Release retired document sources outside the cache lock

internal/atspi/browser_native_test.go

@@ -390,6 +390,7 @@ waitReload:
 					if !activated {
 						t.Fatal("captured link action did not update the page")
 					}
+					testNativeBrowserDocumentEviction(t, adapter)
 					testNativeBrowserBackgroundLoad(t, adapter)
 					return
 				}
@@ -481,3 +482,34 @@ func testNativeBrowserBackgroundLoad(t *testing.T, adapter *Adapter) {
 		}
 	}
 }
+
+// More loads than the retained-slot limit force disposal of old native objects.
+// libatspi can synchronously deliver defunct callbacks during that disposal.
+func testNativeBrowserDocumentEviction(t *testing.T, adapter *Adapter) {
+	t.Helper()
+	for index := 0; index < maxStashedDocuments+2; index++ {
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		if out, err := exec.CommandContext(ctx, "xdotool", "key", "--clearmodifiers", "ctrl+r").CombinedOutput(); err != nil {
+			cancel()
+			t.Fatalf("reload %d: %v %s", index, err, out)
+		}
+		var loaded ObjectID
+		for !loaded.Valid() {
+			select {
+			case event := <-adapter.Events():
+				if event.Type == DocumentLoadCompleteEvent && event.Source.Name == "Cthulhu Browser Probe" {
+					loaded = event.Source.ID()
+				}
+			case <-ctx.Done():
+				cancel()
+				t.Fatalf("reload %d: load completion missing", index)
+			}
+		}
+		tree, err := adapter.CaptureDocument(ctx, loaded)
+		cancel()
+		if err != nil {
+			t.Fatalf("capture after reload %d: %v", index, err)
+		}
+		findNamedReference(t, tree, "Browser foundation")
+	}
+}