Can't Compare FormData Objects and Write Tests in Dio Library

[bartosz-timecamp]

Package

dio

Version

5.2.1

Output of flutter doctor -v

[!] Flutter (Channel stable, 3.10.1, on macOS 13.4.1 22F82 darwin-arm64, locale en-PL)
    • Flutter version 3.10.1 on channel stable at /Users/bartosz/fvm/versions/3.10.1
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision d3d8effc68 (7 weeks ago), 2023-05-16 17:59:05 -0700
    • Engine revision b4fb11214d
    • Dart version 3.0.1
    • DevTools version 2.23.1

[✗] Android toolchain - develop for Android devices
    ✗ Unable to locate Android SDK.
      Install Android Studio from: https://developer.android.com/studio/index.html
      On first launch it will assist you in installing the Android SDK components.
      (or visit https://flutter.dev/docs/get-started/install/macos#android-setup for detailed instructions).
      If the Android SDK has been installed to a custom location, please use
      `flutter config --android-sdk` to update to that location.


[✓] Xcode - develop for iOS and macOS (Xcode 14.3)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 14E222b
    • CocoaPods version 1.11.3

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[!] Android Studio (not installed)
    • Android Studio not found; download from https://developer.android.com/studio/index.html
      (or visit https://flutter.dev/docs/get-started/install/macos#android-setup for detailed instructions).

[✓] IntelliJ IDEA Community Edition (version 2022.3)
    • IntelliJ at /Applications/IntelliJ IDEA CE.app
    • Flutter plugin version 71.0.6
    • Dart plugin version 223.7571.203

[✓] Connected device (2 available)
    • macOS (desktop) • macos  • darwin-arm64   • macOS 13.4.1 22F82 darwin-arm64
    • Chrome (web)    • chrome • web-javascript • Google Chrome 114.0.5735.198

[✓] Network resources
    • All expected network resources are available.

Dart Version

3.0.1

Steps to Reproduce

About the problem

The main problem I am facing right now is being unable to write a unit test for one of the POST endpoints. It requires passing FormData, but I can't compare FormData to another FormData. This limitation prevents me from writing the unit test, and I encounter the following error:

Assertion failed: "Could not find mocked route matching request
for POST /internal/api/v3/screenshot/push { data: Instance of 'FormData',
query parameters: {}, headers: {content-type: multipart/form-data;
boundary=--dio-boundary-0598433441, accept: application/json,
content-length: 294} }"

Code

Here's the code related to the issue:

@immutable
class CreateScreenshotRequest {

  const CreateScreenshotRequest({
    required this.createdAt,
    required this.screenshotBytes,
  });

  FormData toFormData() {
    return FormData.fromMap({
      'created_at': createdAt.toString(),
      'screenshot': MultipartFile.fromBytes(
        screenshotBytes,
        filename: 'name',
      ),
    });
  }

  final DateTime createdAt;

  final Uint8List screenshotBytes;

  @override
  bool operator ==(Object other) =>
      other is CreateScreenshotRequest &&
      createdAt == other.createdAt &&
      listEquals(screenshotBytes, other.screenshotBytes);

  @override
  int get hashCode => createdAt.hashCode ^ screenshotBytes.hashCode;
}

Here's how the unit test looks like:

  test('No data is returned when HTTP call is successful', () async {
    dioAdapter.onPost(
      path,
      (server) => server.reply(200, ''),
      data: createScreenshotRequest.toFormData(),
      headers: _getRequestHeaders(),
    );

    final response = await apiClient.sendScreenshot(
      request: createScreenshotRequest,
    );
    expect(response, isA<Success>());
  });

Expected Result

The main problem I am facing right now is being unable to compare FormData objects directly. The Dio library does not provide a built-in comparison method or operator overload for FormData. However, it is important for me to be able to compare one FormData object to another.

Actual Result

final createScreenshotRequest = CreateScreenshotRequest(
  createdAt: DateTime(2023, 1, 1, 10),
  screenshotBytes: Uint8List.fromList([1, 2, 3, 4, 5]),
);
final secondCreateScreenshotRequest = CreateScreenshotRequest(
  createdAt: DateTime(2023, 1, 1, 10),
  screenshotBytes: Uint8List.fromList([1, 2, 3, 4, 5]),
);

expect(
   createScreenshotRequest.toFormData(),
   secondCreateScreenshotRequest.toFormData(),
 );

package:matcher expect
package:flutter_test/src/widget_tester.dart 459:16 expect
test/client/tc_api_client_test.dart 1351:7 main..
Expected: <Instance of 'FormData'>
Actual: <Instance of 'FormData'>

[kuhnroyal]

Are you using http-mock-adapter to test? It has a matcher for FormData.

[bartosz-timecamp]

I couldn't find this in the package (http_mock_adapter: ^0.4.4). Could you show it?

[AlexV525]

I couldn't find this in the package (http_mock_adapter: ^0.4.4). Could you show it?

https://github.com/lomsa-dev/http-mock-adapter/blob/main/lib/src/matchers/form_data.dart

[AlexV525]

Closing as #1888 (comment).