Eventful.test.ts

import {Eventful} from './Eventful.js'

// TODO move type def to @lume/cli, map @types/jest's `expect` type into the
// global env.
declare global {
	function expect(...args: any[]): any
}

let eventCount = 0
let eventCount2 = 0

describe('Eventful', () => {
	describe('provides an event pattern', () => {
		it('triggers an event handler based on event names', () => {
			const MyClass = Eventful()
			const o = new MyClass()

			const eventHandler = () => {
				eventCount += 1
			}

			const eventHandler2 = () => {
				eventCount2 += 1
			}

			o.on('foo', eventHandler)
			o.on('bar', eventHandler2)

			o.emit('foo')

			expect(eventCount).toBe(1)
			expect(eventCount2).toBe(0)

			o.emit('foo')

			expect(eventCount).toBe(2)
			expect(eventCount2).toBe(0)

			o.emit('foo')

			expect(eventCount).toBe(3)
			expect(eventCount2).toBe(0)

			o.emit('foo')
			o.emit('foo')
			o.emit('foo')

			expect(eventCount).toBe(6)
			expect(eventCount2).toBe(0)

			o.emit('bar')

			expect(eventCount).toBe(6)
			expect(eventCount2).toBe(1)

			o.emit('bar')

			expect(eventCount).toBe(6)
			expect(eventCount2).toBe(2)

			o.emit('bar')

			expect(eventCount).toBe(6)
			expect(eventCount2).toBe(3)

			o.off('foo', eventHandler)

			o.emit('foo')
			o.emit('foo')
			o.emit('foo')

			expect(eventCount).toBe(6)
			expect(eventCount2).toBe(3)

			o.emit('bar')
			o.emit('bar')
			o.emit('bar')

			expect(eventCount).toBe(6)
			expect(eventCount2).toBe(6)

			o.off('bar', eventHandler)

			o.emit('bar')
			o.emit('bar')
			o.emit('bar')

			expect(eventCount).toBe(6)
			expect(eventCount2).toBe(9)

			o.off('bar', eventHandler2)

			o.emit('bar')
			o.emit('bar')
			o.emit('bar')

			expect(eventCount).toBe(6)
			expect(eventCount2).toBe(9)
		})

		it('passes event payloads to event handlers', () => {
			class MyClass extends Eventful() {}
			const o = new MyClass()

			let thePayload: string | number | undefined
			let thePayload2: number | undefined

			const handler = (payload: any) => {
				thePayload = payload
			}

			const handler2 = (payload: any) => {
				thePayload2 = payload
			}

			o.on('foo', handler)
			o.on('bar', handler2)

			o.emit('foo', 56)

			expect(thePayload).toBe(56)
			expect(thePayload2).toBe(undefined)

			o.emit('bar', 42)

			expect(thePayload).toBe(56)
			expect(thePayload2).toBe(42)

			o.off('bar', handler2)

			o.emit('foo', 'oh yeah')
			o.emit('bar', 123)

			expect(thePayload).toBe('oh yeah')
			expect(thePayload2).toBe(42)
		})

		it('allows callbacks to be paired with contexts with which to be called', () => {
			class MyClass extends Eventful() {}
			const o = new MyClass()

			let obj = {n: 0}
			const o1 = {}
			const o2 = {}

			const callback = function (this: any, data: {n: number}) {
				// the first two calls
				if (data.n <= 1) {
					if (data.n === 0) {
						data.n++
						expect(this).toBe(o1)
					} else {
						data.n++
						expect(this).toBe(o2)
					}
				}

				// the 3rd and 4th calls
				else {
					data.n++
					expect(this).toBe(o2)
				}
			}

			o.on('foo', callback, o1)
			o.on('foo', callback, o2)

			o.emit('foo', obj)

			expect(obj.n).toBe(2)

			o.off('foo', callback, o1)

			o.emit('foo', obj)
			o.emit('foo', obj)

			expect(obj.n).toBe(4)

			o.off('foo', callback, o2)

			o.emit('foo', obj)
			o.emit('foo', obj)
			o.emit('foo', obj)

			expect(obj.n).toBe(4)
		})

		it('allows us to check objects are instances of the mixin class or composed classes', () => {
			const MyClass = Eventful()
			class OtherClass extends Eventful() {}
			class AnotherClass extends Eventful(Array) {}

			let o = new MyClass()
			expect(o).toBeInstanceOf(Eventful)
			expect(o).toBeInstanceOf(MyClass)
			expect(o).not.toBeInstanceOf(OtherClass)
			expect(o).not.toBeInstanceOf(AnotherClass)
			expect(o).not.toBeInstanceOf(Array)

			o = new OtherClass()
			expect(o).toBeInstanceOf(Eventful)
			expect(o).not.toBeInstanceOf(MyClass)
			expect(o).toBeInstanceOf(OtherClass)
			expect(o).not.toBeInstanceOf(AnotherClass)
			expect(o).not.toBeInstanceOf(Array)

			o = new AnotherClass()
			expect(o).toBeInstanceOf(Eventful)
			expect(o).not.toBeInstanceOf(MyClass)
			expect(o).not.toBeInstanceOf(OtherClass)
			expect(o).toBeInstanceOf(AnotherClass)
			expect(o).toBeInstanceOf(Array)
		})
	})
})