Issue with Jest tests

[bellmoose]

The transform works well when I use it in my application, but it fails when running my unit tests declaring that it is not a function. Is there a specific setup step that needs to be performed when using Jest?

[ChildishDanbino]

@bellmoose - You didn't provide much info on what your code looks like but I was running into the same issue so i'll try and walk you through it as well as leave this here for others:

When you create a transform you are getting back an object that has three functions not a function itself.... Inbound, Outbound, and Config. Depending on your transform you'll need to test them individually. Below is my code for a really simple transform that blacklists "account.loading" from being persisted.

Transform:

export const accountBlackList = createTransform(
  (reducer, key) => {
    if (key !== 'account') {
      return reducer;
    }
    return {
      ...reducer,
      loading: undefined
    };
  }
);

export default accountBlackList;

Unit Test with 100% Coverage:

import { accountBlackList } from '../../../src/redux/transforms/account';
import { initialState } from '../../../src/redux/modules/account';

describe('transforms: account', () => {
  it('should return loading undefined for account reducer', () => {
    const result = accountBlackList.in(initialState, 'account');
    expect(result.loading).toEqual(undefined);
  });

  it('should return reducer as in when not account', () => {
    const result = accountBlackList.in(initialState, 'prices');
    expect(result).toEqual(initialState);
  });
});