test: properly handle race conditions in modal tests

Author: edusperoni

apps/nativescript-demo-ng/src/tests/modal-dialog.spec.ts

@@ -2,10 +2,30 @@
 import { Component, inject, NgModule, NO_ERRORS_SCHEMA, ViewContainerRef } from '@angular/core';
 import { TestBed, waitForAsync } from '@angular/core/testing';
 import { FrameService, ModalDialogParams, ModalDialogService, NativeScriptCommonModule, NSLocationStrategy, Outlet } from '@nativescript/angular';
-import { Frame, isIOS } from '@nativescript/core';
+import { Application, View } from '@nativescript/core';
 
 import { FakeFrameService } from './ns-location-strategy.spec';
-const CLOSE_WAIT = isIOS ? 1000 : 0;
+
+/**
+ * Resolves once `condition` is truthy, polling on each frame. Unlike a fixed delay this resolves
+ * as soon as the awaited state is reached (e.g. a modal finishing its animated dismissal), with a
+ * bounded safety timeout so a stuck condition can't hang the suite.
+ */
+function waitUntil(condition: () => boolean, timeout = 5000): Promise<void> {
+  return new Promise((resolve, reject) => {
+    const start = Date.now();
+    const check = () => {
+      if (condition()) {
+        resolve();
+      } else if (Date.now() - start > timeout) {
+        reject(new Error('Timed out waiting for condition'));
+      } else {
+        setTimeout(check, 16);
+      }
+    };
+    check();
+  });
+}
 
 @Component({
   selector: 'modal-comp',
@@ -75,17 +95,22 @@ describe('modal-dialog', () => {
   //     done()
   //   });
 
-  afterEach((done) => {
-    const page = Frame.topmost().currentPage;
-    if (page && page.modal) {
-      console.log('Warning: closing a leftover modal page!');
-      page.modal.closeModal();
-    }
-    if (CLOSE_WAIT > 0) {
-      setTimeout(done, CLOSE_WAIT);
-    } else {
-      done();
-    }
+  afterEach(async () => {
+    // Close any modal still presented (via core's global registry) and wait until it has actually
+    // finished dismissing before the next test runs.
+    //
+    // Note: `closeModal()` removes the modal from `_rootModalViews` *synchronously*, before the
+    // animated dismissal starts, so the registry being empty does NOT mean the modal is gone. On
+    // iOS the parent keeps a `presentedViewController` until the dismiss animation completes — and
+    // that's exactly what makes the next `showModal` fail with "already presenting" — so wait on it.
+    const open = ((Application.getRootView()?._getRootModalViews() ?? []) as View[]).slice();
+    // Capture parents before closing: `closeModal()` nulls `_modalParent` synchronously.
+    const parents = open
+      .map((modal) => (modal as { _modalParent?: View })._modalParent)
+      .filter((parent): parent is View => !!parent);
+    open.forEach((modal) => modal.closeModal());
+    const isPresenting = (parent: View) => !!(parent as { viewController?: { presentedViewController?: unknown } }).viewController?.presentedViewController;
+    await waitUntil(() => parents.every((parent) => !isPresenting(parent))).catch(() => undefined);
   });
 
   it('showModal does not throws when there is no viewContainer provided', waitForAsync(async () => {