Google Cloud Language V2 Tests

Testing with Fakes

Most unit tests should use fakes instead of making network requests to Google services.

• Code that uses LanguageService can be tested by injecting the fake FakeLanguageService.

Import the fakes from the testing library:

import 'package:google_cloud_language_v2/testing.dart';

Option A: Using Constructor Closures (Recommended)

You can inject behavior by passing optional function callbacks to the fake's constructor. Methods that are not provided will throw an UnsupportedError.

import 'package:google_cloud_language_v2/language.dart';
import 'package:google_cloud_language_v2/testing.dart';

final fake = FakeLanguageService(
  analyzeSentiment: (request) async {
    // Assert request contents here if needed.
    return AnalyzeSentimentResponse();
  },
);

Option B: Subclassing the Fake

For more complex test setups or shared states, you can subclass the fake and override its methods. Methods that are not overridden will throw an UnsupportedError.

import 'package:google_cloud_language_v2/language.dart';
import 'package:google_cloud_language_v2/testing.dart';

final class MyFakeLanguageService extends FakeLanguageService {
  @override
  Future<AnalyzeSentimentResponse> analyzeSentiment(
    AnalyzeSentimentRequest request,
  ) async {
    // Assert request contents here if needed.
    return AnalyzeSentimentResponse();
  }
}

A Simple Test

import 'package:google_cloud_language_v2/language.dart';
import 'package:google_cloud_language_v2/testing.dart';
import 'package:test/test.dart';

Future<void> functionUnderTest(LanguageService service) async {
  // Application logic here.
  await service.analyzeSentiment(AnalyzeSentimentRequest());
  // More application logic here.
}

void main() {
  test('test', () async {
    final fake = FakeLanguageService(
      analyzeSentiment: (request) async {
          // Assert request contents here.
          return AnalyzeSentimentResponse();
      },
    );
    // Instead of verifying that `functionUnderTest` completes, you should verify
    // the relevant properties of the result.
    await expectLater(functionUnderTest(fake), completes);
  });
}