Comparison of the generated selection functions

Hi, i’m having some problems with comparison of the select functions: This is begining of my saga:

    export function* mySaga() {
        const { data } = yield select(componentSelectors.getComponent(componentId))
        
        /** some logick */
    }

and a test for her:

    it('Testing mySaga', () => {
        const componentId = 1;
        testSaga(mySaga)
            .next()
            .select(componentSelectors.getComponent(componentId))

            /** test continuation */
    });

When I run the test, I get an error: “select effects do not match”

    Expected
    --------
    { selector: [Function: bound ], args: [] }

    Actual
    ------
    { selector: [Function: bound ], args: [] }

And so it happens to all tests, where i’m using generated selector getComponent and other like him:

    const getComponents = state => state["components"];
    const getComponent = id => state => {
        const { [id]: component } = getComponents(state);
        return component;
    };
    export const componentSelectors= {
        getComponents,
        getComponent
        }
    }

Can I somehow use your library to compare the generated functions?

[arnaudambro]

@pavel-rakhmanov I encountered the same issue, this is how I solved it:

import componentSelectors from '../selectors'
jest('../selectors')

it('Testing mySaga', () => {
  beforeAll(() => {
    const noOp = () => {}
    componentSelectors.getComponent.mockImplementation(() => noOp)
  })
  const componentId = 1;
  testSaga(mySaga)
      .next()
      .select(componentSelectors.getComponent(componentId))
      .next(/* component */)
      .isDone()
});

[cdow]

Another option that doesn’t involve any mocking is you can wrap the creation of your generated function with a call. This results in the original function looking like this:

export function* mySaga() {
  const componentSelector = yield call(componentSelectors.getComponent, componentId);
  const { data } = yield select(componentSelector);
        
  /** some logic */
}

This can then be tested with:

it('Testing mySaga', () => {
  const componentId = 1;
  const componentSelector = () => {};
  
  testSaga(mySaga)
    .next()
    .call(componentSelectors.getComponent, componentId)
    .next(componentSelector)
    .select(componentSelector)

    /** test continuation */
});