log/logtest: improve Transform usage in the example (#6938)

log/logtest/example_test.go

@@ -20,20 +20,18 @@ func Example() {
 
 	// Emit a log record (code under test).
 	l := rec.Logger("Example")
-	ctx := context.Background()
 	r := log.Record{}
 	r.SetTimestamp(time.Now())
 	r.SetSeverity(log.SeverityInfo)
 	r.SetBody(log.StringValue("Hello there"))
 	r.AddAttributes(log.String("foo", "bar"))
 	r.AddAttributes(log.Int("n", 1))
-	l.Emit(ctx, r)
+	l.Emit(context.Background(), r)
 
 	// Verify that the expected and actual log records match.
 	want := logtest.Recording{
 		logtest.Scope{Name: "Example"}: []logtest.Record{
 			{
-				Context:  context.Background(),
 				Severity: log.SeverityInfo,
 				Body:     log.StringValue("Hello there"),
 				Attributes: []log.KeyValue{
@@ -45,9 +43,11 @@ func Example() {
 	}
 	got := rec.Result()
 	logtest.AssertEqual(t, want, got,
-		// Ignore Timestamps.
-		logtest.Transform(func(time.Time) time.Time {
-			return time.Time{}
+		logtest.Transform(func(r logtest.Record) logtest.Record {
+			r = r.Clone()
+			r.Context = nil           // Ignore context.
+			r.Timestamp = time.Time{} // Ignore timestamp.
+			return r
 		}),
 	)
 	// Output: