first commmit

tests/common/EventBus.test.ts

@@ -0,0 +1,98 @@
+import { EventBus } from '@common/EventBus';
+
+describe('EventBus', () => {
+    let bus: EventBus;
+
+    beforeEach(() => {
+        bus = new EventBus();
+    });
+
+    it('delivers emitted payload to on() subscribers', () => {
+        const spy = jest.fn();
+        bus.on<number>('hit', spy);
+        bus.emit('hit', 42);
+        expect(spy).toHaveBeenCalledWith(42);
+    });
+
+    it('ignores duplicate subscriptions of the same handler', () => {
+        const spy = jest.fn();
+        bus.on('hit', spy);
+        bus.on('hit', spy);
+        bus.emit('hit', 1);
+        expect(spy).toHaveBeenCalledTimes(1);
+        expect(bus.listenerCount('hit')).toBe(1);
+    });
+
+    it('fires once() handlers exactly one time', () => {
+        const spy = jest.fn();
+        bus.once('hit', spy);
+        bus.emit('hit', 1);
+        bus.emit('hit', 2);
+        expect(spy).toHaveBeenCalledTimes(1);
+        expect(bus.listenerCount('hit')).toBe(0);
+    });
+
+    it('off(event, fn) removes only that handler', () => {
+        const a = jest.fn();
+        const b = jest.fn();
+        bus.on('hit', a);
+        bus.on('hit', b);
+        bus.off('hit', a);
+        bus.emit('hit', 1);
+        expect(a).not.toHaveBeenCalled();
+        expect(b).toHaveBeenCalledTimes(1);
+    });
+
+    it('off(event) clears all handlers of that event', () => {
+        const a = jest.fn();
+        const b = jest.fn();
+        bus.on('hit', a);
+        bus.on('hit', b);
+        bus.off('hit');
+        bus.emit('hit', 1);
+        expect(a).not.toHaveBeenCalled();
+        expect(b).not.toHaveBeenCalled();
+        expect(bus.listenerCount('hit')).toBe(0);
+    });
+
+    it('isolates exceptions — one bad listener does not break fan-out', () => {
+        const err = jest.fn();
+        bus.setErrorHook(err);
+        const good = jest.fn();
+        bus.on('hit', () => {
+            throw new Error('boom');
+        });
+        bus.on('hit', good);
+        bus.emit('hit', 1);
+        expect(good).toHaveBeenCalledTimes(1);
+        expect(err).toHaveBeenCalledTimes(1);
+        expect(err.mock.calls[0][0]).toBe('hit');
+    });
+
+    it('emit on an unknown event is a no-op', () => {
+        expect(() => bus.emit('ghost', 1)).not.toThrow();
+    });
+
+    it('clear() drops every handler of every event', () => {
+        bus.on('a', () => {});
+        bus.on('b', () => {});
+        bus.clear();
+        expect(bus.listenerCount('a')).toBe(0);
+        expect(bus.listenerCount('b')).toBe(0);
+    });
+
+    it('supports off for a non-existent handler without error', () => {
+        const spy = jest.fn();
+        bus.off('hit', spy);
+        expect(bus.listenerCount('hit')).toBe(0);
+    });
+
+    it('handles a once-handler unsubscribing itself during emit', () => {
+        const calls: number[] = [];
+        bus.once<number>('tick', (n) => calls.push(n));
+        bus.on<number>('tick', (n) => calls.push(n * 10));
+        bus.emit('tick', 1);
+        bus.emit('tick', 2);
+        expect(calls).toEqual([1, 10, 20]);
+    });
+});