import type { OutputSelector, Selector, SelectorArray, UnknownMemoizer } from 'reselect' import { unstable_autotrackMemoize as autotrackMemoize, createSelector, createSelectorCreator, lruMemoize, weakMapMemoize } from 'reselect' import { test } from 'vitest' import type { RootState } from './testUtils' import { addTodo, setupStore } from './testUtils' const store = setupStore() const EMPTY_ARRAY: [] = [] export const fallbackToEmptyArray = (array: T[]) => { return array.length === 0 ? EMPTY_ARRAY : array } const selectCompletedTodos = createSelector( [(state: RootState) => state.todos], todos => { return fallbackToEmptyArray(todos.filter(todo => todo.completed === true)) } ) const completedTodos = selectCompletedTodos(store.getState()) store.dispatch(addTodo({ title: '', description: '' })) test('empty array', () => { expect(completedTodos).toBe(selectCompletedTodos(store.getState())) }) test('identity', () => { const identity = any>(func: Func) => func const createNonMemoizedSelector = createSelectorCreator({ memoize: identity, argsMemoize: identity }) const nonMemoizedSelector = createNonMemoizedSelector( [(state: RootState) => state.todos], todos => todos.filter(todo => todo.completed === true), { devModeChecks: { inputStabilityCheck: 'never' } } ) nonMemoizedSelector(store.getState()) nonMemoizedSelector(store.getState()) nonMemoizedSelector(store.getState()) expect(nonMemoizedSelector.recomputations()).toBe(3) }) test.todo('Top Level Selectors', () => { type TopLevelSelectors = { [K in keyof State as K extends string ? `select${Capitalize}` : never]: Selector } const topLevelSelectors: TopLevelSelectors = { selectAlerts: state => state.alerts, selectTodos: state => state.todos, selectUsers: state => state.users } }) test.todo('Find Fastest Selector', () => { const store = setupStore() const selectTodoIds = createSelector( [(state: RootState) => state.todos], todos => todos.map(({ id }) => id) ) const findFastestSelector = ( selector: S, ...selectorArgs: Parameters ) => { const memoizeFuncs = [lruMemoize, weakMapMemoize, autotrackMemoize] const results = memoizeFuncs .map(memoize => { const alternateSelector = createSelector( selector.dependencies as [...SelectorArray], selector.resultFunc, { memoize } ) const start = performance.now() alternateSelector.apply(null, selectorArgs) const time = performance.now() - start return { name: memoize.name, time, selector: alternateSelector } }) .sort((a, b) => a.time - b.time) const fastest = results.reduce((minResult, currentResult) => currentResult.time < minResult.time ? currentResult : minResult ) const ratios = results .filter(({ time }) => time !== fastest.time) .map( ({ time, name }) => `\x1B[33m \x1B[1m${ time / fastest.time }\x1B[0m times faster than \x1B[1;41m${name}\x1B[0m.` ) if (fastest.selector.memoize.name !== selector.memoize.name) { console.warn( `The memoization method for \x1B[1;41m${ selector.name }\x1B[0m is \x1B[31m${ selector.memoize.name }\x1B[0m!\nChange it to \x1B[32m\x1B[1m${ fastest.selector.memoize.name }\x1B[0m to be more efficient.\nYou should use \x1B[32m\x1B[1m${ fastest.name }\x1B[0m because it is${ratios.join('\nand\n')}` ) } return { results, fastest } as const } }) test('TypedCreateSelector', () => { type TypedCreateSelector< State, MemoizeFunction extends UnknownMemoizer = typeof weakMapMemoize, ArgsMemoizeFunction extends UnknownMemoizer = typeof weakMapMemoize > = < InputSelectors extends readonly Selector[], Result, OverrideMemoizeFunction extends UnknownMemoizer = MemoizeFunction, OverrideArgsMemoizeFunction extends UnknownMemoizer = ArgsMemoizeFunction >( ...createSelectorArgs: Parameters< typeof createSelector< InputSelectors, Result, OverrideMemoizeFunction, OverrideArgsMemoizeFunction > > ) => ReturnType< typeof createSelector< InputSelectors, Result, OverrideMemoizeFunction, OverrideArgsMemoizeFunction > > const createAppSelector: TypedCreateSelector = createSelector const selector = createAppSelector( [state => state.todos, (state, id: number) => id], (todos, id) => todos.find(todo => todo.id === id)?.completed ) }) test('createCurriedSelector copy paste pattern', () => { const state = store.getState() const currySelector = < State, Result, Params extends readonly any[], AdditionalFields >( selector: ((state: State, ...args: Params) => Result) & AdditionalFields ) => { const curriedSelector = (...args: Params) => { return (state: State) => { return selector(state, ...args) } } return Object.assign(curriedSelector, selector) } const createCurriedSelector = < InputSelectors extends SelectorArray, Result, OverrideMemoizeFunction extends UnknownMemoizer = typeof weakMapMemoize, OverrideArgsMemoizeFunction extends UnknownMemoizer = typeof weakMapMemoize >( ...args: Parameters< typeof createSelector< InputSelectors, Result, OverrideMemoizeFunction, OverrideArgsMemoizeFunction > > ) => { return currySelector(createSelector(...args)) } const selectTodoById = createSelector( [(state: RootState) => state.todos, (state: RootState, id: number) => id], (todos, id) => todos.find(todo => todo.id === id) ) const selectTodoByIdCurried = createCurriedSelector( [(state: RootState) => state.todos, (state: RootState, id: number) => id], (todos, id) => todos.find(todo => todo.id === id) ) expect(selectTodoById(state, 0)).toStrictEqual( selectTodoByIdCurried(0)(state) ) expect(selectTodoById.argsMemoize).toBe(selectTodoByIdCurried.argsMemoize) expect(selectTodoById.lastResult()).toBeDefined() expect(selectTodoByIdCurried.lastResult()).toBeDefined() expect(selectTodoById.lastResult()).toBe(selectTodoByIdCurried.lastResult()) expect(selectTodoById.memoize).toBe(selectTodoByIdCurried.memoize) expect(selectTodoById.memoizedResultFunc(state.todos, 0)).toBe( selectTodoByIdCurried.memoizedResultFunc(state.todos, 0) ) expect(selectTodoById.recomputations()).toBe( selectTodoByIdCurried.recomputations() ) expect(selectTodoById.resultFunc(state.todos, 0)).toBe( selectTodoByIdCurried.resultFunc(state.todos, 0) ) })