7 +60,7 @@ type Converter struct {
 
 	stopOnce sync.Once
 
-	// converterChan is an internal communication channel signalling stop was called
+	// converterChan is an internal communication channel signaling stop was called
 	// prevents sending to closed channels
 	converterChan chan struct{}
 

pkg/stanza/adapter/integration_test.go

@@ -151,7 +151,10 @@ func TestEmitterToConsumer(t *testing.T) {
 
 	err = logsReceiver.Start(context.Background(), componenttest.NewNopHost())
 	require.NoError(t, err)
-	defer func() { require.NoError(t, logsReceiver.Shutdown(context.Background())) }()
+	defer func() {
+		require.NoError(t, logsReceiver.emitter.Stop())
+		require.NoError(t, logsReceiver.Shutdown(context.Background()))
+	}()
 
 	go func() {
 		ctx := context.Background()