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c2b7eb3 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 | import type { ActionReducerMapBuilder, Reducer } from '@reduxjs/toolkit'
import { createAction, createReducer } from '@reduxjs/toolkit'
describe('type tests', () => {
test('createReducer() infers type of returned reducer.', () => {
const incrementHandler = (
state: number,
action: { type: 'increment'; payload: number },
) => state + 1
const decrementHandler = (
state: number,
action: { type: 'decrement'; payload: number },
) => state - 1
const reducer = createReducer(0 as number, (builder) => {
builder
.addCase('increment', incrementHandler)
.addCase('decrement', decrementHandler)
})
expectTypeOf(reducer).toMatchTypeOf<Reducer<number>>()
expectTypeOf(reducer).not.toMatchTypeOf<Reducer<string>>()
})
test('createReducer() state type can be specified explicitly.', () => {
const incrementHandler = (
state: number,
action: { type: 'increment'; payload: number },
) => state + action.payload
const decrementHandler = (
state: number,
action: { type: 'decrement'; payload: number },
) => state - action.payload
createReducer(0 as number, (builder) => {
builder
.addCase('increment', incrementHandler)
.addCase('decrement', decrementHandler)
})
// @ts-expect-error
createReducer<string>(0 as number, (builder) => {
expectTypeOf(builder.addCase)
.parameter(1)
.not.toMatchTypeOf(incrementHandler)
expectTypeOf(builder.addCase)
.parameter(1)
.not.toMatchTypeOf(decrementHandler)
})
})
test('createReducer() ensures state type is mutable within a case reducer.', () => {
const initialState: { readonly counter: number } = { counter: 0 }
createReducer(initialState, (builder) => {
builder.addCase('increment', (state) => {
state.counter += 1
})
})
})
test('builder callback for actionMap', () => {
const increment = createAction<number, 'increment'>('increment')
const reducer = createReducer(0, (builder) =>
expectTypeOf(builder).toEqualTypeOf<ActionReducerMapBuilder<number>>(),
)
expectTypeOf(reducer(0, increment(5))).toBeNumber()
expectTypeOf(reducer(0, increment(5))).not.toBeString()
})
})
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