import type { Emitter } from '.'
import { createEmitter } from '.'

describe('event emitter', () => {
    let events: Emitter

    beforeEach(() => {
        events = createEmitter()
    })

    it('should allow subscribing to named events', () => {
        const callback = jest.fn()
        events.on('onSelectionChange', callback)
        events.emit('onSelectionChange', new Set(['1', '2']))
        expect(callback).toHaveBeenCalledWith(new Set(['1', '2']))
    })

    it('should allow unsubscribing', () => {
        const callback = jest.fn()
        const unsubscribe = events.on('onSelectionChange', callback)
        unsubscribe()
        events.emit('onSelectionChange', new Set(['1', '2']))
        expect(callback).not.toHaveBeenCalled()
    })

    it('should only remove the unsubscribed listener, not other listeners', () => {
        const callbackA = jest.fn()
        const callbackB = jest.fn()
        events.on('onSelectionChange', callbackA)
        const unsubscribeB = events.on('onSelectionChange', callbackB)

        unsubscribeB()

        events.emit('onSelectionChange', new Set(['1']))
        expect(callbackA).toHaveBeenCalledWith(new Set(['1']))
        expect(callbackB).not.toHaveBeenCalled()
    })
})