[image_picker] Add native tests for pick results, camera access, and presentation

[victogomez-cs]

Adds native unit tests for previously untested paths in FLTImagePickerPlugin.m (pick-result handling, camera authorization, and presentation) before the Objective-C → Swift migration. Production code is unchanged. New cases follow the existing StubViewProvider / OCMock conventions in ImagePickerPluginTests.m.

This is a tests-only change, so it does not bump the package version or CHANGELOG.

ImagePickerPluginTests go from 33 tests to 52 tests (+19).

New test cases

Pick results / dismiss:

• testPickImageInvalidResultWhenMultiplePathsReturned — image pick with multiple paths uses the existing invalid_result double-completion behavior
• testPickVideoInvalidResultWhenMultiplePathsReturned — same for video pick
• testPHPickerCancelSendsEmptyPathList — PHPicker cancel completes with an empty path list
• testPresentationControllerDidDismissSendsEmptyPathList — dismiss completes with an empty path list

Image quality:

• testDesiredImageQualityClampsOutOfRangeValues — quality below 0 is clamped
• testDesiredImageQualityScalesValidPercent — a valid percent is scaled
• testDesiredImageQualityOver100IsClamped — quality above 100 is clamped

Camera access:

• testCameraAccessDeniedReturnsError — denied authorization returns an error
• testCameraAccessRestrictedReturnsError — restricted authorization returns an error
• testCameraAccessNotDeterminedDenied — prompt denied returns an error
• testCameraAccessNotDeterminedGrantedPresentsCamera — prompt granted presents the camera
• testCameraAccessUnknownStatusTreatedAsDenied — unknown status is treated as denied
• testShowCameraWhenUnavailableSendsNilPathList — unavailable camera completes with a nil path list
• testShowCameraReturnsEarlyWhenAlreadyBeingPresented — a second present is a no-op
• testShowCameraUnavailableAlertOKHandler — the unavailable-camera alert OK handler runs

Presentation / blocker window:

• testPresentingViewControllerWithoutWindowReturnsHostController — no window returns the host view controller
• testPresentingViewControllerReusesExistingBlockerWindow — an existing interaction-blocker window is reused
• testPresentingViewControllerWithoutWindowSceneUsesFrame — missing window scene falls back to a frame
• testDefaultViewProviderReturnsRegistrarViewController — the default view provider returns the registrar’s view controller

Second part of image_picker_ios coverage backfill before the Obj-C → Swift migration for flutter/flutter#119107

Pre-Review Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the AI contribution guidelines and understand my responsibilities, or I am not using AI tools.
• I read the Tree Hygiene page, which explains my responsibilities.
• I read and followed the relevant style guides and ran the auto-formatter.
• I signed the CLA.
• The title of the PR starts with the name of the package surrounded by square brackets, e.g. [shared_preferences]
• I linked to at least one issue that this PR fixes in the description above.
• I followed the version and CHANGELOG instructions, using semantic versioning and the repository CHANGELOG style, or I have commented below to indicate which documented exception this PR falls under¹.
• I updated/added any relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or I have commented below to indicate which test exemption this PR falls under¹.
• All existing and new tests are passing.

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Footnotes

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[gemini-code-assist]

Code Review

This pull request adds comprehensive unit tests to ImagePickerPluginTests.m covering image and video picking results, camera access permissions, image quality clamping, and view controller presentation. The review feedback suggests refactoring several tests to avoid relying on UIApplication.sharedApplication.connectedScenes and real UIWindow instances, recommending instead the use of mock view controllers or initializing UIWindow with a simple frame to ensure tests are robust and run reliably in headless environments.

[gemini-code-assist]

Relying on UIApplication.sharedApplication.connectedScenes and creating/making key a real UIWindow is fragile, slow, and will fail in headless environments or logic tests where no active scene or host application window exists. Instead, you can use a mock UIViewController to capture and verify the presented UIAlertController and its action handler directly. This is faster, more robust, and completely independent of the window hierarchy.

  id mockViewController = OCMClassMock([UIViewController class]);
  __block UIAlertController *alert = nil;
  OCMStub([mockViewController presentViewController:[OCMArg any] animated:YES completion:nil])
      .andDo(^(NSInvocation *invocation) {
        [invocation getArgument:&alert atIndex:2];
      });

  FLTImagePickerPlugin *plugin = [[FLTImagePickerPlugin alloc]
      initWithViewProvider:[[StubViewProvider alloc] initWithViewController:mockViewController]];
  [plugin setImagePickerControllerOverrides:@[ [[UIImagePickerController alloc] init] ]];

  XCTestExpectation *resultExpectation = [self expectationWithDescription:@"unavailable"];
  [plugin pickImageWithSource:[FLTSourceSpecification makeWithType:FLTSourceTypeCamera
                                                            camera:FLTSourceCameraRear]
                      maxSize:[[FLTMaxSize alloc] init]
                      quality:nil
                 fullMetadata:YES
                   completion:^(NSString *result, FlutterError *error) {
                     XCTAssertNil(result);
                     [resultExpectation fulfill];
                   }];
  [self waitForExpectationsWithTimeout:30 handler:nil];

  XCTAssertTrue([alert isKindOfClass:[UIAlertController class]]);
  void (^handler)(UIAlertAction *) = [alert.actions.firstObject valueForKey:@"handler"];
  if (handler) {
    handler(alert.actions.firstObject);
  }

[victogomez-cs]

Agreed and fixed. This test now uses an OCMock UIViewController to capture the presented UIAlertController instead of creating a real key window from UIApplication.sharedApplication.connectedScenes.

[gemini-code-assist]

Using UIApplication.sharedApplication.connectedScenes to initialize the UIWindow is fragile and will fail in headless environments or logic tests where connectedScenes is empty. You can initialize the UIWindow with a simple frame instead, which is fully supported and doesn't rely on active scenes or host application state.

Suggested change

	UIWindowScene *scene =
	(UIWindowScene *)UIApplication.sharedApplication.connectedScenes.allObjects.firstObject;
	UIWindow *window = [[UIWindow alloc] initWithWindowScene:scene];
	window.frame = scene.coordinateSpace.bounds;
	UIViewController *rootViewController = [[UIViewController alloc] init];
	window.rootViewController = rootViewController;
	[rootViewController loadViewIfNeeded];
	[window makeKeyAndVisible];
	UIWindow *window = [[UIWindow alloc] initWithFrame:CGRectMake(0, 0, 320, 480)];
	UIViewController *rootViewController = [[UIViewController alloc] init];
	window.rootViewController = rootViewController;
	[rootViewController loadViewIfNeeded];

[victogomez-cs]

Agreed and fixed. The window is now created with initWithFrame: so the test doesn’t depend on an active UIWindowScene.

[gemini-code-assist]

By initializing the UIWindow with initWithFrame:, the window's windowScene is nil by default on iOS 13+. This allows you to test the fallback frame path directly without needing to query connectedScenes, instantiate a scene, or use OCMPartialMock to stub windowScene to return nil.

Suggested change

	UIWindowScene *scene =
	(UIWindowScene *)UIApplication.sharedApplication.connectedScenes.allObjects.firstObject;
	UIWindow *window = [[UIWindow alloc] initWithWindowScene:scene];
	window.frame = scene.coordinateSpace.bounds;
	UIViewController *rootViewController = [[UIViewController alloc] init];
	window.rootViewController = rootViewController;
	[rootViewController loadViewIfNeeded];
	[window makeKeyAndVisible];
	id mockWindow = OCMPartialMock(window);
	OCMStub([mockWindow windowScene]).andReturn(nil);
	FLTImagePickerPlugin *plugin = [[FLTImagePickerPlugin alloc]
	initWithViewProvider:[[StubViewProvider alloc] initWithViewController:rootViewController]];
	XCTAssertNotNil([plugin presentingViewControllerForImagePickerInNewWindow]);
	[plugin removeInteractionBlocker];
	[mockWindow stopMocking];
	UIWindow *window = [[UIWindow alloc] initWithFrame:CGRectMake(0, 0, 320, 480)];
	UIViewController *rootViewController = [[UIViewController alloc] init];
	window.rootViewController = rootViewController;
	[rootViewController loadViewIfNeeded];
	FLTImagePickerPlugin *plugin = [[FLTImagePickerPlugin alloc]
	initWithViewProvider:[[StubViewProvider alloc] initWithViewController:rootViewController]];
	XCTAssertNotNil([plugin presentingViewControllerForImagePickerInNewWindow]);
	[plugin removeInteractionBlocker];

[victogomez-cs]

Agreed and fixed. initWithFrame: already leaves windowScene nil, so this covers the frame fallback without a partial mock.