CODEWITHSUNDEEP
reduxreact-reduximmutability
gandalf
gandalf

Reputation: 53

How to deep-freeze redux state in react redux application?

I need to deep freeze the whole redux state in react redux application using deep-freeze library to check for any mutation on state. How should I use deep-freeze with react redux app to achieve this?

Upvotes: 3

Views: 3157

Answers (1)

Gerik
Gerik

Reputation: 736

I'm going to assume you mean you're looking to use deep-freeze as a testing tool for changes (as I'm not sure why you would want to freeze the entire state). All the while there a handful of examples out there.

Typically you use deep-freeze with expect and you focus on your reducers because reducers are given a state and they return an expected state.

A typical test usually looks something like this (taken from here):

// a test for the reducer
const testReducer = () => {
    const stateBefore = { value: 'foo' };
    const action = {
        type: 'SET_STATE',
        value: 'bar'
    };
    const stateAfter = { value: 'bar' };

    // cannot modify
    deepFreeze(stateBefore);
    deepFreeze(action);

    expect(store(stateBefore, action)).toEqual(stateAfter);
}

In this way, you're verifying that actions taken do not alter your state in any way.

Egghead.io also has a good video on this here.

Of course, the usage doesn't have to be limited to tests; you could introduce deep-freeze as an assertion tool throughout your code as well I supposed if you want. I've not personally got any experience doing that.

Upvotes: 5

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