test(index): add tests

add tests

src/index.ts

@@ -5,7 +5,7 @@ export type Subscriptions = Map<
 >;
 export type Unsubscribe = { unsubscribe: () => void };
 
-export class EventEmitter {
+export default class EventEmitter {
   subscriptions: Subscriptions;
 
   constructor() {
@@ -41,7 +41,7 @@ export class EventEmitter {
    * @param {string} eventName
    * @param {Array<any>} args
    */
-  emit(eventName: string, args: Array<any> = []): void {
+  emit(eventName: string, ...args: Array<any>): void {
     (this.subscriptions.get(eventName) || []).forEach(({ callback }) =>
       callback(...args)
     );

test/index.spec.ts

@@ -1,13 +1,85 @@
-import { myPackage } from '../src';
+import EventEmitter from '../src';
 
-describe('index', () => {
-  describe('myPackage', () => {
-    it('should return a string containing the message', () => {
-      const message = 'Hello';
+describe('eventEmitter', () => {
+  it('should add callback to subscriptions if it has no subscriptions', () => {
+    const testCallbackA = jest.fn();
 
-      const result = myPackage(message);
+    const eventEmitter = new EventEmitter();
+    eventEmitter.subscribe('test-event', testCallbackA);
 
-      expect(result).toMatch(message);
+    expect(eventEmitter.subscriptions.has('test-event')).toEqual(true);
+    expect(eventEmitter.subscriptions.get('test-event')).toEqual([
+      { id: expect.any(Symbol), callback: testCallbackA },
+    ]);
+  });
+
+  it('should add callback to subscriptions if it has subscriptions', () => {
+    const testCallbackA = jest.fn();
+    const testCallbackB = jest.fn();
+
+    const eventEmitter = new EventEmitter();
+    eventEmitter.subscribe('test-event', testCallbackA);
+    eventEmitter.subscribe('test-event', testCallbackB);
+
+    expect(eventEmitter.subscriptions.has('test-event')).toEqual(true);
+    expect(eventEmitter.subscriptions.get('test-event')).toContainEqual({
+      id: expect.any(Symbol),
+      callback: testCallbackA,
+    });
+  });
+
+  it('should add callback for another event to subscriptions', () => {
+    const testCallbackA = jest.fn();
+    const testCallbackB = jest.fn();
+
+    const eventEmitter = new EventEmitter();
+    eventEmitter.subscribe('test-event-a', testCallbackA);
+    eventEmitter.subscribe('test-event-b', testCallbackB);
+
+    expect(eventEmitter.subscriptions.has('test-event-a')).toEqual(true);
+    expect(eventEmitter.subscriptions.get('test-event-a')).toContainEqual({
+      id: expect.any(Symbol),
+      callback: testCallbackA,
     });
+    expect(eventEmitter.subscriptions.has('test-event-b')).toEqual(true);
+    expect(eventEmitter.subscriptions.get('test-event-b')).toContainEqual({
+      id: expect.any(Symbol),
+      callback: testCallbackB,
+    });
+  });
+
+  it('should call all subscriptions', () => {
+    const testCallbackA = jest.fn();
+    const testCallbackB = jest.fn();
+    const mockEventArgs = { a: 'a' };
+
+    const eventEmitter = new EventEmitter();
+    eventEmitter.subscribe('test-event', testCallbackA);
+    eventEmitter.subscribe('test-event', testCallbackB);
+    eventEmitter.emit('test-event', mockEventArgs);
+
+    expect(testCallbackA).toHaveBeenCalled();
+    expect(testCallbackA).toHaveBeenCalledWith(mockEventArgs);
+    expect(testCallbackB).toHaveBeenCalled();
+    expect(testCallbackB).toHaveBeenCalledWith(mockEventArgs);
+  });
+
+  it('should not call unsubscribed callbacks', () => {
+    const testCallbackA = jest.fn();
+    const testCallbackB = jest.fn();
+    const mockEventArgs = { a: 'a' };
+
+    const eventEmitter = new EventEmitter();
+    const { unsubscribe: unsubscribeCallbackA } = eventEmitter.subscribe(
+      'test-event',
+      testCallbackA
+    );
+    eventEmitter.subscribe('test-event', testCallbackB);
+    unsubscribeCallbackA();
+    eventEmitter.emit('test-event', mockEventArgs);
+
+    expect(testCallbackA).not.toHaveBeenCalled();
+    expect(testCallbackB).toHaveBeenCalled();
+    expect(testCallbackB).toHaveBeenCalledWith(mockEventArgs);
   });
 });