Unit test redux reducer using it's own initial state

Question

I have a reducer with a default initial state defined like this:

const webReducer = (state = {
    fetched: false,
    data: {}
}, action) => {
    switch (action.type) {
        case "FETCH_DATA":
            state = {
                ...state,
                fetched: action.payload.fetched
            };

            state.data.push( action.payload.data );

            return state;
        break;
    }

    return state;
};

When I run a test to check for the initial state, it pass:

const initialState = {
    fetched: false,
    data: {}
};

it("Should have a default initial state", () => {
    expect( webReducer( undefined, {}) ).toEqual( initialState );
})

However, when I try to test adding data to the state, it return this error:

TypeError: state.data.push is not a function

This is how I'm doing the test:

const object = {
    fetched: true,
    data: {
        config: {size: 10}
    }
};

expect(
    webReducer( undefined, {
        type: "FETCH_DATA", 
        payload: object
    })
).toEqual( object );

Why am i getting this error now, if before i could pass the test just fine? I also tried to pass a default state, like this:

expect(
    webReducer( initialState, {
        type: "FETCH_DATA", 
        payload: object
    })
).toEqual( object );

But I'm getting the same error.

Abhishek Jain · Accepted Answer · 2017-04-11 15:40:26Z

1

You have initialised data as an empty object, which doesn't have a push function on it. Try replacing it with the below, and the test should pass alright.

state = {
fetched: false,
data: []

answered Apr 11, 2017 at 15:40

Abhishek Jain

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1 Comment

celsomtrindade Over a year ago

Had to made some adjustments to test with multiple dispatchs but I got the point! Thanks =D

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