core/packages/reactivity/__tests__/effect.spec.ts

import {
  ref,
  reactive,
  effect,
  stop,
  toRaw,
  TrackOpTypes,
  TriggerOpTypes,
  DebuggerEvent,
  markRaw,
  shallowReactive,
  readonly,
  ReactiveEffectRunner
} from '../src/index'
import { ITERATE_KEY } from '../src/effect'

describe('reactivity/effect', () => {
  it('should run the passed function once (wrapped by a effect)', () => {
    const fnSpy = vi.fn(() => {})
    effect(fnSpy)
    expect(fnSpy).toHaveBeenCalledTimes(1)
  })

  it('should observe basic properties', () => {
    let dummy
    const counter = reactive({ num: 0 })
    effect(() => (dummy = counter.num))

    expect(dummy).toBe(0)
    counter.num = 7
    expect(dummy).toBe(7)
  })

  it('should observe multiple properties', () => {
    let dummy
    const counter = reactive({ num1: 0, num2: 0 })
    effect(() => (dummy = counter.num1 + counter.num1 + counter.num2))

    expect(dummy).toBe(0)
    counter.num1 = counter.num2 = 7
    expect(dummy).toBe(21)
  })

  it('should handle multiple effects', () => {
    let dummy1, dummy2
    const counter = reactive({ num: 0 })
    effect(() => (dummy1 = counter.num))
    effect(() => (dummy2 = counter.num))

    expect(dummy1).toBe(0)
    expect(dummy2).toBe(0)
    counter.num++
    expect(dummy1).toBe(1)
    expect(dummy2).toBe(1)
  })

  it('should observe nested properties', () => {
    let dummy
    const counter = reactive({ nested: { num: 0 } })
    effect(() => (dummy = counter.nested.num))

    expect(dummy).toBe(0)
    counter.nested.num = 8
    expect(dummy).toBe(8)
  })

  it('should observe delete operations', () => {
    let dummy
    const obj = reactive<{
      prop?: string
    }>({ prop: 'value' })
    effect(() => (dummy = obj.prop))

    expect(dummy).toBe('value')
    delete obj.prop
    expect(dummy).toBe(undefined)
  })

  it('should observe has operations', () => {
    let dummy
    const obj = reactive<{ prop?: string | number }>({ prop: 'value' })
    effect(() => (dummy = 'prop' in obj))

    expect(dummy).toBe(true)
    delete obj.prop
    expect(dummy).toBe(false)
    obj.prop = 12
    expect(dummy).toBe(true)
  })

  it('should observe properties on the prototype chain', () => {
    let dummy
    const counter = reactive<{ num?: number }>({ num: 0 })
    const parentCounter = reactive({ num: 2 })
    Object.setPrototypeOf(counter, parentCounter)
    effect(() => (dummy = counter.num))

    expect(dummy).toBe(0)
    delete counter.num
    expect(dummy).toBe(2)
    parentCounter.num = 4
    expect(dummy).toBe(4)
    counter.num = 3
    expect(dummy).toBe(3)
  })

  it('should observe has operations on the prototype chain', () => {
    let dummy
    const counter = reactive<{ num?: number }>({ num: 0 })
    const parentCounter = reactive<{ num?: number }>({ num: 2 })
    Object.setPrototypeOf(counter, parentCounter)
    effect(() => (dummy = 'num' in counter))

    expect(dummy).toBe(true)
    delete counter.num
    expect(dummy).toBe(true)
    delete parentCounter.num
    expect(dummy).toBe(false)
    counter.num = 3
    expect(dummy).toBe(true)
  })

  it('should observe inherited property accessors', () => {
    let dummy, parentDummy, hiddenValue: any
    const obj = reactive<{ prop?: number }>({})
    const parent = reactive({
      set prop(value) {
        hiddenValue = value
      },
      get prop() {
        return hiddenValue
      }
    })
    Object.setPrototypeOf(obj, parent)
    effect(() => (dummy = obj.prop))
    effect(() => (parentDummy = parent.prop))

    expect(dummy).toBe(undefined)
    expect(parentDummy).toBe(undefined)
    obj.prop = 4
    expect(dummy).toBe(4)
    // this doesn't work, should it?
    // expect(parentDummy).toBe(4)
    parent.prop = 2
    expect(dummy).toBe(2)
    expect(parentDummy).toBe(2)
  })

  it('should observe function call chains', () => {
    let dummy
    const counter = reactive({ num: 0 })
    effect(() => (dummy = getNum()))

    function getNum() {
      return counter.num
    }

    expect(dummy).toBe(0)
    counter.num = 2
    expect(dummy).toBe(2)
  })

  it('should observe iteration', () => {
    let dummy
    const list = reactive(['Hello'])
    effect(() => (dummy = list.join(' ')))

    expect(dummy).toBe('Hello')
    list.push('World!')
    expect(dummy).toBe('Hello World!')
    list.shift()
    expect(dummy).toBe('World!')
  })

  it('should observe implicit array length changes', () => {
    let dummy
    const list = reactive(['Hello'])
    effect(() => (dummy = list.join(' ')))

    expect(dummy).toBe('Hello')
    list[1] = 'World!'
    expect(dummy).toBe('Hello World!')
    list[3] = 'Hello!'
    expect(dummy).toBe('Hello World!  Hello!')
  })

  it('should observe sparse array mutations', () => {
    let dummy
    const list = reactive<string[]>([])
    list[1] = 'World!'
    effect(() => (dummy = list.join(' ')))

    expect(dummy).toBe(' World!')
    list[0] = 'Hello'
    expect(dummy).toBe('Hello World!')
    list.pop()
    expect(dummy).toBe('Hello')
  })

  it('should observe enumeration', () => {
    let dummy = 0
    const numbers = reactive<Record<string, number>>({ num1: 3 })
    effect(() => {
      dummy = 0
      for (let key in numbers) {
        dummy += numbers[key]
      }
    })

    expect(dummy).toBe(3)
    numbers.num2 = 4
    expect(dummy).toBe(7)
    delete numbers.num1
    expect(dummy).toBe(4)
  })

  it('should observe symbol keyed properties', () => {
    const key = Symbol('symbol keyed prop')
    let dummy, hasDummy
    const obj = reactive<{ [key]?: string }>({ [key]: 'value' })
    effect(() => (dummy = obj[key]))
    effect(() => (hasDummy = key in obj))

    expect(dummy).toBe('value')
    expect(hasDummy).toBe(true)
    obj[key] = 'newValue'
    expect(dummy).toBe('newValue')
    delete obj[key]
    expect(dummy).toBe(undefined)
    expect(hasDummy).toBe(false)
  })

  it('should not observe well-known symbol keyed properties', () => {
    const key = Symbol.isConcatSpreadable
    let dummy
    const array: any = reactive([])
    effect(() => (dummy = array[key]))

    expect(array[key]).toBe(undefined)
    expect(dummy).toBe(undefined)
    array[key] = true
    expect(array[key]).toBe(true)
    expect(dummy).toBe(undefined)
  })

  it('should support manipulating an array while observing symbol keyed properties', () => {
    const key = Symbol()
    let dummy
    const array: any = reactive([1, 2, 3])
    effect(() => (dummy = array[key]))

    expect(dummy).toBe(undefined)
    array.pop()
    array.shift()
    array.splice(0, 1)
    expect(dummy).toBe(undefined)
    array[key] = 'value'
    array.length = 0
    expect(dummy).toBe('value')
  })

  it('should observe function valued properties', () => {
    const oldFunc = () => {}
    const newFunc = () => {}

    let dummy
    const obj = reactive({ func: oldFunc })
    effect(() => (dummy = obj.func))

    expect(dummy).toBe(oldFunc)
    obj.func = newFunc
    expect(dummy).toBe(newFunc)
  })

  it('should observe chained getters relying on this', () => {
    const obj = reactive({
      a: 1,
      get b() {
        return this.a
      }
    })

    let dummy
    effect(() => (dummy = obj.b))
    expect(dummy).toBe(1)
    obj.a++
    expect(dummy).toBe(2)
  })

  it('should observe methods relying on this', () => {
    const obj = reactive({
      a: 1,
      b() {
        return this.a
      }
    })

    let dummy
    effect(() => (dummy = obj.b()))
    expect(dummy).toBe(1)
    obj.a++
    expect(dummy).toBe(2)
  })

  it('should not observe set operations without a value change', () => {
    let hasDummy, getDummy
    const obj = reactive({ prop: 'value' })

    const getSpy = vi.fn(() => (getDummy = obj.prop))
    const hasSpy = vi.fn(() => (hasDummy = 'prop' in obj))
    effect(getSpy)
    effect(hasSpy)

    expect(getDummy).toBe('value')
    expect(hasDummy).toBe(true)
    obj.prop = 'value'
    expect(getSpy).toHaveBeenCalledTimes(1)
    expect(hasSpy).toHaveBeenCalledTimes(1)
    expect(getDummy).toBe('value')
    expect(hasDummy).toBe(true)
  })

  it('should not observe raw mutations', () => {
    let dummy
    const obj = reactive<{ prop?: string }>({})
    effect(() => (dummy = toRaw(obj).prop))

    expect(dummy).toBe(undefined)
    obj.prop = 'value'
    expect(dummy).toBe(undefined)
  })

  it('should not be triggered by raw mutations', () => {
    let dummy
    const obj = reactive<{ prop?: string }>({})
    effect(() => (dummy = obj.prop))

    expect(dummy).toBe(undefined)
    toRaw(obj).prop = 'value'
    expect(dummy).toBe(undefined)
  })

  it('should not be triggered by inherited raw setters', () => {
    let dummy, parentDummy, hiddenValue: any
    const obj = reactive<{ prop?: number }>({})
    const parent = reactive({
      set prop(value) {
        hiddenValue = value
      },
      get prop() {
        return hiddenValue
      }
    })
    Object.setPrototypeOf(obj, parent)
    effect(() => (dummy = obj.prop))
    effect(() => (parentDummy = parent.prop))

    expect(dummy).toBe(undefined)
    expect(parentDummy).toBe(undefined)
    toRaw(obj).prop = 4
    expect(dummy).toBe(undefined)
    expect(parentDummy).toBe(undefined)
  })

  it('should avoid implicit infinite recursive loops with itself', () => {
    const counter = reactive({ num: 0 })

    const counterSpy = vi.fn(() => counter.num++)
    effect(counterSpy)
    expect(counter.num).toBe(1)
    expect(counterSpy).toHaveBeenCalledTimes(1)
    counter.num = 4
    expect(counter.num).toBe(5)
    expect(counterSpy).toHaveBeenCalledTimes(2)
  })

  it('should avoid infinite recursive loops when use Array.prototype.push/unshift/pop/shift', () => {
    ;(['push', 'unshift'] as const).forEach(key => {
      const arr = reactive<number[]>([])
      const counterSpy1 = vi.fn(() => (arr[key] as any)(1))
      const counterSpy2 = vi.fn(() => (arr[key] as any)(2))
      effect(counterSpy1)
      effect(counterSpy2)
      expect(arr.length).toBe(2)
      expect(counterSpy1).toHaveBeenCalledTimes(1)
      expect(counterSpy2).toHaveBeenCalledTimes(1)
    })
    ;(['pop', 'shift'] as const).forEach(key => {
      const arr = reactive<number[]>([1, 2, 3, 4])
      const counterSpy1 = vi.fn(() => (arr[key] as any)())
      const counterSpy2 = vi.fn(() => (arr[key] as any)())
      effect(counterSpy1)
      effect(counterSpy2)
      expect(arr.length).toBe(2)
      expect(counterSpy1).toHaveBeenCalledTimes(1)
      expect(counterSpy2).toHaveBeenCalledTimes(1)
    })
  })

  it('should allow explicitly recursive raw function loops', () => {
    const counter = reactive({ num: 0 })
    const numSpy = vi.fn(() => {
      counter.num++
      if (counter.num < 10) {
        numSpy()
      }
    })
    effect(numSpy)
    expect(counter.num).toEqual(10)
    expect(numSpy).toHaveBeenCalledTimes(10)
  })

  it('should avoid infinite loops with other effects', () => {
    const nums = reactive({ num1: 0, num2: 1 })

    const spy1 = vi.fn(() => (nums.num1 = nums.num2))
    const spy2 = vi.fn(() => (nums.num2 = nums.num1))
    effect(spy1)
    effect(spy2)
    expect(nums.num1).toBe(1)
    expect(nums.num2).toBe(1)
    expect(spy1).toHaveBeenCalledTimes(1)
    expect(spy2).toHaveBeenCalledTimes(1)
    nums.num2 = 4
    expect(nums.num1).toBe(4)
    expect(nums.num2).toBe(4)
    expect(spy1).toHaveBeenCalledTimes(2)
    expect(spy2).toHaveBeenCalledTimes(2)
    nums.num1 = 10
    expect(nums.num1).toBe(10)
    expect(nums.num2).toBe(10)
    expect(spy1).toHaveBeenCalledTimes(3)
    expect(spy2).toHaveBeenCalledTimes(3)
  })

  it('should return a new reactive version of the function', () => {
    function greet() {
      return 'Hello World'
    }
    const effect1 = effect(greet)
    const effect2 = effect(greet)
    expect(typeof effect1).toBe('function')
    expect(typeof effect2).toBe('function')
    expect(effect1).not.toBe(greet)
    expect(effect1).not.toBe(effect2)
  })

  it('should discover new branches while running automatically', () => {
    let dummy
    const obj = reactive({ prop: 'value', run: false })

    const conditionalSpy = vi.fn(() => {
      dummy = obj.run ? obj.prop : 'other'
    })
    effect(conditionalSpy)

    expect(dummy).toBe('other')
    expect(conditionalSpy).toHaveBeenCalledTimes(1)
    obj.prop = 'Hi'
    expect(dummy).toBe('other')
    expect(conditionalSpy).toHaveBeenCalledTimes(1)
    obj.run = true
    expect(dummy).toBe('Hi')
    expect(conditionalSpy).toHaveBeenCalledTimes(2)
    obj.prop = 'World'
    expect(dummy).toBe('World')
    expect(conditionalSpy).toHaveBeenCalledTimes(3)
  })

  it('should discover new branches when running manually', () => {
    let dummy
    let run = false
    const obj = reactive({ prop: 'value' })
    const runner = effect(() => {
      dummy = run ? obj.prop : 'other'
    })

    expect(dummy).toBe('other')
    runner()
    expect(dummy).toBe('other')
    run = true
    runner()
    expect(dummy).toBe('value')
    obj.prop = 'World'
    expect(dummy).toBe('World')
  })

  it('should not be triggered by mutating a property, which is used in an inactive branch', () => {
    let dummy
    const obj = reactive({ prop: 'value', run: true })

    const conditionalSpy = vi.fn(() => {
      dummy = obj.run ? obj.prop : 'other'
    })
    effect(conditionalSpy)

    expect(dummy).toBe('value')
    expect(conditionalSpy).toHaveBeenCalledTimes(1)
    obj.run = false
    expect(dummy).toBe('other')
    expect(conditionalSpy).toHaveBeenCalledTimes(2)
    obj.prop = 'value2'
    expect(dummy).toBe('other')
    expect(conditionalSpy).toHaveBeenCalledTimes(2)
  })

  it('should handle deep effect recursion using cleanup fallback', () => {
    const results = reactive([0])
    const effects: { fx: ReactiveEffectRunner; index: number }[] = []
    for (let i = 1; i < 40; i++) {
      ;(index => {
        const fx = effect(() => {
          results[index] = results[index - 1] * 2
        })
        effects.push({ fx, index })
      })(i)
    }

    expect(results[39]).toBe(0)
    results[0] = 1
    expect(results[39]).toBe(Math.pow(2, 39))
  })

  it('should register deps independently during effect recursion', () => {
    const input = reactive({ a: 1, b: 2, c: 0 })
    const output = reactive({ fx1: 0, fx2: 0 })

    const fx1Spy = vi.fn(() => {
      let result = 0
      if (input.c < 2) result += input.a
      if (input.c > 1) result += input.b
      output.fx1 = result
    })

    const fx1 = effect(fx1Spy)

    const fx2Spy = vi.fn(() => {
      let result = 0
      if (input.c > 1) result += input.a
      if (input.c < 3) result += input.b
      output.fx2 = result + output.fx1
    })

    const fx2 = effect(fx2Spy)

    expect(fx1).not.toBeNull()
    expect(fx2).not.toBeNull()

    expect(output.fx1).toBe(1)
    expect(output.fx2).toBe(2 + 1)
    expect(fx1Spy).toHaveBeenCalledTimes(1)
    expect(fx2Spy).toHaveBeenCalledTimes(1)

    fx1Spy.mockClear()
    fx2Spy.mockClear()
    input.b = 3
    expect(output.fx1).toBe(1)
    expect(output.fx2).toBe(3 + 1)
    expect(fx1Spy).toHaveBeenCalledTimes(0)
    expect(fx2Spy).toHaveBeenCalledTimes(1)

    fx1Spy.mockClear()
    fx2Spy.mockClear()
    input.c = 1
    expect(output.fx1).toBe(1)
    expect(output.fx2).toBe(3 + 1)
    expect(fx1Spy).toHaveBeenCalledTimes(1)
    expect(fx2Spy).toHaveBeenCalledTimes(1)

    fx1Spy.mockClear()
    fx2Spy.mockClear()
    input.c = 2
    expect(output.fx1).toBe(3)
    expect(output.fx2).toBe(1 + 3 + 3)
    expect(fx1Spy).toHaveBeenCalledTimes(1)

    // Invoked twice due to change of fx1.
    expect(fx2Spy).toHaveBeenCalledTimes(2)

    fx1Spy.mockClear()
    fx2Spy.mockClear()
    input.c = 3
    expect(output.fx1).toBe(3)
    expect(output.fx2).toBe(1 + 3)
    expect(fx1Spy).toHaveBeenCalledTimes(1)
    expect(fx2Spy).toHaveBeenCalledTimes(1)

    fx1Spy.mockClear()
    fx2Spy.mockClear()
    input.a = 10
    expect(output.fx1).toBe(3)
    expect(output.fx2).toBe(10 + 3)
    expect(fx1Spy).toHaveBeenCalledTimes(0)
    expect(fx2Spy).toHaveBeenCalledTimes(1)
  })

  it('should not double wrap if the passed function is a effect', () => {
    const runner = effect(() => {})
    const otherRunner = effect(runner)
    expect(runner).not.toBe(otherRunner)
    expect(runner.effect.fn).toBe(otherRunner.effect.fn)
  })

  it('should wrap if the passed function is a fake effect', () => {
    const fakeRunner = () => {}
    fakeRunner.effect = {}
    const runner = effect(fakeRunner)
    expect(fakeRunner).not.toBe(runner)
    expect(runner.effect.fn).toBe(fakeRunner)
  })

  it('should not run multiple times for a single mutation', () => {
    let dummy
    const obj = reactive<Record<string, number>>({})
    const fnSpy = vi.fn(() => {
      for (const key in obj) {
        dummy = obj[key]
      }
      dummy = obj.prop
    })
    effect(fnSpy)

    expect(fnSpy).toHaveBeenCalledTimes(1)
    obj.prop = 16
    expect(dummy).toBe(16)
    expect(fnSpy).toHaveBeenCalledTimes(2)
  })

  it('should allow nested effects', () => {
    const nums = reactive({ num1: 0, num2: 1, num3: 2 })
    const dummy: any = {}

    const childSpy = vi.fn(() => (dummy.num1 = nums.num1))
    const childeffect = effect(childSpy)
    const parentSpy = vi.fn(() => {
      dummy.num2 = nums.num2
      childeffect()
      dummy.num3 = nums.num3
    })
    effect(parentSpy)

    expect(dummy).toEqual({ num1: 0, num2: 1, num3: 2 })
    expect(parentSpy).toHaveBeenCalledTimes(1)
    expect(childSpy).toHaveBeenCalledTimes(2)
    // this should only call the childeffect
    nums.num1 = 4
    expect(dummy).toEqual({ num1: 4, num2: 1, num3: 2 })
    expect(parentSpy).toHaveBeenCalledTimes(1)
    expect(childSpy).toHaveBeenCalledTimes(3)
    // this calls the parenteffect, which calls the childeffect once
    nums.num2 = 10
    expect(dummy).toEqual({ num1: 4, num2: 10, num3: 2 })
    expect(parentSpy).toHaveBeenCalledTimes(2)
    expect(childSpy).toHaveBeenCalledTimes(4)
    // this calls the parenteffect, which calls the childeffect once
    nums.num3 = 7
    expect(dummy).toEqual({ num1: 4, num2: 10, num3: 7 })
    expect(parentSpy).toHaveBeenCalledTimes(3)
    expect(childSpy).toHaveBeenCalledTimes(5)
  })

  it('should observe json methods', () => {
    let dummy = <Record<string, number>>{}
    const obj = reactive<Record<string, number>>({})
    effect(() => {
      dummy = JSON.parse(JSON.stringify(obj))
    })
    obj.a = 1
    expect(dummy.a).toBe(1)
  })

  it('should observe class method invocations', () => {
    class Model {
      count: number
      constructor() {
        this.count = 0
      }
      inc() {
        this.count++
      }
    }
    const model = reactive(new Model())
    let dummy
    effect(() => {
      dummy = model.count
    })
    expect(dummy).toBe(0)
    model.inc()
    expect(dummy).toBe(1)
  })

  it('lazy', () => {
    const obj = reactive({ foo: 1 })
    let dummy
    const runner = effect(() => (dummy = obj.foo), { lazy: true })
    expect(dummy).toBe(undefined)

    expect(runner()).toBe(1)
    expect(dummy).toBe(1)
    obj.foo = 2
    expect(dummy).toBe(2)
  })

  it('scheduler', () => {
    let dummy
    let run: any
    const scheduler = vi.fn(() => {
      run = runner
    })
    const obj = reactive({ foo: 1 })
    const runner = effect(
      () => {
        dummy = obj.foo
      },
      { scheduler }
    )
    expect(scheduler).not.toHaveBeenCalled()
    expect(dummy).toBe(1)
    // should be called on first trigger
    obj.foo++
    expect(scheduler).toHaveBeenCalledTimes(1)
    // should not run yet
    expect(dummy).toBe(1)
    // manually run
    run()
    // should have run
    expect(dummy).toBe(2)
  })

  it('events: onTrack', () => {
    let events: DebuggerEvent[] = []
    let dummy
    const onTrack = vi.fn((e: DebuggerEvent) => {
      events.push(e)
    })
    const obj = reactive({ foo: 1, bar: 2 })
    const runner = effect(
      () => {
        dummy = obj.foo
        dummy = 'bar' in obj
        dummy = Object.keys(obj)
      },
      { onTrack }
    )
    expect(dummy).toEqual(['foo', 'bar'])
    expect(onTrack).toHaveBeenCalledTimes(3)
    expect(events).toEqual([
      {
        effect: runner.effect,
        target: toRaw(obj),
        type: TrackOpTypes.GET,
        key: 'foo'
      },
      {
        effect: runner.effect,
        target: toRaw(obj),
        type: TrackOpTypes.HAS,
        key: 'bar'
      },
      {
        effect: runner.effect,
        target: toRaw(obj),
        type: TrackOpTypes.ITERATE,
        key: ITERATE_KEY
      }
    ])
  })

  it('events: onTrigger', () => {
    let events: DebuggerEvent[] = []
    let dummy
    const onTrigger = vi.fn((e: DebuggerEvent) => {
      events.push(e)
    })
    const obj = reactive<{ foo?: number }>({ foo: 1 })
    const runner = effect(
      () => {
        dummy = obj.foo
      },
      { onTrigger }
    )

    obj.foo!++
    expect(dummy).toBe(2)
    expect(onTrigger).toHaveBeenCalledTimes(1)
    expect(events[0]).toEqual({
      effect: runner.effect,
      target: toRaw(obj),
      type: TriggerOpTypes.SET,
      key: 'foo',
      oldValue: 1,
      newValue: 2
    })

    delete obj.foo
    expect(dummy).toBeUndefined()
    expect(onTrigger).toHaveBeenCalledTimes(2)
    expect(events[1]).toEqual({
      effect: runner.effect,
      target: toRaw(obj),
      type: TriggerOpTypes.DELETE,
      key: 'foo',
      oldValue: 2
    })
  })

  it('stop', () => {
    let dummy
    const obj = reactive({ prop: 1 })
    const runner = effect(() => {
      dummy = obj.prop
    })
    obj.prop = 2
    expect(dummy).toBe(2)
    stop(runner)
    obj.prop = 3
    expect(dummy).toBe(2)

    // stopped effect should still be manually callable
    runner()
    expect(dummy).toBe(3)
  })

  // #5707
  // when an effect completes its run, it should clear the tracking bits of
  // its tracked deps. However, if the effect stops itself, the deps list is
  // emptied so their bits are never cleared.
  it('edge case: self-stopping effect tracking ref', () => {
    const c = ref(true)
    const runner = effect(() => {
      // reference ref
      if (!c.value) {
        // stop itself while running
        stop(runner)
      }
    })
    // trigger run
    c.value = !c.value
    // should clear bits
    expect((c as any).dep.w).toBe(0)
    expect((c as any).dep.n).toBe(0)
  })

  it('events: onStop', () => {
    const onStop = vi.fn()
    const runner = effect(() => {}, {
      onStop
    })

    stop(runner)
    expect(onStop).toHaveBeenCalled()
  })

  it('stop: a stopped effect is nested in a normal effect', () => {
    let dummy
    const obj = reactive({ prop: 1 })
    const runner = effect(() => {
      dummy = obj.prop
    })
    stop(runner)
    obj.prop = 2
    expect(dummy).toBe(1)

    // observed value in inner stopped effect
    // will track outer effect as an dependency
    effect(() => {
      runner()
    })
    expect(dummy).toBe(2)

    // notify outer effect to run
    obj.prop = 3
    expect(dummy).toBe(3)
  })

  it('markRaw', () => {
    const obj = reactive({
      foo: markRaw({
        prop: 0
      })
    })
    let dummy
    effect(() => {
      dummy = obj.foo.prop
    })
    expect(dummy).toBe(0)
    obj.foo.prop++
    expect(dummy).toBe(0)
    obj.foo = { prop: 1 }
    expect(dummy).toBe(1)
  })

  it('should not be triggered when the value and the old value both are NaN', () => {
    const obj = reactive({
      foo: NaN
    })
    const fnSpy = vi.fn(() => obj.foo)
    effect(fnSpy)
    obj.foo = NaN
    expect(fnSpy).toHaveBeenCalledTimes(1)
  })

  it('should trigger all effects when array length is set to 0', () => {
    const observed: any = reactive([1])
    let dummy, record
    effect(() => {
      dummy = observed.length
    })
    effect(() => {
      record = observed[0]
    })
    expect(dummy).toBe(1)
    expect(record).toBe(1)

    observed[1] = 2
    expect(observed[1]).toBe(2)

    observed.unshift(3)
    expect(dummy).toBe(3)
    expect(record).toBe(3)

    observed.length = 0
    expect(dummy).toBe(0)
    expect(record).toBeUndefined()
  })

  it('should not be triggered when set with the same proxy', () => {
    const obj = reactive({ foo: 1 })
    const observed: any = reactive({ obj })
    const fnSpy = vi.fn(() => observed.obj)

    effect(fnSpy)

    expect(fnSpy).toHaveBeenCalledTimes(1)
    observed.obj = obj
    expect(fnSpy).toHaveBeenCalledTimes(1)

    const obj2 = reactive({ foo: 1 })
    const observed2: any = shallowReactive({ obj2 })
    const fnSpy2 = vi.fn(() => observed2.obj2)

    effect(fnSpy2)

    expect(fnSpy2).toHaveBeenCalledTimes(1)
    observed2.obj2 = obj2
    expect(fnSpy2).toHaveBeenCalledTimes(1)
  })

  it('should be triggered when set length with string', () => {
    let ret1 = 'idle'
    let ret2 = 'idle'
    const arr1 = reactive(new Array(11).fill(0))
    const arr2 = reactive(new Array(11).fill(0))
    effect(() => {
      ret1 = arr1[10] === undefined ? 'arr[10] is set to empty' : 'idle'
    })
    effect(() => {
      ret2 = arr2[10] === undefined ? 'arr[10] is set to empty' : 'idle'
    })
    arr1.length = 2
    arr2.length = '2' as any
    expect(ret1).toBe(ret2)
  })

  describe('readonly + reactive for Map', () => {
    test('should work with readonly(reactive(Map))', () => {
      const m = reactive(new Map())
      const roM = readonly(m)
      const fnSpy = vi.fn(() => roM.get(1))

      effect(fnSpy)
      expect(fnSpy).toHaveBeenCalledTimes(1)
      m.set(1, 1)
      expect(fnSpy).toHaveBeenCalledTimes(2)
    })

    test('should work with observed value as key', () => {
      const key = reactive({})
      const m = reactive(new Map())
      m.set(key, 1)
      const roM = readonly(m)
      const fnSpy = vi.fn(() => roM.get(key))

      effect(fnSpy)
      expect(fnSpy).toHaveBeenCalledTimes(1)
      m.set(key, 1)
      expect(fnSpy).toHaveBeenCalledTimes(1)
      m.set(key, 2)
      expect(fnSpy).toHaveBeenCalledTimes(2)
    })

    test('should track hasOwnProperty', () => {
      const obj: any = reactive({})
      let has = false
      const fnSpy = vi.fn()

      effect(() => {
        fnSpy()
        has = obj.hasOwnProperty('foo')
      })
      expect(fnSpy).toHaveBeenCalledTimes(1)
      expect(has).toBe(false)

      obj.foo = 1
      expect(fnSpy).toHaveBeenCalledTimes(2)
      expect(has).toBe(true)

      delete obj.foo
      expect(fnSpy).toHaveBeenCalledTimes(3)
      expect(has).toBe(false)

      // should not trigger on unrelated key
      obj.bar = 2
      expect(fnSpy).toHaveBeenCalledTimes(3)
      expect(has).toBe(false)
    })
  })
})