Add tests

src/EventEmitter.test.ts

@@ -0,0 +1,84 @@
+import { assert } from 'chai';
+import { EventEmitter } from './EventEmitter';
+
+describe('EventEmitter', () => {
+  let eventEmitter: EventEmitter;
+
+  beforeEach(() => {
+    eventEmitter = new EventEmitter();
+  });
+
+  describe('once', () => {
+    it('should trigger the listener only once', () => {
+      let count = 0;
+      const listener = () => count++;
+      eventEmitter.once('test', listener);
+      eventEmitter.emit('test');
+      assert.equal(count, 1);
+      eventEmitter.emit('test');
+      assert.equal(count, 1);
+    });
+  });
+
+  describe('emit', () => {
+    it('should emit events to listeners', () => {
+      let count1 = 0;
+      let count2 = 0;
+      const listener1 = () => count1++;
+      const listener2 = () => count2++;
+      eventEmitter.on('test', listener1);
+      eventEmitter.on('test', listener2);
+      eventEmitter.emit('test');
+      assert.equal(count1, 1);
+      assert.equal(count2, 1);
+      eventEmitter.emit('test');
+      assert.equal(count1, 2);
+      assert.equal(count2, 2);
+    });
+
+    it('should manage multiple listener types', () => {
+      let count1 = 0;
+      let count2 = 0;
+      const listener1 = () => count1++;
+      const listener2 = () => count2++;
+      eventEmitter.on('test', listener1);
+      eventEmitter.on('foo', listener2);
+      eventEmitter.emit('test');
+      assert.equal(count1, 1);
+      assert.equal(count2, 0);
+      eventEmitter.emit('foo');
+      assert.equal(count1, 1);
+      assert.equal(count2, 1);
+    });
+  });
+
+  describe('listeners', () => {
+    it('should return listeners for the type requested', () => {
+      assert.equal(eventEmitter.listeners('test').length, 0);
+      const listener = () => {};
+      eventEmitter.addListener('test', listener);
+      assert.deepEqual(eventEmitter.listeners('test'), [listener]);
+    });
+  });
+
+  describe('removeListener', () => {
+    it('should remove the specific listener', () => {
+      const listener1 = () => {};
+      const listener2 = () => {};
+      eventEmitter.addListener('foo', listener1);
+      eventEmitter.addListener('foo', listener2);
+      assert.equal(eventEmitter.listeners('foo').length, 2);
+      eventEmitter.removeListener('foo', listener1);
+      assert.deepEqual(eventEmitter.listeners('foo'), [listener2]);
+    });
+  });
+
+  describe('removeAllListeners', () => {
+    it('should clear all listeners', () => {
+      eventEmitter.addListener('foo', () => {});
+      assert.equal(eventEmitter.listeners('foo').length, 1);
+      eventEmitter.removeAllListeners('foo');
+      assert.equal(eventEmitter.listeners('foo').length, 0);
+    });
+  });
+});