📝 Add docstrings to develop

src/main/java/com/dnd/moddo/domain/auth/controller/AuthController.java

@@ -33,6 +33,11 @@ public class AuthController {
 	private final KakaoClient kakaoClient;
 	private final CookieProperties cookieProperties;
 
+	/**
+	 * Issues a guest user access token and sets it as an HTTP-only cookie in the response.
+	 *
+	 * @return a response containing the guest user's token and the access token cookie.
+	 */
 	@GetMapping("/user/guest/token")
 	public ResponseEntity<TokenResponse> getGuestToken() {
 		TokenResponse tokenResponse = authService.createGuestUser();
@@ -44,11 +49,24 @@ public ResponseEntity<TokenResponse> getGuestToken() {
 			.body(tokenResponse);
 	}
 
+	/**
+	 * Reissues an access token using the provided refresh token.
+	 *
+	 * @param refreshToken the refresh token from the Authorization header; must not be blank
+	 * @return a response containing the new access token and related information
+	 */
 	@PutMapping("/user/reissue/token")
 	public RefreshResponse reissueAccessToken(@RequestHeader(value = "Authorization") @NotBlank String refreshToken) {
 		return refreshTokenService.execute(refreshToken);
 	}
 
+	/**
+	 * Handles the Kakao OAuth2 login callback by exchanging the authorization code for a Kakao access token,
+	 * obtaining or creating a user token, and setting it as an HTTP-only cookie in the response.
+	 *
+	 * @param code the OAuth2 authorization code received from Kakao after user authentication
+	 * @return a response with status 200 OK and the access token set in an HTTP-only cookie
+	 */
 	@GetMapping("/login/oauth2/callback")
 	public ResponseEntity<Void> kakaoLoginCallback(@RequestParam String code) {
 		KakaoTokenResponse kakaoTokenResponse = kakaoClient.join(code);
@@ -62,6 +80,13 @@ public ResponseEntity<Void> kakaoLoginCallback(@RequestParam String code) {
 			.build();
 	}
 
+	/**
+	 * Logs out the user by expiring the "accessToken" cookie.
+	 *
+	 * Sets an HTTP-only "accessToken" cookie with a max age of zero to remove it from the client, effectively logging out the user.
+	 *
+	 * @return a 200 OK response with the expired cookie set in the response header
+	 */
 	@GetMapping("/logout")
 	public ResponseEntity<Void> kakaoLogout() {
 		String cookie = expireCookie("accessToken").toString();
@@ -71,6 +96,13 @@ public ResponseEntity<Void> kakaoLogout() {
 			.build();
 	}
 
+	/**
+	 * Creates an HTTP cookie with the specified name and value, applying properties from the configured CookieProperties.
+	 *
+	 * @param name the name of the cookie
+	 * @param key the value to set for the cookie
+	 * @return a ResponseCookie configured with security and path attributes
+	 */
 	private ResponseCookie createCookie(String name, String key) {
 		return ResponseCookie.from(name, key)
 			.httpOnly(cookieProperties.httpOnly())
@@ -83,6 +115,15 @@ private ResponseCookie createCookie(String name, String key) {
 
 	}
 
+	/**
+	 * Creates a ResponseCookie with the specified name that is immediately expired.
+	 *
+	 * The cookie is configured with properties from {@code cookieProperties} and a max age of zero,
+	 * causing it to be removed from the client.
+	 *
+	 * @param name the name of the cookie to expire
+	 * @return a ResponseCookie configured to expire immediately
+	 */
 	private ResponseCookie expireCookie(String name) {
 		return ResponseCookie.from(name, null)
 			.httpOnly(cookieProperties.httpOnly())

src/main/java/com/dnd/moddo/domain/auth/service/AuthService.java

@@ -32,6 +32,13 @@ public class AuthService {
 	@Value("${kakao.auth.redirect_uri}")
 	String redirect_uri;
 
+	/**
+	 * Creates a new guest user with a unique email and returns a JWT token for authentication.
+	 *
+	 * The guest user is assigned the name "Guest" and is not marked as a member.
+	 *
+	 * @return a JWT token representing the newly created guest user
+	 */
 	@Transactional
 	public TokenResponse createGuestUser() {
 		String guestEmail = "guest-" + UUID.randomUUID() + "@guest.com";
@@ -42,6 +49,17 @@ public TokenResponse createGuestUser() {
 			guestUser.getIsMember());
 	}
 
+	/**
+	 * Creates and persists a new user with the specified email, name, and membership status.
+	 *
+	 * The user is assigned the USER authority, a null profile, the current time as the creation date,
+	 * and an expiration date set to one month from creation.
+	 *
+	 * @param email the user's email address
+	 * @param name the user's display name
+	 * @param isMember whether the user is a registered member
+	 * @return the saved User entity
+	 */
 	private User createUser(String email, String name, boolean isMember) {
 		User user = User.builder()
 			.email(email)
@@ -56,6 +74,14 @@ private User createUser(String email, String name, boolean isMember) {
 		return userRepository.save(user);
 	}
 
+	/**
+	 * Retrieves or creates a user based on Kakao OAuth profile and returns a JWT token for authentication.
+	 *
+	 * If a user with the Kakao email does not exist, a new user is created using the Kakao profile information and marked as a member.
+	 *
+	 * @param token the Kakao OAuth access token
+	 * @return a JWT token response containing authentication details for the Kakao user
+	 */
 	@Transactional
 	public TokenResponse getOrCreateKakaoUserToken(String token) {
 		KakaoProfile kakaoProfile = kakaoClient.getKakaoProfile(token);

src/main/java/com/dnd/moddo/domain/auth/service/KakaoClient.java

@@ -30,6 +30,14 @@ public class KakaoClient {
 
 	private final RestClient.Builder builder;
 
+	/**
+	 * Exchanges an authorization code for a Kakao OAuth access token.
+	 *
+	 * @param code the authorization code received from Kakao after user authentication
+	 * @return the response containing the Kakao OAuth access token and related information
+	 * @throws ModdoException if an HTTP error occurs during the token request
+	 * @throws IllegalArgumentException if a non-HTTP error occurs during the token request
+	 */
 	public KakaoTokenResponse join(String code) {
 		RestClient restClient = builder.build();
 
@@ -59,6 +67,13 @@ public KakaoTokenResponse join(String code) {
 		}
 	}
 
+	/**
+	 * Retrieves the Kakao user profile associated with the provided access token.
+	 *
+	 * @param token the OAuth access token issued by Kakao
+	 * @return the user's Kakao profile information
+	 * @throws ModdoException if an HTTP error occurs or the profile cannot be retrieved
+	 */
 	public KakaoProfile getKakaoProfile(String token) {
 		RestClient restClient = builder.build();
 

src/test/java/com/dnd/moddo/global/support/UserTestFactory.java

@@ -7,6 +7,15 @@
 import com.dnd.moddo.domain.user.entity.User;
 
 public class UserTestFactory {
+	/**
+	 * Creates a default guest User instance with preset values for testing.
+	 *
+	 * The returned User has the name "연노른자", email "guest-UUID1@guest.com", profile image "profile.png",
+	 * a boolean flag set to false, authority set to USER, and timestamps for creation and expiration
+	 * set to the current time and seven days later, respectively.
+	 *
+	 * @return a User object representing a default guest user for test scenarios
+	 */
 	public static User createGuestDefault() {
 		LocalDateTime time = LocalDateTime.now();
 
@@ -20,6 +29,16 @@ public static User createGuestDefault() {
 			time.plusDays(7));
 	}
 
+	/**
+	 * Creates a test User instance with the specified email and default attributes.
+	 *
+	 * The returned User has the name "연노른자", the provided email, profile image "profile.png",
+	 * a boolean flag set to true, authority set to USER, and timestamps for creation and expiration
+	 * set to the current time and seven days later, respectively.
+	 *
+	 * @param email the email address to assign to the User
+	 * @return a User instance configured for testing with the given email
+	 */
 	public static User createWithEmail(String email) {
 		LocalDateTime time = LocalDateTime.now();