util: Async event emitter tests

packages/util/test/asyncEventEmitter.spec.ts

@@ -1,7 +1,10 @@
+import { EventEmitter } from 'events'
 import { assert, describe, it } from 'vitest'
 
 import { AsyncEventEmitter } from '../src/index.js'
 
+import type { EventMap } from '../src/index.js'
+
 describe('async event emit/on test', async () => {
   it('should receive event', () => {
     const emitter = new AsyncEventEmitter()
@@ -29,3 +32,81 @@ describe('async event emit/once test', async () => {
     })
   })
 })
+
+describe('AsyncEventEmitter', () => {
+  it('should add listener using addListener()', () => {
+    const emitter = new AsyncEventEmitter<EventMap>()
+    const listener = () => {}
+    const event = 'event1'
+
+    emitter.addListener(event, listener)
+
+    assert.deepStrictEqual(emitter.listeners(event), [listener])
+  })
+
+  it('should prepend listener using prependListener()', () => {
+    const emitter = new AsyncEventEmitter<EventMap>()
+    const listener1 = () => {}
+    const listener2 = () => {}
+    const event = 'event1'
+
+    emitter.prependListener(event, listener1)
+    emitter.prependListener(event, listener2)
+
+    assert.deepStrictEqual(emitter.listeners(event), [listener2, listener1])
+  })
+
+  it('should prepend once listener using prependOnceListener()', () => {
+    const emitter = new AsyncEventEmitter<EventMap>()
+    const listener1 = () => {}
+    const listener2 = () => {}
+    const event = 'event1'
+
+    emitter.prependOnceListener(event, listener1)
+    emitter.prependOnceListener(event, listener2)
+
+    assert.deepStrictEqual(emitter.listeners(event), [listener2, listener1])
+  })
+
+  it('should return event names when using eventNames()', () => {
+    const emitter = new AsyncEventEmitter<EventMap>()
+    const event1 = 'event1'
+    const event2 = 'event2'
+
+    emitter.addListener(event1, () => {})
+    emitter.addListener(event2, () => {})
+
+    assert.deepStrictEqual(emitter.eventNames(), [event1, event2])
+  })
+
+  it('should return listeners for an event when using listeners()', () => {
+    const emitter = new AsyncEventEmitter<EventMap>()
+    const listener1 = () => {}
+    const listener2 = () => {}
+    const event = 'event1'
+
+    emitter.addListener(event, listener1)
+    emitter.addListener(event, listener2)
+
+    assert.deepStrictEqual(emitter.listeners(event), [listener1, listener2])
+  })
+
+  it('should return the maximum number of listeners when using getMaxListeners()', () => {
+    const emitter = new AsyncEventEmitter<EventMap>()
+
+    const maxListeners = emitter.getMaxListeners()
+
+    assert.strictEqual(maxListeners, EventEmitter.defaultMaxListeners)
+  })
+
+  it('should set the maximum number of listeners when using setMaxListeners()', () => {
+    const emitter = new AsyncEventEmitter<EventMap>()
+
+    const newMaxListeners = 10
+    emitter.setMaxListeners(newMaxListeners)
+
+    const maxListeners = emitter.getMaxListeners()
+
+    assert.strictEqual(maxListeners, newMaxListeners)
+  })
+})