GodsBoss / redux-reducer-map

describe('Reducer created via Redux Reducer Map', () => {

  const EMPTY_STATE = {}

  it('returns the initial state if given none', () => {

    const initialState = { foo: 'bar' }

    const reducerMap = {}

    const action = { type: 'NOP' }

    const reducedState = createReducerViaMap(reducerMap, initialState)(undefined, action)

    expect(reducedState).to.eql(initialState)

  })

  it('passes state and action to the appropriate function of the map', () => {

    const reducerMap = {

      USED: (state, action) => ({ reducer: 'USED', action: action, state: state }),

    }

    const reduce = createReducerViaMap(reducerMap, EMPTY_STATE)

    const STATE_VALUE = 1500

    const ACTION_VALUE = 2500

    const state = { value: STATE_VALUE }

    const action = { type: 'USED', value: ACTION_VALUE }

    const reducedState = reduce(state, action)

    expect(reducedState.reducer).to.be('USED')

    expect(reducedState.state.value).to.be(STATE_VALUE)

    expect(reducedState.action.value).to.be(ACTION_VALUE)

  })

  it('throws an error by default if action type is not found', () => {

    const UNKNOWN_ACTION_TYPE = 'UNKNOWN'

    const reducerMap = {}

    const reduce = createReducerViaMap(reducerMap, EMPTY_STATE)

    const state = { value: 'Some value' }

    const action = { type: UNKNOWN_ACTION_TYPE }

    const usingUnknownActionType = () => {

      reduce(state, action)

    }

    expect(usingUnknownActionType).to.throwException((e) => {

      expect(e.message).to.contain(UNKNOWN_ACTION_TYPE)

      expect(e.state).to.eql(state)

      expect(e.action).to.eql(action)

    })

  })

  it('allows overriding default error handling behaviour on unknown action types', () => {

    const UNKNOWN_ACTION_TYPE = 'UNKNOWN'

    const reducerMap = {}

    const customErrorHandler = (state, action) => (

      {

        state: state,

        action: action

      }

    )

    const reduce = createReducerViaMap(reducerMap, EMPTY_STATE, customErrorHandler)

    const state = { value: 42 }

    const action = { type: UNKNOWN_ACTION_TYPE, value: 666 }

    const reducedState = reduce(state, action)

    expect(reducedState.state).to.eql(state)

    expect(reducedState.action).to.eql(action)

  })

  it('provides a convenience error handler for returning the state unchanged', () => {

    const UNKNOWN_ACTION_TYPE = 'UNKNOWN'

    const reducerMap = {}

    const reduce = createReducerViaMap(reducerMap, EMPTY_STATE, createReducerViaMap.justReturnState)

    const state = { value: 42 }

    const action = { type: UNKNOWN_ACTION_TYPE, value: 666 }

    const reducedState = reduce(state, action)

    expect(reducedState).to.eql(state)

  })

  it("returns the initial state when given redux's init action", () => {

    const action = { type: '@@redux/INIT' }

    const reducerMap = {}

    const initialState = { value: 666 }

    const reduce = createReducerViaMap(reducerMap, initialState)

    const reducedState = reduce(EMPTY_STATE, action)

    expect(reducedState).to.eql(initialState)

  })

  it("lets the user override the reducer for redux's init action", () => {

    const action = { type: '@@redux/INIT' }

    const reducerMap = {

      '@@redux/INIT': (state, action) => ({ originalState: state, action })

    }

    const reduce = createReducerViaMap(reducerMap, EMPTY_STATE)

    const reducedState = reduce(EMPTY_STATE, action)

    expect(reducedState.action).to.eql(action)

    expect(reducedState.originalState).to.eql(EMPTY_STATE)

  })

})