Testing Simple Actions

Consider the following simple actions, from the Redux chapter of this book:

import { Injectable } from '@angular/core';
import { NgRedux } from 'ng2-redux';
export const INCREMENT_COUNTER = 'INCREMENT_COUNTER';
export const DECREMENT_COUNTER = 'DECREMENT_COUNTER';
@Injectable
export class CounterActions {
constructor(private redux: NgRedux<any>) {}
increment() {
this.redux.dispatch({ type: INCREMENT_COUNTER });
}
decrement() {
this.redux.dispatch({ type: DECREMENT_COUNTER });
}
}

These are pretty straightforward to test:

import { NgRedux } from 'ng2-redux';
import {
CounterActions,
INCREMENT_COUNTER,
DECREMENT_COUNTER,
} from './counter';
// Mock out the NgRedux class with just enough to test what we want.
class MockRedux extends NgRedux<any> {
constructor() {
super(null);
}
dispatch = () => undefined;
}
describe('counter action creators', () => {
let actions: CounterActions;
let mockRedux: NgRedux<any>;
beforeEach(() => {
// Initialize mock NgRedux and create a new instance of the
// ActionCreatorService to be tested.
mockRedux = new MockRedux();
actions = new CounterActions(mockRedux);
});
it('increment should dispatch INCREMENT_COUNTER action', () => {
const expectedAction = {
type: INCREMENT_COUNTER
};
spyOn(mockRedux, 'dispatch');
actions.increment();
expect(mockRedux.dispatch).toHaveBeenCalled();
expect(mockRedux.dispatch).toHaveBeenCalledWith(expectedAction);
});
it('decrement should dispatch DECREMENT_COUNTER action', () => {
const expectedAction = {
type: DECREMENT_COUNTER
};
spyOn(mockRedux, 'dispatch');
actions.decrement();
expect(mockRedux.dispatch).toHaveBeenCalled();
expect(mockRedux.dispatch).toHaveBeenCalledWith(expectedAction);
});
});

We just make sure that our action creators do indeed dispatch the correct actions.