Patrol E2e Testing

---
name: patrol-e2e-testing
description: "Use when writing E2E/integration tests, testing native interactions like permissions or system dialogs, capturing UI regressions, or validating cross-platform behavior (Patrol 4.x)."
license: MIT
---

# Patrol E2E Testing Skill

Design, implement, and run end-to-end (E2E) tests using Patrol 4.x in Flutter projects.

## When to Use

Use this skill when:

* A new screen or user flow needs E2E test coverage.
* A feature interacts with native components (permissions, notifications, system dialogs, deep links).
* A UI bug should be captured as a regression test.
* Cross-platform behavior (Android / iOS / Web) must be validated.
* Setting up Patrol in a new or existing Flutter project.

## Setup

Follow the official Patrol documentation for installation and project initialization:
[https://patrol.leancode.co/documentation#setup](https://patrol.leancode.co/documentation#setup)

Key Patrol conventions:

* Add `patrol` as a dev dependency.
* Place tests in `patrol_test/`.
* Name test files with a `_test.dart` suffix.
* Execute tests with `patrol test`.

## Workflow

Follow these steps when implementing or updating Patrol tests.

### 1. Identify the user journey

Break the feature into:

* **Actions**: taps, scrolls, input, navigation, deep links.
* **Observable outcomes**: visible text, screen changes, enabled buttons, dialogs.

Rules:

* One test per primary (happy-path) journey.
* Separate tests for critical edge cases.
* Avoid combining unrelated flows in a single test.

### 2. Structure the Patrol test

Basic Patrol structure:

```dart
import 'package:flutter_test/flutter_test.dart';
import 'package:patrol/patrol.dart';

void main() {
  patrolTest(
    'user can log in successfully',
    ($) async {
      await $.pumpWidgetAndSettle(const MyApp());

      const email = String.fromEnvironment('E2E_EMAIL');
      const password = String.fromEnvironment('E2E_PASSWORD');

      await $(#emailField).enterText(email);
      await $(#passwordField).enterText(password);
      await $(#loginButton).tap();

      await $.waitUntilVisible($(#homeScreenTitle));

      expect($(#homeScreenTitle).text, equals('Welcome'));
    },
  );
}
```

Key concepts:

* Use `patrolTest()` instead of `testWidgets()`.
* `$` is the Patrol tester.
* Use `$(#keyName)` to find widgets by `Key`.
* Use explicit wait conditions (e.g., `waitUntilVisible`).

### 3. Handle native dialogs

For OS-level permission dialogs:

```dart
patrolTest('grants camera permission', ($) async {
  await $.pumpWidgetAndSettle(const MyApp());

  await $(#openCameraButton).tap();

  if (await $.native.isPermissionDialogVisible()) {
    await $.native.grantPermission();
  }

  await $.waitUntilVisible($(#cameraPreview));
});
```

Use native automation only when required by the feature.

### 4. Selector & interaction quick reference

**Finding widgets:**

```dart
$('some text')        // by text
$(TextField)          // by type
$(Icons.arrow_back)   // by icon
```

**Tapping:**

```dart
// Tap a widget containing a specific text label
await $(Container).$('click').tap();

// Tap a container that contains an ElevatedButton
await $(Container).containing(ElevatedButton).tap();

// Tap only the enabled ElevatedButton
await $(ElevatedButton)
    .which<ElevatedButton>(
      (b) => b.enabled,
    )
    .tap();
```

**Entering text:**

```dart
// Enter text into the second TextField on screen
await $(TextField).at(1).enterText('your input');
```

**Scrolling:**

```dart
await $(widget_you_want_to_scroll_to).scrollTo();
```

**Native interactions:**

```dart
// Grant permission while app is in use
await $.native.grantPermissionWhenInUse();

// Open notification shade and tap a notification by text
await $.native.openNotifications();
await $.native.tapOnNotificationBySelector(
  Selector(textContains: 'text'),
);
```

### 5. Running Patrol tests

Run all tests:

```bash
patrol test
```

Run a specific file with live reload (development mode):

```bash
patrol develop -t integration_test/my_test.dart
```

Run a specific file:

```bash
patrol test --target patrol_test/login_test.dart
```

Run on web:

```bash
patrol test --device chrome
```

Headless web (CI):

```bash
patrol test --device chrome --web-headless true
```

Filter by tags:

```bash
patrol test --tags android
```

### 6. Stabilization patterns

Flaky tests undermine confidence. Apply these patterns:

```dart
// AVOID — arbitrary delay
await Future.delayed(Duration(seconds: 3));

// PREFER — explicit wait condition
await $.waitUntilVisible($(#targetWidget));

// For animations, pump until settled
await $.pumpAndSettle();
```

* Never use `Future.delayed` as a synchronization mechanism.
* Use `waitUntilVisible` or `waitUntilExists` to wait for UI state.
* Set `settleTimeout` in `PatrolTesterConfig` for slow CI environments.

### Output requirements

When applied, this skill produces:

1. Patrol test(s) covering the specified feature.
2. Any required widget `Key` additions to production code.
3. Exact `patrol test` command(s) to execute locally.
4. Notes explaining stabilization or timing decisions.

**Checkpoint:** Run `patrol test --target <file>` locally to confirm the test passes before committing.

### Quality bar

A valid Patrol test must be:

* **Deterministic** — no arbitrary delays; uses explicit wait conditions.
* **Readable** — clear test name describing the user journey.
* **Minimal but complete** — one assertion chain per journey.
* **Secret-safe** — credentials loaded from `String.fromEnvironment`, never hardcoded.
* **CI-ready** — passes headless with `--web-headless true` or on emulator.