import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
import debounce from './debounce'

describe('debounce', () => {
    let func: () => void

    beforeEach(() => {
        vi.useFakeTimers()
        func = vi.fn()
    })

    afterEach(() => {
        vi.useRealTimers()
    })

    it('is not called immediately', () => {
        const debouncedFunc = debounce(func, 1000)
        debouncedFunc()
        expect(func).toHaveBeenCalledTimes(0)
    })

    it('is not called upon several rapid calls', () => {
        const debouncedFunc = debounce(func, 1000)
        for (let i = 0; i < 10; i++) {
            vi.advanceTimersByTime(500)
            debouncedFunc()
        }
        expect(func).toHaveBeenCalledTimes(0)
    })

    it('is called after debounce time', () => {
        const debouncedFunc = debounce(func, 1000)
        debouncedFunc()
        vi.advanceTimersByTime(1000)
        expect(func).toHaveBeenCalledTimes(1)
    })

    it('is called immediately if immediate is true', () => {
        const debouncedFunc = debounce(func, 1000, true)
        debouncedFunc()
        expect(func).toHaveBeenCalledTimes(1)
    })

    it('is called once upon several rapid calls if immediate is true', () => {
        const debouncedFunc = debounce(func, 1000, true)
        for (let i = 0; i < 10; i++) {
            vi.advanceTimersByTime(500)
            debouncedFunc()
        }
        expect(func).toHaveBeenCalledTimes(1)
    })
})