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A Dart package that makes testing controllers easy. Built to work with getbloc.

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Unit Test with testController

testController creates a new controller-specific test case with the given description. testController will handle asserting that the controller emits the expected states (in order) after act is executed. testController also handles ensuring that no additional states are emitted by closing the controller stream before evaluating the expectation.

build should be used for all controller initialization and preparation and must return the controller under test.

seed is an optional Function that returns a state which will be used to seed the controller before act is called.

act is an optional callback which will be invoked with the controller under test and should be used to interact with the controller.

skip is an optional int which can be used to skip any number of states. skip defaults to 0.

wait is an optional Duration which can be used to wait for async operations within the controller under test such as debounceTime.

expect is an optional Function that returns a Matcher which the controller under test is expected to emit after act is executed.

verify is an optional callback which is invoked after expect and can be used for additional verification/assertions. verify is called with the controller returned by build.

errors is an optional Function that returns a Matcher which the controller under test is expected to throw after act is executed.

group('CounterController', () {
  testController(
    'emits [] when nothing is added',
    build: () => CounterController(),
    expect: () => [],
  );

  testController(
    'emits [1] when CounterEvent.increment is added',
    build: () => CounterController(),
    act: (controller) => controller.add(CounterEvent.increment),
    expect: () => [1],
  );
});

testController can optionally be used with a seeded state.

testController(
  'CounterController emits [10] when seeded with 9',
  build: () => CounterController(),
  seed: () => 9,
  act: (controller) => controller.increment(),
  expect: () => [10],
);

testController can also be used to skip any number of emitted states before asserting against the expected states. The default value is 0.

testController(
  'CounterController emits [2] when CounterEvent.increment is added twice',
  build: () => CounterController(),
  act: (controller) => controller..add(CounterEvent.increment)..add(CounterEvent.increment),
  skip: 1,
  expect: () => [2],
);

testController can also be used to wait for async operations like debounceTime by providing a Duration to wait.

testController(
  'CounterController emits [1] when CounterEvent.increment is added',
  build: () => CounterController(),
  act: (controller) => controller.add(CounterEvent.increment),
  wait: const Duration(milliseconds: 300),
  expect: () => [1],
);

testController can also be used to verify internal controller functionality.

testController(
  'CounterController emits [1] when CounterEvent.increment is added',
  build: () => CounterController(),
  act: (controller) => controller.add(CounterEvent.increment),
  expect: () => [1],
  verify: (_) {
    verify(() => repository.someMethod(any())).called(1);
  }
);

testController can also be used to expect that exceptions have been thrown.

testController(
  'CounterController throws Exception when null is added',
  build: () => CounterController(),
  act: (controller) => controller.add(null),
  errors: () => [isA<Exception>()]
);

Note: when using testController with state classes which don't override == and hashCode you can provide an Iterable of matchers instead of explicit state instances.

testController(
  'emits [StateB] when MyEvent is added',
  build: () => MyController(),
  act: (controller) => controller.add(MyEvent()),
  expect: () => [isA<StateB>()],
);