Look for the cancelled-screenshots toast as it shows

test/page_screenshots_test.dart

@@ -712,14 +712,24 @@ void main() {
     await tester.pump();
     // It stays up, saying so, until the capture has stopped.
     expect(find.text('Stopping…'), findsOneWidget);
-    // The clock moves too, so the dialog's closing animation plays out.
+    // The clock moves too, so the dialog's closing animation plays out. The
+    // toast is shown while real time passes here, so its closing timer runs
+    // on real time: it is looked for as it shows, and taken away at once,
+    // so it neither closes before the check on a slow machine nor closes
+    // itself after the test, on a torn-down tree.
+    var toldCancelled = false;
     for (var i = 0;
         i < 400 && find.text('Saving screenshots').evaluate().isNotEmpty;
         i++) {
       await tester.runAsync(
         () => Future<void>.delayed(const Duration(milliseconds: 16)),
       );
       await tester.pump(const Duration(milliseconds: 16));
+      if (!toldCancelled &&
+          find.text('Screenshots cancelled.').evaluate().isNotEmpty) {
+        toldCancelled = true;
+        toastification.dismissAll(delayForAnimation: false);
+      }
     }
     for (var i = 0; i < 10; i++) {
       await tester.pump(const Duration(milliseconds: 100));
@@ -729,10 +739,10 @@ void main() {
     expect(find.byType(EditorToolbar), findsOneWidget);
     expect(find.text('Library'), findsNothing);
     expect(folder.listSync(), isEmpty);
-    expect(find.text('Screenshots cancelled.'), findsOneWidget);
+    expect(toldCancelled, isTrue);
     ignoreTestFontOverflow(tester);
-    // Let the toast leave.
-    await tester.pump(const Duration(seconds: 10));
+    // Let the toast's removal play out.
+    await tester.pump(const Duration(seconds: 4));
   });
 
   testWidgets('a finished capture closes only its own dialog', (tester) async {