Mocking actions and reducers

To mock an action and its reducer, create a MockStore instead of a regular Store.

The MockStore has a mocks parameter which is a map where the keys are action types, and the values are the mocks. For example:

var store = MockStore<AppState>(
  initialState: initialState,  
  mocks: {
     MyAction1 : ...
     MyAction2 : ...
     ...
  },
);

There are 5 different ways to define mocks:

Use null to disable dispatching the action of a certain type:
```
mocks: {
   MyAction : null
}
```

Use a MockAction<St> instance to dispatch this mock action instead, and provide the original action as a getter to the mock action.

class MyAction extends ReduxAction<AppState> {
  String url;
  MyAction(this.url);
  Future<AppState> reduce() => get(url);
}      

class MyMockAction extends MockAction<AppState> {  
  Future<AppState> reduce() async {                  
    String url = (action as MyAction).url;
    if (url == 'https://example.com') return 123;
    else if (url == 'https://flutter.io') return 345;
    else return 678;
  }
}

mocks: {
   MyAction : MyMockAction()
}

Use a ReduxAction<St> instance to dispatch this mock action instead.

class MyAction extends ReduxAction<AppState> {
  String url;            
  MyAction(this.url);
  Future<AppState> reduce() => get(url);
}

class MyMockAction extends ReduxAction<AppState> {  
  Future<AppState> reduce() async => 123;
}

mocks: {
   MyAction : MyMockAction()
}

Use a ReduxAction<St> Function(ReduxAction<St>) to create a mock from the original action.

class MyAction extends ReduxAction<AppState> {
  String url;        
  MyAction(this.url);
  Future<AppState> reduce() => get(url);
}

class MyMockAction extends MockAction<AppState> {
  String url;
  MyMockAction(this.url);  
  Future<AppState> reduce() async {                     
    if (url == 'https://example.com') return 123;
    else if (url == 'https://flutter.io') return 345;
    else return 678;
  }
}

mocks: {
   MyAction : (MyAction action) => MyMockAction(action.url)
}

Use a St Function(ReduxAction<St>, St) or Future<St> Function(ReduxAction<St>, St) to modify the state directly.

class MyAction extends ReduxAction<AppState> {
  String url;        
  MyAction(this.url);
  Future<AppState> reduce() => get(url);
}

mocks: {
   MyAction : (MyAction action, AppState state) async {
      if (action.url == 'https://example.com') return 123;
      else if (action.url == 'https://flutter.io') return 345;
      else return 678;
   }
}

You can also change the mocks after a store is created, by using the following methods of the MockStore and StoreTester classes:

MockStore<St> addMock(Type actionType, dynamic mock);
MockStore<St> addMocks(Map<Type, dynamic> mocks);
MockStore<St> clearMocks();