style(eslint): 🎨명시적인 null check, 강화된 eslint

server/.eslintrc.js

@@ -21,5 +21,7 @@ module.exports = {
     '@typescript-eslint/explicit-function-return-type': 'off',
     '@typescript-eslint/explicit-module-boundary-types': 'off',
     '@typescript-eslint/no-explicit-any': 'off',
+    eqeqeq: ['error', 'always'],
+    'no-implicit-coercion': ['error', { allow: ['!!'] }],
   },
 };

server/src/app.controller.ts

@@ -12,6 +12,7 @@ import { SessionAuthGuard } from './auth/auth.guard';
 import User from './entities/user.entity';
 import { RoomService } from './room/room.service';
 import { isUserSession, UserSession } from './types/userSession';
+import { isNil } from '@nestjs/common/utils/shared.utils';
 
 @UseGuards(SessionAuthGuard)
 @Controller()
@@ -32,7 +33,7 @@ export class AppController {
   async getSession(@Req() req: Request): Promise<UserSession> {
     const user = req.user as User;
 
-    if (user && isUserSession(user)) {
+    if (!isNil(user) && isUserSession(user)) {
       const userSession: UserSession = {
         provider: user.provider,
         providerId: user.providerId,
@@ -42,12 +43,12 @@ export class AppController {
       };
 
       const joinedRooms = await user.joinedRooms;
-      if (joinedRooms != null && joinedRooms.length > 0) {
+      if (joinedRooms !== undefined && joinedRooms.length > 0) {
         const room = joinedRooms[0].room;
         userSession.participatingRoomCode = room.code;
         const host = await room.host;
 
-        if (host != null && host.id === user.id) {
+        if (host !== undefined && host.id === user.id) {
           userSession.isHost = true;
         }
       }

server/src/auth/auth.service.ts

@@ -2,6 +2,7 @@ import { BadRequestException, Injectable, Logger } from '@nestjs/common';
 import { UserService } from '../user/user.service';
 import User from '../entities/user.entity';
 import { ProviderInfo } from 'src/types/user';
+import { isNil } from '@nestjs/common/utils/shared.utils';
 
 @Injectable()
 export class AuthService {
@@ -17,7 +18,7 @@ export class AuthService {
     const user =
       await this.userService.findUserByProviderInfo(mockProviderInfo);
 
-    if (user == null) {
+    if (isNil(user)) {
       this.logger.debug('잘못된 로그인 요청입니다!');
       throw new BadRequestException('잘못된 로그인 요청입니다!');
     }

server/src/problem/dto/random.problem.dto.ts

@@ -11,7 +11,7 @@ export class RandomProblemDto {
     required: true,
     minLength: 1,
   })
-  @Transform(({ value }) => value.split(',').map((v: string) => +v))
+  @Transform(({ value }) => value.split(',').map((v: string) => Number(v)))
   @ArrayUnique()
   @IsNumber({}, { each: true })
   tagIds!: number[];
@@ -21,7 +21,7 @@ export class RandomProblemDto {
     required: true,
     minLength: 1,
   })
-  @Transform(({ value }) => value.split(',').map((v: string) => +v))
+  @Transform(({ value }) => value.split(',').map((v: string) => Number(v)))
   @ArrayUnique()
   @IsNumber({}, { each: true })
   levels!: number[];
@@ -30,7 +30,7 @@ export class RandomProblemDto {
     example: '5',
     required: true,
   })
-  @Transform(({ value }) => +value)
+  @Transform(({ value }) => Number(value))
   @IsNumber()
   @IsNotEmpty()
   @Min(1)

server/src/problem/problem.service.ts

@@ -4,6 +4,7 @@ import Problem from 'src/entities/problem.entity';
 import { ILike, In, Raw, Repository } from 'typeorm';
 import { RandomProblemDto } from './dto/random.problem.dto';
 import { SearchProblemDto } from './dto/search.problem.dto';
+import { isNil } from '@nestjs/common/utils/shared.utils';
 
 @Injectable()
 export class ProblemService {
@@ -57,7 +58,7 @@ export class ProblemService {
     const problemEntities: Problem[] = [];
     for (const bojProblemId of bojProblemIds) {
       const problem = await this.getProblemByBojProblemId(bojProblemId);
-      if (problem == null) {
+      if (isNil(problem)) {
         throw new Error(`bojProblemId ${bojProblemId} not found`);
       }
       problemEntities.push(problem);

server/src/room/room.service.ts

@@ -13,6 +13,7 @@ import { UserService } from 'src/user/user.service';
 import { Repository } from 'typeorm';
 import RoomUser from '../entities/roomUser.entity';
 import { SocketService } from '../socket/socket.service';
+import { isNil } from '@nestjs/common/utils/shared.utils';
 
 @Injectable()
 export class RoomService {
@@ -38,7 +39,7 @@ export class RoomService {
       throw new BadRequestException('이미 참가한 방이 있습니다.');
     }
 
-    if (user.username == null)
+    if (isNil(user.username))
       throw new BadRequestException('username이 없습니다.');
     const code = await this.createRoomCode(user.username);
 
@@ -65,7 +66,7 @@ export class RoomService {
   async joinRoom(user: User, roomCode: string) {
     const joinedRooms = await user.joinedRooms;
 
-    if (joinedRooms != null && joinedRooms.length !== 0) {
+    if (joinedRooms !== undefined && joinedRooms.length > 0) {
       throw new BadRequestException('이미 참가한 방이 있습니다.');
     }
 
@@ -76,7 +77,7 @@ export class RoomService {
       throw new BadRequestException('존재하지 않는 방입니다.');
     }
     const room = roomUsers[0].room;
-    if (room == null) {
+    if (isNil(room)) {
       throw new InternalServerErrorException('방을 찾을 수 없습니다.');
     }
     this.logger.debug(`user ${user.username} joining room ${room.code}...`);
@@ -91,7 +92,7 @@ export class RoomService {
 
   async exitRoom(user: User) {
     const joinedRooms = await user.joinedRooms;
-    if (joinedRooms == null) {
+    if (joinedRooms === undefined) {
       throw new InternalServerErrorException(
         '참가 중인 방을 찾을 수 없습니다.',
       );
@@ -105,21 +106,21 @@ export class RoomService {
     await this.roomUserRepository.remove(roomUser);
 
     const room = roomUser.room;
-    if (room == null) {
+    if (isNil(room)) {
       throw new InternalServerErrorException('방을 찾을 수 없습니다.');
     }
 
     await this.socketService.notifyExit(user.username, room);
 
     const numberOfJoinedUsers = (await room.joinedUsers)?.length;
-    if (numberOfJoinedUsers == null || numberOfJoinedUsers === 0) {
+    if (isNil(numberOfJoinedUsers) || numberOfJoinedUsers === 0) {
       await this.destroyRoom(room);
     }
   }
 
   async findRoomByCode(code: string) {
     const room = await this.roomRepository.findOne({ where: { code } });
-    if (!room) {
+    if (isNil(room)) {
       throw new BadRequestException('존재하지 않는 방입니다.');
     }
     return room;

server/src/socket/socket.gateway.ts

@@ -20,6 +20,7 @@ import { SocketService } from './socket.service';
 import { ProblemService } from 'src/problem/problem.service';
 import { InjectRepository } from '@nestjs/typeorm';
 import { Repository } from 'typeorm';
+import { isNil } from '@nestjs/common/utils/shared.utils';
 
 @WebSocketGateway({
   cors: {
@@ -91,7 +92,7 @@ export class SocketGateway implements OnGatewayConnection, OnGatewayDisconnect {
       provider,
       providerId,
     });
-    if (user == null) throw new WsException('user is null');
+    if (isNil(user)) throw new WsException('user is null');
 
     await this.socketService.gameStart(user, roomInfo);
   }
@@ -109,7 +110,7 @@ export class SocketGateway implements OnGatewayConnection, OnGatewayDisconnect {
       message,
     );
 
-    if (this.server == null) throw new WsException('server is null');
+    if (isNil(this.server)) throw new WsException('server is null');
 
     this.logger.debug(`--> ws: chat-message ${message.body}`);
     this.server.to(room.code).emit('chat-message', message);
@@ -142,9 +143,9 @@ export class SocketGateway implements OnGatewayConnection, OnGatewayDisconnect {
   }
   getUser(client: Socket): User {
     const request = client.request as any;
-    if (request == null) throw new WsException('request is null');
+    if (isNil(request)) throw new WsException('request is null');
     const user = request.user;
-    if (user == null) throw new WsException('user is null');
+    if (isNil(user)) throw new WsException('user is null');
     return user as User;
   }
 }

server/src/socket/socket.service.ts

@@ -54,9 +54,9 @@ export class SocketService {
     const host = await room.host;
     const problems = await room.problems;
 
-    if (roomUsers == null) throw new WsException('roomUsers is null');
-    if (host == null) throw new WsException('host is null');
-    if (problems == null || problems.length === 0)
+    if (roomUsers === undefined) throw new WsException('roomUsers is null');
+    if (host === undefined) throw new WsException('host is null');
+    if (problems === undefined || problems.length === 0)
       throw new WsException('problems is null');
 
     const problemTypes: ProblemType[] = problems.map((problem) => {
@@ -144,7 +144,7 @@ export class SocketService {
     // check if the user is the host of the room
 
     const host = await roomUser.room.host;
-    if (host == null) throw new WsException('host is null');
+    if (host === undefined) throw new WsException('host is null');
     if (host.id !== user.id) {
       throw new WsException('방장이 아닙니다.');
     }
@@ -154,8 +154,8 @@ export class SocketService {
     // update room entity properties: problems, isStarted, endAt
 
     const { problems, duration } = startingRoomInfo;
-    if (problems == null) throw new WsException('problems is null');
-    if (duration == null) throw new WsException('duration is null');
+    if (problems === undefined) throw new WsException('problems is null');
+    if (duration === undefined) throw new WsException('duration is null');
     const bojProblemIds = problems.map((problem) => problem.bojProblemId);
     const problemEntities =
       await this.problemService.getProblemsByBojProblemIds(bojProblemIds);

server/src/submission/submission.service.ts

@@ -11,6 +11,7 @@ import { UserService } from 'src/user/user.service';
 import { Repository } from 'typeorm';
 import { SubmissionDto } from './dto/submission.dto';
 import { SocketService } from '../socket/socket.service';
+import { isNil } from '@nestjs/common/utils/shared.utils';
 
 @Injectable()
 export class SubmissionService {
@@ -44,7 +45,7 @@ export class SubmissionService {
     if (!user) throw new BadRequestException('존재하지 않는 유저입니다.');
 
     const roomUsers = await user.joinedRooms;
-    if (roomUsers == null || roomUsers.length === 0)
+    if (roomUsers === undefined || roomUsers.length === 0)
       throw new BadRequestException('참여중인 방이 없습니다.');
 
     const roomUser = roomUsers[0];
@@ -56,17 +57,17 @@ export class SubmissionService {
     }
 
     const endAt = room.endAt;
-    if (endAt == null || endAt < new Date()) {
+    if (endAt === undefined || endAt < new Date()) {
       throw new BadRequestException('이미 종료된 방입니다.');
     }
 
     const problems = await room.problems;
-    if (problems == null || problems.length === 0)
+    if (problems === undefined || problems.length === 0)
       throw new BadRequestException('문제가 없는 방입니다.');
 
     const problem =
       await this.problemService.getProblemByBojProblemId(bojProblemId);
-    if (problem == null)
+    if (isNil(problem))
       throw new BadRequestException('존재하지 않는 문제입니다.');
 
     if (
@@ -75,7 +76,7 @@ export class SubmissionService {
       throw new BadRequestException('참여중인 방에 없는 문제입니다.');
     }
 
-    if (user.username == null)
+    if (isNil(user.username))
       throw new BadRequestException('username이 없습니다.');
 
     await this.socketService.submitCode(

server/src/user/user.service.ts

@@ -48,15 +48,15 @@ export class UserService {
 
   async findJoinedRooms(user: User) {
     const joinedRooms = await user.joinedRooms;
-    if (joinedRooms == null) {
+    if (joinedRooms === undefined) {
       throw new BadRequestException('joinedRooms is null');
     }
     return joinedRooms;
   }
 
   async getSingleJoinedRoom(user: User) {
     const joinedRooms = await user.joinedRooms;
-    if (joinedRooms == null) {
+    if (joinedRooms === undefined) {
       throw new InternalServerErrorException('joinedRooms is null');
     }
     if (joinedRooms.length !== 1) {