add tests

src/rooms/gateways/rooms.gateway.spec.ts

@@ -1,8 +1,10 @@
 import { Test, TestingModule } from '@nestjs/testing';
 import { RoomsGateway } from './rooms.gateway';
+import { Socket } from 'socket.io';
 
 describe('RoomsGateway', () => {
   let gateway: RoomsGateway;
+  let socket: jest.Mocked<Socket>;
 
   beforeEach(async () => {
     const module: TestingModule = await Test.createTestingModule({
@@ -12,7 +14,33 @@ describe('RoomsGateway', () => {
     gateway = module.get<RoomsGateway>(RoomsGateway);
   });
 
+  beforeEach(() => {
+    socket = {
+      rooms: new Set(),
+      join: jest.fn().mockImplementation((room) => socket.rooms.add(room)),
+      leave: jest.fn().mockImplementation((room) => socket.rooms.delete(room)),
+    } as unknown as jest.Mocked<Socket>;
+  });
+
   it('should be defined', () => {
     expect(gateway).toBeDefined();
   });
+
+  describe('#join()', () => {
+    it('should join', () => {
+      const ret = gateway.join(socket, 'FAKE_ROOM');
+      expect(ret).toEqual(['FAKE_ROOM']);
+    });
+  });
+
+  describe('#leave()', () => {
+    beforeEach(() => {
+      socket.rooms.add('FAKE_ROOM');
+    });
+
+    it('should leave', () => {
+      const ret = gateway.leave(socket, 'FAKE_ROOM');
+      expect(ret).toEqual([]);
+    });
+  });
 });