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import { act, renderHook } from '@testing-library/react-hooks';
import logger from 'redux-logger';
import thunk from 'redux-thunk';
import createReducer from '../src/factory/createReducer';
it('should init reducer hook function', () => {
const useSomeReducer = createReducer();
expect(useSomeReducer).toBeInstanceOf(Function);
});
/**
* This test suite implements the special demo in storybook that creates a
* reducer with thunk and logger for using a simple counter
*/
describe('when using created reducer hook', () => {
const initialCount = 1;
let originalLog;
let originalGroup;
const mockLog = jest.fn();
const mockGroup = jest.fn();
function reducer(state, action) {
switch (action.type) {
case 'increment':
return { count: state.count + 1 };
case 'decrement':
return { count: state.count - 1 };
case 'reset':
return { count: action.payload };
default:
throw new Error();
}
}
// Action creator to increment count, wait a second and then reset
const addAndReset = () => {
return (dispatch) => {
dispatch({ type: 'increment' });
setTimeout(() => {
dispatch({ type: 'reset', payload: initialCount });
}, 1000);
};
};
const setUp = () => {
const useThunkReducer = createReducer(thunk, logger);
return renderHook(() => useThunkReducer(reducer, { count: initialCount }));
};
beforeAll(() => {
originalLog = console.log;
originalGroup = console.group;
console.log = mockLog;
console.group = mockGroup;
});
beforeEach(() => {
jest.useFakeTimers();
});
afterAll(() => {
console.log = originalLog;
console.group = originalGroup;
});
it('should init state and dispatcher', () => {
const { result } = setUp();
const [state, dispatch] = result.current;
expect(state).toEqual({ count: 1 });
expect(dispatch).toBeInstanceOf(Function);
});
it.each`
actionType | expectedCount | payload
${'increment'} | ${2} | ${undefined}
${'decrement'} | ${0} | ${undefined}
${'reset'} | ${1} | ${1}
`('should handle "$actionType" action', ({ actionType, expectedCount, payload }) => {
const { result } = setUp();
const [, dispatch] = result.current;
expect(mockLog).not.toHaveBeenCalled();
act(() => {
dispatch({ type: actionType, payload });
});
expect(result.current[0]).toEqual({ count: expectedCount });
expect(mockLog).toHaveBeenCalled();
});
it('should handle async action with several middlewares', () => {
const { result } = setUp();
const [, dispatch] = result.current;
expect(mockLog).not.toHaveBeenCalled();
act(() => {
dispatch(addAndReset());
});
expect(result.current[0]).toEqual({ count: 2 });
expect(mockLog).toHaveBeenCalled();
// fast-forward until all timers have been executed
act(() => {
jest.runAllTimers();
});
expect(result.current[0]).toEqual({ count: 1 });
});
});
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