/
memoize.spec.js
99 lines (83 loc) · 1.81 KB
/
memoize.spec.js
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import {memoize} from './memoize'
test('memoize function without input arguments', () => {
const fn = () => 4
const memoized = memoize(fn)
expect(typeof memoized()).toBe('function')
})
test('happy', () => {
let counter = 0
const fn = ({a, b, c}) => {
counter++
return a + b - c
}
const memoized = memoize(fn)
expect(
memoized({
a: 1,
c: 3,
b: 2,
})
).toBe(0)
expect(counter).toBe(1)
expect(
memoized({
c: 3,
a: 1,
b: 2,
})
).toBe(0)
expect(counter).toBe(1)
})
test('normal function', () => {
let counter = 0
const fn = (a, b) => {
counter++
return a + b
}
const memoized = memoize(fn)
expect(memoized(1, 2)).toBe(3)
expect(memoized(1, 2)).toBe(3)
expect(memoized(1, 2)).toBe(3)
expect(counter).toBe(1)
expect(memoized(2, 2)).toBe(4)
expect(counter).toBe(2)
expect(memoized(1, 2)).toBe(3)
expect(counter).toBe(2)
})
test('async function', async () => {
let counter = 0
const delay = ms =>
new Promise(resolve => {
setTimeout(resolve, ms)
})
const fn = async (ms, a, b) => {
await delay(ms)
counter++
return a + b
}
const memoized = memoize(fn)
expect(await memoized(100, 1, 2)).toBe(3)
expect(await memoized(100, 1, 2)).toBe(3)
expect(await memoized(100, 1, 2)).toBe(3)
expect(counter).toBe(1)
expect(await memoized(100, 2, 2)).toBe(4)
expect(counter).toBe(2)
expect(await memoized(100, 1, 2)).toBe(3)
expect(counter).toBe(2)
})
test('string as argument', () => {
let count = 0
const foo = 'foo'
const tester = memoize(n => {
count++
return `${n}bar`
})
tester(foo)
tester(foo)
tester(foo)
expect(tester(foo)).toEqual('foobar')
expect(count).toEqual(1)
tester('baz')
expect(tester('baz')).toEqual('bazbar')
expect(count).toEqual(2)
})