unittest 0.11.5+4

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Support for writing unit tests in Dart.

See also: [Unit Testing with Dart] (http://www.dartlang.org/articles/dart-unit-tests/)

##Concepts

• Tests: Tests are specified via the top-level function [test], they can be organized together using [group].

• Checks: Test expectations can be specified via [expect]

• Matchers: [expect] assertions are written declaratively using the [Matcher] class.

• Configuration: The framework can be adapted by setting [unittestConfiguration] with a [Configuration]. See the other libraries in the unittest package for alternative implementations of [Configuration] including compact_vm_config.dart, html_config.dart and html_enhanced_config.dart.

##Examples

A trivial test:

import 'package:unittest/unittest.dart';

void main() {
  test('this is a test', () {
    int x = 2 + 3;
    expect(x, equals(5));
  });
}

Multiple tests:

import 'package:unittest/unittest.dart';

void main() {
  test('this is a test', () {
    int x = 2 + 3;
    expect(x, equals(5));
  });
  test('this is another test', () {
    int x = 2 + 3;
    expect(x, equals(5));
  });
}

Multiple tests, grouped by category:

import 'package:unittest/unittest.dart';

void main() {
  group('group A', () {
    test('test A.1', () {
      int x = 2 + 3;
      expect(x, equals(5));
    });
    test('test A.2', () {
      int x = 2 + 3;
      expect(x, equals(5));
    });
  });
  group('group B', () {
    test('this B.1', () {
      int x = 2 + 3;
      expect(x, equals(5));
    });
  });
}

Asynchronous tests: if callbacks expect between 0 and 6 positional arguments, [expectAsync] will wrap a function into a new callback and will not consider the test complete until that callback is run. A count argument can be provided to specify the number of times the callback should be called (the default is 1).

import 'dart:async';
import 'package:unittest/unittest.dart';

void main() {
  test('callback is executed once', () {
    // wrap the callback of an asynchronous call with [expectAsync] if
    // the callback takes 0 arguments...
    Timer.run(expectAsync(() {
      int x = 2 + 3;
      expect(x, equals(5));
    }));
  });

  test('callback is executed twice', () {
    var callback = expectAsync(() {
      int x = 2 + 3;
      expect(x, equals(5));
    }, count: 2); // <-- we can indicate multiplicity to [expectAsync]
    Timer.run(callback);
    Timer.run(callback);
  });
}

There may be times when the number of times a callback should be called is non-deterministic. In this case a dummy callback can be created with expectAsync((){}) and this can be called from the real callback when it is finally complete.

A variation on this is [expectAsyncUntil], which takes a callback as the first parameter and a predicate function as the second parameter. After each time the callback is called, the predicate function will be called. If it returns false the test will still be considered incomplete.

Test functions can return [Future]s, which provide another way of doing asynchronous tests. The test framework will handle exceptions thrown by the Future, and will advance to the next test when the Future is complete.

import 'dart:async';
import 'package:unittest/unittest.dart';

void main() {
  test('test that time has passed', () {
    var duration = const Duration(milliseconds: 200);
    var time = new DateTime.now();

    return new Future.delayed(duration).then((_) {
      var delta = new DateTime.now().difference(time);

      expect(delta, greaterThanOrEqualTo(duration));
    });
  });
}