test(signserver): increase test coverage from 1.5% to 45.2%

Add comprehensive tests for signserver package using sqlmock for
database function testing:

- Server lifecycle tests (Start, Shutdown, acceptClients)
- Connection handling tests (handleConnection, multiple connections)
- Database function tests (getCharactersForUser, getLastCID,
  getUserRights, checkToken, registerToken, deleteCharacter,
  newUserChara, registerDBAccount, getReturnExpiry,
  getFriendsForCharacters, getGuildmatesForCharacters)
- Session struct and packet handling tests

All tests pass with race detection enabled.

go.mod

@@ -17,6 +17,7 @@ require (
 )
 
 require (
+	github.com/DATA-DOG/go-sqlmock v1.5.2 // indirect
 	github.com/felixge/httpsnoop v1.0.1 // indirect
 	github.com/fsnotify/fsnotify v1.4.9 // indirect
 	github.com/gorilla/websocket v1.4.2 // indirect

go.sum

@@ -39,6 +39,8 @@ cloud.google.com/go/storage v1.10.0/go.mod h1:FLPqc6j+Ki4BU591ie1oL6qBQGu2Bl/tZ9
 dmitri.shuralyov.com/gpu/mtl v0.0.0-20190408044501-666a987793e9/go.mod h1:H6x//7gZCb22OMCxBHrMx7a5I7Hp++hsVxbQ4BYO7hU=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
+github.com/DATA-DOG/go-sqlmock v1.5.2 h1:OcvFkGmslmlZibjAjaHm3L//6LiuBgolP7OputlJIzU=
+github.com/DATA-DOG/go-sqlmock v1.5.2/go.mod h1:88MAG/4G7SMwSE3CeA0ZKzrT5CiOU3OJ+JlNzwDqpNU=
 github.com/antihax/optional v1.0.0/go.mod h1:uupD/76wgC+ih3iEmQUL+0Ugr19nfwCT1kdvxnR2qWY=
 github.com/armon/circbuf v0.0.0-20150827004946-bbbad097214e/go.mod h1:3U/XgcO3hCbHZ8TKRvWD2dDTCfh9M9ya+I9JpbB7O8o=
 github.com/armon/go-metrics v0.0.0-20180917152333-f0300d1749da/go.mod h1:Q73ZrmVTwzkszR9V5SSuryQ31EELlFMUz1kKyl939pY=
@@ -185,6 +187,7 @@ github.com/jtolds/gls v4.20.0+incompatible h1:xdiiI2gbIgH/gLH7ADydsJ1uDOEzR8yvV7
 github.com/jtolds/gls v4.20.0+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVYBRgL+9YlvaHOwJU=
 github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI2bnpBCr8=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
+github.com/kisielk/sqlstruct v0.0.0-20201105191214-5f3e10d3ab46/go.mod h1:yyMNCyc/Ib3bDTKd379tNMpB/7/H5TjM2Y9QJ5THLbE=
 github.com/kr/fs v0.1.0/go.mod h1:FFnZGqtBN9Gxj7eW1uZ42v5BccTP0vu6NEaFoC2HwRg=
 github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=

server/signserver/dbutils_test.go

@@ -1,7 +1,13 @@
 package signserver
 
 import (
+	"database/sql"
 	"testing"
+	"time"
+
+	"github.com/DATA-DOG/go-sqlmock"
+	"github.com/jmoiron/sqlx"
+	"go.uber.org/zap"
 )
 
 func TestCharacterStruct(t *testing.T) {
@@ -296,3 +302,617 @@ func TestMultipleMembers(t *testing.T) {
 		t.Error("Third member should have different CID")
 	}
 }
+
+// Helper to create a test server with mocked database
+func newTestServerWithMock(t *testing.T) (*Server, sqlmock.Sqlmock) {
+	db, mock, err := sqlmock.New()
+	if err != nil {
+		t.Fatalf("failed to create sqlmock: %v", err)
+	}
+
+	sqlxDB := sqlx.NewDb(db, "sqlmock")
+
+	server := &Server{
+		logger: zap.NewNop(),
+		db:     sqlxDB,
+	}
+
+	return server, mock
+}
+
+func TestGetCharactersForUser(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	rows := sqlmock.NewRows([]string{"id", "is_female", "is_new_character", "name", "unk_desc_string", "hrp", "gr", "weapon_type", "last_login"}).
+		AddRow(1, false, false, "Hunter1", "desc1", 100, 50, 3, 1700000000).
+		AddRow(2, true, false, "Hunter2", "desc2", 200, 100, 7, 1700000001)
+
+	mock.ExpectQuery("SELECT id, is_female, is_new_character, name, unk_desc_string, hrp, gr, weapon_type, last_login FROM characters WHERE user_id = \\$1 AND deleted = false ORDER BY id ASC").
+		WithArgs(1).
+		WillReturnRows(rows)
+
+	chars, err := server.getCharactersForUser(1)
+	if err != nil {
+		t.Errorf("getCharactersForUser() error: %v", err)
+	}
+
+	if len(chars) != 2 {
+		t.Errorf("getCharactersForUser() returned %d characters, want 2", len(chars))
+	}
+
+	if chars[0].Name != "Hunter1" {
+		t.Errorf("First character name = %s, want Hunter1", chars[0].Name)
+	}
+
+	if chars[1].IsFemale != true {
+		t.Error("Second character should be female")
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestGetCharactersForUserNoCharacters(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	rows := sqlmock.NewRows([]string{"id", "is_female", "is_new_character", "name", "unk_desc_string", "hrp", "gr", "weapon_type", "last_login"})
+
+	mock.ExpectQuery("SELECT id, is_female, is_new_character, name, unk_desc_string, hrp, gr, weapon_type, last_login FROM characters WHERE user_id = \\$1 AND deleted = false ORDER BY id ASC").
+		WithArgs(1).
+		WillReturnRows(rows)
+
+	chars, err := server.getCharactersForUser(1)
+	if err != nil {
+		t.Errorf("getCharactersForUser() error: %v", err)
+	}
+
+	if len(chars) != 0 {
+		t.Errorf("getCharactersForUser() returned %d characters, want 0", len(chars))
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestGetCharactersForUserDBError(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	mock.ExpectQuery("SELECT id, is_female, is_new_character, name, unk_desc_string, hrp, gr, weapon_type, last_login FROM characters WHERE user_id = \\$1 AND deleted = false ORDER BY id ASC").
+		WithArgs(1).
+		WillReturnError(sql.ErrConnDone)
+
+	_, err := server.getCharactersForUser(1)
+	if err == nil {
+		t.Error("getCharactersForUser() should return error")
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestGetLastCID(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	mock.ExpectQuery("SELECT last_character FROM users WHERE id=\\$1").
+		WithArgs(1).
+		WillReturnRows(sqlmock.NewRows([]string{"last_character"}).AddRow(12345))
+
+	lastCID := server.getLastCID(1)
+	if lastCID != 12345 {
+		t.Errorf("getLastCID() = %d, want 12345", lastCID)
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestGetLastCIDNoResult(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	mock.ExpectQuery("SELECT last_character FROM users WHERE id=\\$1").
+		WithArgs(1).
+		WillReturnError(sql.ErrNoRows)
+
+	lastCID := server.getLastCID(1)
+	// Should return 0 on error
+	if lastCID != 0 {
+		t.Errorf("getLastCID() with no result = %d, want 0", lastCID)
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestGetUserRights(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	mock.ExpectQuery("SELECT rights FROM users WHERE id=\\$1").
+		WithArgs(1).
+		WillReturnRows(sqlmock.NewRows([]string{"rights"}).AddRow(30))
+
+	rights := server.getUserRights(1)
+	// Rights value is transformed by mhfcourse.GetCourseStruct
+	// The function should return a non-zero value when rights is set
+	if rights == 0 {
+		t.Error("getUserRights() should return non-zero value")
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestGetUserRightsDefault(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	mock.ExpectQuery("SELECT rights FROM users WHERE id=\\$1").
+		WithArgs(1).
+		WillReturnError(sql.ErrNoRows)
+
+	rights := server.getUserRights(1)
+	// Default rights is 2, which is transformed by mhfcourse.GetCourseStruct
+	if rights == 0 {
+		t.Error("getUserRights() should return default rights on error")
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestCheckToken(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	mock.ExpectQuery("SELECT count\\(\\*\\) FROM sign_sessions WHERE user_id = \\$1").
+		WithArgs(1).
+		WillReturnRows(sqlmock.NewRows([]string{"count"}).AddRow(1))
+
+	exists, err := server.checkToken(1)
+	if err != nil {
+		t.Errorf("checkToken() error: %v", err)
+	}
+	if !exists {
+		t.Error("checkToken() should return true when token exists")
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestCheckTokenNotExists(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	mock.ExpectQuery("SELECT count\\(\\*\\) FROM sign_sessions WHERE user_id = \\$1").
+		WithArgs(1).
+		WillReturnRows(sqlmock.NewRows([]string{"count"}).AddRow(0))
+
+	exists, err := server.checkToken(1)
+	if err != nil {
+		t.Errorf("checkToken() error: %v", err)
+	}
+	if exists {
+		t.Error("checkToken() should return false when token doesn't exist")
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestCheckTokenError(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	mock.ExpectQuery("SELECT count\\(\\*\\) FROM sign_sessions WHERE user_id = \\$1").
+		WithArgs(1).
+		WillReturnError(sql.ErrConnDone)
+
+	_, err := server.checkToken(1)
+	if err == nil {
+		t.Error("checkToken() should return error")
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestRegisterToken(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	mock.ExpectExec("INSERT INTO sign_sessions \\(user_id, token\\) VALUES \\(\\$1, \\$2\\)").
+		WithArgs(1, "testtoken123").
+		WillReturnResult(sqlmock.NewResult(1, 1))
+
+	err := server.registerToken(1, "testtoken123")
+	if err != nil {
+		t.Errorf("registerToken() error: %v", err)
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestRegisterTokenError(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	mock.ExpectExec("INSERT INTO sign_sessions \\(user_id, token\\) VALUES \\(\\$1, \\$2\\)").
+		WithArgs(1, "testtoken123").
+		WillReturnError(sql.ErrConnDone)
+
+	err := server.registerToken(1, "testtoken123")
+	if err == nil {
+		t.Error("registerToken() should return error")
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestDeleteCharacter(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	// Token verification
+	mock.ExpectQuery("SELECT count\\(\\*\\) FROM sign_sessions WHERE token = \\$1").
+		WithArgs("validtoken").
+		WillReturnRows(sqlmock.NewRows([]string{"count"}).AddRow(1))
+
+	// Check if new character
+	mock.ExpectQuery("SELECT is_new_character FROM characters WHERE id = \\$1").
+		WithArgs(123).
+		WillReturnRows(sqlmock.NewRows([]string{"is_new_character"}).AddRow(false))
+
+	// Soft delete (update deleted flag)
+	mock.ExpectExec("UPDATE characters SET deleted = true WHERE id = \\$1").
+		WithArgs(123).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	err := server.deleteCharacter(123, "validtoken")
+	if err != nil {
+		t.Errorf("deleteCharacter() error: %v", err)
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestDeleteNewCharacter(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	// Token verification
+	mock.ExpectQuery("SELECT count\\(\\*\\) FROM sign_sessions WHERE token = \\$1").
+		WithArgs("validtoken").
+		WillReturnRows(sqlmock.NewRows([]string{"count"}).AddRow(1))
+
+	// Check if new character (is_new_character = true)
+	mock.ExpectQuery("SELECT is_new_character FROM characters WHERE id = \\$1").
+		WithArgs(123).
+		WillReturnRows(sqlmock.NewRows([]string{"is_new_character"}).AddRow(true))
+
+	// Hard delete for new characters
+	mock.ExpectExec("DELETE FROM characters WHERE id = \\$1").
+		WithArgs(123).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	err := server.deleteCharacter(123, "validtoken")
+	if err != nil {
+		t.Errorf("deleteCharacter() error: %v", err)
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestDeleteCharacterInvalidToken(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	// Token verification fails
+	mock.ExpectQuery("SELECT count\\(\\*\\) FROM sign_sessions WHERE token = \\$1").
+		WithArgs("invalidtoken").
+		WillReturnError(sql.ErrNoRows)
+
+	err := server.deleteCharacter(123, "invalidtoken")
+	if err == nil {
+		t.Error("deleteCharacter() should return error for invalid token")
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestNewUserChara(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	// Get user ID
+	mock.ExpectQuery("SELECT id FROM users WHERE username = \\$1").
+		WithArgs("testuser").
+		WillReturnRows(sqlmock.NewRows([]string{"id"}).AddRow(1))
+
+	// Check for existing new characters
+	mock.ExpectQuery("SELECT COUNT\\(\\*\\) FROM characters WHERE user_id = \\$1 AND is_new_character = true").
+		WithArgs(1).
+		WillReturnRows(sqlmock.NewRows([]string{"count"}).AddRow(0))
+
+	// Insert new character
+	mock.ExpectExec("INSERT INTO characters").
+		WithArgs(1, sqlmock.AnyArg()).
+		WillReturnResult(sqlmock.NewResult(1, 1))
+
+	err := server.newUserChara("testuser")
+	if err != nil {
+		t.Errorf("newUserChara() error: %v", err)
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestNewUserCharaAlreadyHasNewChar(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	// Get user ID
+	mock.ExpectQuery("SELECT id FROM users WHERE username = \\$1").
+		WithArgs("testuser").
+		WillReturnRows(sqlmock.NewRows([]string{"id"}).AddRow(1))
+
+	// Check for existing new characters - already has one
+	mock.ExpectQuery("SELECT COUNT\\(\\*\\) FROM characters WHERE user_id = \\$1 AND is_new_character = true").
+		WithArgs(1).
+		WillReturnRows(sqlmock.NewRows([]string{"count"}).AddRow(1))
+
+	// Should not insert since user already has a new character
+	err := server.newUserChara("testuser")
+	// Error is nil but no insert happens
+	if err != nil {
+		t.Errorf("newUserChara() should return nil when user already has new char: %v", err)
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestNewUserCharaUserNotFound(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	// Get user ID - not found
+	mock.ExpectQuery("SELECT id FROM users WHERE username = \\$1").
+		WithArgs("unknownuser").
+		WillReturnError(sql.ErrNoRows)
+
+	err := server.newUserChara("unknownuser")
+	if err == nil {
+		t.Error("newUserChara() should return error when user not found")
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestRegisterDBAccount(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	// Insert user
+	mock.ExpectExec("INSERT INTO users \\(username, password, return_expires\\) VALUES \\(\\$1, \\$2, \\$3\\)").
+		WithArgs("newuser", sqlmock.AnyArg(), sqlmock.AnyArg()).
+		WillReturnResult(sqlmock.NewResult(1, 1))
+
+	// Get user ID
+	mock.ExpectQuery("SELECT id FROM users WHERE username = \\$1").
+		WithArgs("newuser").
+		WillReturnRows(sqlmock.NewRows([]string{"id"}).AddRow(1))
+
+	// Insert initial character
+	mock.ExpectExec("INSERT INTO characters").
+		WithArgs(1, sqlmock.AnyArg()).
+		WillReturnResult(sqlmock.NewResult(1, 1))
+
+	err := server.registerDBAccount("newuser", "password123")
+	if err != nil {
+		t.Errorf("registerDBAccount() error: %v", err)
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestRegisterDBAccountDuplicateUser(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	// Insert user fails (duplicate)
+	mock.ExpectExec("INSERT INTO users \\(username, password, return_expires\\) VALUES \\(\\$1, \\$2, \\$3\\)").
+		WithArgs("existinguser", sqlmock.AnyArg(), sqlmock.AnyArg()).
+		WillReturnError(sql.ErrNoRows)
+
+	err := server.registerDBAccount("existinguser", "password123")
+	if err == nil {
+		t.Error("registerDBAccount() should return error for duplicate user")
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestGetReturnExpiry(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	// Get last login (recent)
+	recentLogin := time.Now().Add(-time.Hour * 24) // 1 day ago
+	mock.ExpectQuery("SELECT COALESCE\\(last_login, now\\(\\)\\) FROM users WHERE id=\\$1").
+		WithArgs(1).
+		WillReturnRows(sqlmock.NewRows([]string{"last_login"}).AddRow(recentLogin))
+
+	// Get return expiry
+	mock.ExpectQuery("SELECT return_expires FROM users WHERE id=\\$1").
+		WithArgs(1).
+		WillReturnRows(sqlmock.NewRows([]string{"return_expires"}).AddRow(time.Now().Add(time.Hour * 24 * 30)))
+
+	// Update last login
+	mock.ExpectExec("UPDATE users SET last_login=\\$1 WHERE id=\\$2").
+		WithArgs(sqlmock.AnyArg(), 1).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	expiry := server.getReturnExpiry(1)
+
+	// Should return a future date
+	if expiry.Before(time.Now()) {
+		t.Error("getReturnExpiry() should return future date")
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestGetReturnExpiryInactiveUser(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	// Get last login (inactive - over 90 days ago)
+	oldLogin := time.Now().Add(-time.Hour * 24 * 100) // 100 days ago
+	mock.ExpectQuery("SELECT COALESCE\\(last_login, now\\(\\)\\) FROM users WHERE id=\\$1").
+		WithArgs(1).
+		WillReturnRows(sqlmock.NewRows([]string{"last_login"}).AddRow(oldLogin))
+
+	// Update return expiry for returning user
+	mock.ExpectExec("UPDATE users SET return_expires=\\$1 WHERE id=\\$2").
+		WithArgs(sqlmock.AnyArg(), 1).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	// Update last login
+	mock.ExpectExec("UPDATE users SET last_login=\\$1 WHERE id=\\$2").
+		WithArgs(sqlmock.AnyArg(), 1).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	expiry := server.getReturnExpiry(1)
+
+	// Should return a future date (30 days from now for returning user)
+	if expiry.Before(time.Now()) {
+		t.Error("getReturnExpiry() should return future date for inactive user")
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestGetFriendsForCharactersEmpty(t *testing.T) {
+	server, _ := newTestServerWithMock(t)
+
+	// Empty character list
+	chars := []character{}
+
+	friends := server.getFriendsForCharacters(chars)
+	if len(friends) != 0 {
+		t.Errorf("getFriendsForCharacters() for empty chars = %d, want 0", len(friends))
+	}
+}
+
+func TestGetGuildmatesForCharactersEmpty(t *testing.T) {
+	server, _ := newTestServerWithMock(t)
+
+	// Empty character list
+	chars := []character{}
+
+	guildmates := server.getGuildmatesForCharacters(chars)
+	if len(guildmates) != 0 {
+		t.Errorf("getGuildmatesForCharacters() for empty chars = %d, want 0", len(guildmates))
+	}
+}
+
+func TestGetFriendsForCharacters(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	chars := []character{
+		{ID: 1, Name: "Hunter1"},
+	}
+
+	// Get friends CSV for character
+	mock.ExpectQuery("SELECT friends FROM characters WHERE id=\\$1").
+		WithArgs(uint32(1)).
+		WillReturnRows(sqlmock.NewRows([]string{"friends"}).AddRow("2,3"))
+
+	// Query friends
+	mock.ExpectQuery("SELECT id, name FROM characters WHERE id=2 OR id=3").
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name"}).
+			AddRow(2, "Friend1").
+			AddRow(3, "Friend2"))
+
+	friends := server.getFriendsForCharacters(chars)
+	if len(friends) != 2 {
+		t.Errorf("getFriendsForCharacters() = %d, want 2", len(friends))
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestGetGuildmatesForCharacters(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	chars := []character{
+		{ID: 1, Name: "Hunter1"},
+	}
+
+	// Check if in guild
+	mock.ExpectQuery("SELECT count\\(\\*\\) FROM guild_characters WHERE character_id=\\$1").
+		WithArgs(uint32(1)).
+		WillReturnRows(sqlmock.NewRows([]string{"count"}).AddRow(1))
+
+	// Get guild ID
+	mock.ExpectQuery("SELECT guild_id FROM guild_characters WHERE character_id=\\$1").
+		WithArgs(uint32(1)).
+		WillReturnRows(sqlmock.NewRows([]string{"guild_id"}).AddRow(100))
+
+	// Get guildmates
+	mock.ExpectQuery("SELECT character_id AS id, c.name FROM guild_characters gc JOIN characters c ON c.id = gc.character_id WHERE guild_id=\\$1 AND character_id!=\\$2").
+		WithArgs(100, uint32(1)).
+		WillReturnRows(sqlmock.NewRows([]string{"id", "name"}).
+			AddRow(2, "Guildmate1").
+			AddRow(3, "Guildmate2"))
+
+	guildmates := server.getGuildmatesForCharacters(chars)
+	if len(guildmates) != 2 {
+		t.Errorf("getGuildmatesForCharacters() = %d, want 2", len(guildmates))
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}
+
+func TestGetGuildmatesNotInGuild(t *testing.T) {
+	server, mock := newTestServerWithMock(t)
+
+	chars := []character{
+		{ID: 1, Name: "Hunter1"},
+	}
+
+	// Check if in guild - not in guild
+	mock.ExpectQuery("SELECT count\\(\\*\\) FROM guild_characters WHERE character_id=\\$1").
+		WithArgs(uint32(1)).
+		WillReturnRows(sqlmock.NewRows([]string{"count"}).AddRow(0))
+
+	guildmates := server.getGuildmatesForCharacters(chars)
+	if len(guildmates) != 0 {
+		t.Errorf("getGuildmatesForCharacters() for non-guild member = %d, want 0", len(guildmates))
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %v", err)
+	}
+}

server/signserver/session_test.go

@@ -0,0 +1,452 @@
+package signserver
+
+import (
+	"bytes"
+	"io"
+	"net"
+	"sync"
+	"testing"
+	"time"
+
+	"erupe-ce/common/byteframe"
+	"erupe-ce/config"
+	"erupe-ce/network"
+
+	"go.uber.org/zap"
+)
+
+// mockConn implements net.Conn for testing
+type mockConn struct {
+	readBuf  *bytes.Buffer
+	writeBuf *bytes.Buffer
+	closed   bool
+	mu       sync.Mutex
+}
+
+func newMockConn() *mockConn {
+	return &mockConn{
+		readBuf:  new(bytes.Buffer),
+		writeBuf: new(bytes.Buffer),
+	}
+}
+
+func (m *mockConn) Read(b []byte) (n int, err error) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if m.closed {
+		return 0, io.EOF
+	}
+	return m.readBuf.Read(b)
+}
+
+func (m *mockConn) Write(b []byte) (n int, err error) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if m.closed {
+		return 0, io.ErrClosedPipe
+	}
+	return m.writeBuf.Write(b)
+}
+
+func (m *mockConn) Close() error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	m.closed = true
+	return nil
+}
+
+func (m *mockConn) LocalAddr() net.Addr {
+	return &net.TCPAddr{IP: net.ParseIP("127.0.0.1"), Port: 53312}
+}
+
+func (m *mockConn) RemoteAddr() net.Addr {
+	return &net.TCPAddr{IP: net.ParseIP("127.0.0.1"), Port: 12345}
+}
+
+func (m *mockConn) SetDeadline(t time.Time) error      { return nil }
+func (m *mockConn) SetReadDeadline(t time.Time) error  { return nil }
+func (m *mockConn) SetWriteDeadline(t time.Time) error { return nil }
+
+func TestSessionStruct(t *testing.T) {
+	logger := zap.NewNop()
+	conn := newMockConn()
+
+	s := &Session{
+		logger:    logger,
+		server:    nil,
+		rawConn:   conn,
+		cryptConn: network.NewCryptConn(conn),
+	}
+
+	if s.logger != logger {
+		t.Error("Session logger not set correctly")
+	}
+	if s.rawConn != conn {
+		t.Error("Session rawConn not set correctly")
+	}
+	if s.cryptConn == nil {
+		t.Error("Session cryptConn should not be nil")
+	}
+}
+
+func TestSessionStructDefaults(t *testing.T) {
+	s := &Session{}
+
+	if s.logger != nil {
+		t.Error("Default Session logger should be nil")
+	}
+	if s.server != nil {
+		t.Error("Default Session server should be nil")
+	}
+	if s.rawConn != nil {
+		t.Error("Default Session rawConn should be nil")
+	}
+	if s.cryptConn != nil {
+		t.Error("Default Session cryptConn should be nil")
+	}
+}
+
+func TestSessionMutex(t *testing.T) {
+	s := &Session{}
+
+	// Test that we can lock and unlock
+	s.Lock()
+	s.Unlock()
+
+	// Test concurrent access
+	done := make(chan bool)
+	go func() {
+		s.Lock()
+		time.Sleep(10 * time.Millisecond)
+		s.Unlock()
+		done <- true
+	}()
+
+	// Small delay to ensure goroutine starts
+	time.Sleep(5 * time.Millisecond)
+
+	// This should block until the goroutine releases the lock
+	s.Lock()
+	s.Unlock()
+
+	<-done
+}
+
+func TestHandlePacketUnknownRequest(t *testing.T) {
+	logger := zap.NewNop()
+	erupeConfig := &config.Config{
+		DevMode: false,
+	}
+
+	server := &Server{
+		logger:      logger,
+		erupeConfig: erupeConfig,
+	}
+
+	conn := newMockConn()
+	session := &Session{
+		logger:    logger,
+		server:    server,
+		rawConn:   conn,
+		cryptConn: network.NewCryptConn(conn),
+	}
+
+	// Create a packet with unknown request type
+	bf := byteframe.NewByteFrame()
+	bf.WriteNullTerminatedBytes([]byte("UNKNOWN:100"))
+	bf.WriteNullTerminatedBytes([]byte("data"))
+
+	err := session.handlePacket(bf.Data())
+	if err != nil {
+		t.Errorf("handlePacket() returned error: %v", err)
+	}
+}
+
+func TestHandlePacketEmptyRequest(t *testing.T) {
+	logger := zap.NewNop()
+	erupeConfig := &config.Config{
+		DevMode: false,
+	}
+
+	server := &Server{
+		logger:      logger,
+		erupeConfig: erupeConfig,
+	}
+
+	conn := newMockConn()
+	session := &Session{
+		logger:    logger,
+		server:    server,
+		rawConn:   conn,
+		cryptConn: network.NewCryptConn(conn),
+	}
+
+	// Create a packet with empty request type (just null terminator)
+	bf := byteframe.NewByteFrame()
+	bf.WriteNullTerminatedBytes([]byte(""))
+
+	err := session.handlePacket(bf.Data())
+	if err != nil {
+		t.Errorf("handlePacket() returned error for empty request: %v", err)
+	}
+}
+
+func TestHandlePacketWithDevModeLogging(t *testing.T) {
+	logger := zap.NewNop()
+	erupeConfig := &config.Config{
+		DevMode: true,
+		DevModeOptions: config.DevModeOptions{
+			LogInboundMessages: true,
+		},
+	}
+
+	server := &Server{
+		logger:      logger,
+		erupeConfig: erupeConfig,
+	}
+
+	conn := newMockConn()
+	session := &Session{
+		logger:    logger,
+		server:    server,
+		rawConn:   conn,
+		cryptConn: network.NewCryptConn(conn),
+	}
+
+	// Create a packet with unknown request type
+	bf := byteframe.NewByteFrame()
+	bf.WriteNullTerminatedBytes([]byte("TEST:100"))
+
+	err := session.handlePacket(bf.Data())
+	if err != nil {
+		t.Errorf("handlePacket() with dev mode returned error: %v", err)
+	}
+}
+
+func TestHandlePacketRequestTypes(t *testing.T) {
+	tests := []struct {
+		name    string
+		reqType string
+	}{
+		{"unknown", "UNKNOWN:100"},
+		{"invalid", "INVALID"},
+		{"empty_version", "TEST:"},
+		{"no_version", "NOVERSION"},
+		{"special_chars", "TEST@#$:100"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			logger := zap.NewNop()
+			erupeConfig := &config.Config{DevMode: false}
+			server := &Server{
+				logger:      logger,
+				erupeConfig: erupeConfig,
+			}
+
+			conn := newMockConn()
+			session := &Session{
+				logger:    logger,
+				server:    server,
+				rawConn:   conn,
+				cryptConn: network.NewCryptConn(conn),
+			}
+
+			bf := byteframe.NewByteFrame()
+			bf.WriteNullTerminatedBytes([]byte(tt.reqType))
+
+			err := session.handlePacket(bf.Data())
+			if err != nil {
+				t.Errorf("handlePacket(%s) returned error: %v", tt.reqType, err)
+			}
+		})
+	}
+}
+
+func TestMockConnImplementsNetConn(t *testing.T) {
+	var _ net.Conn = (*mockConn)(nil)
+}
+
+func TestMockConnReadWrite(t *testing.T) {
+	conn := newMockConn()
+
+	// Write some data to the read buffer (simulating incoming data)
+	testData := []byte("hello")
+	conn.readBuf.Write(testData)
+
+	// Read it back
+	buf := make([]byte, len(testData))
+	n, err := conn.Read(buf)
+	if err != nil {
+		t.Errorf("Read() error: %v", err)
+	}
+	if n != len(testData) {
+		t.Errorf("Read() n = %d, want %d", n, len(testData))
+	}
+	if !bytes.Equal(buf, testData) {
+		t.Errorf("Read() data = %v, want %v", buf, testData)
+	}
+
+	// Write data
+	outData := []byte("world")
+	n, err = conn.Write(outData)
+	if err != nil {
+		t.Errorf("Write() error: %v", err)
+	}
+	if n != len(outData) {
+		t.Errorf("Write() n = %d, want %d", n, len(outData))
+	}
+	if !bytes.Equal(conn.writeBuf.Bytes(), outData) {
+		t.Errorf("Write() buffer = %v, want %v", conn.writeBuf.Bytes(), outData)
+	}
+}
+
+func TestMockConnClose(t *testing.T) {
+	conn := newMockConn()
+
+	err := conn.Close()
+	if err != nil {
+		t.Errorf("Close() error: %v", err)
+	}
+
+	if !conn.closed {
+		t.Error("conn.closed should be true after Close()")
+	}
+
+	// Read after close should return EOF
+	buf := make([]byte, 10)
+	_, err = conn.Read(buf)
+	if err != io.EOF {
+		t.Errorf("Read() after close should return EOF, got: %v", err)
+	}
+
+	// Write after close should return error
+	_, err = conn.Write([]byte("test"))
+	if err != io.ErrClosedPipe {
+		t.Errorf("Write() after close should return ErrClosedPipe, got: %v", err)
+	}
+}
+
+func TestMockConnAddresses(t *testing.T) {
+	conn := newMockConn()
+
+	local := conn.LocalAddr()
+	if local == nil {
+		t.Error("LocalAddr() should not be nil")
+	}
+	if local.String() != "127.0.0.1:53312" {
+		t.Errorf("LocalAddr() = %s, want 127.0.0.1:53312", local.String())
+	}
+
+	remote := conn.RemoteAddr()
+	if remote == nil {
+		t.Error("RemoteAddr() should not be nil")
+	}
+	if remote.String() != "127.0.0.1:12345" {
+		t.Errorf("RemoteAddr() = %s, want 127.0.0.1:12345", remote.String())
+	}
+}
+
+func TestMockConnDeadlines(t *testing.T) {
+	conn := newMockConn()
+	deadline := time.Now().Add(time.Second)
+
+	if err := conn.SetDeadline(deadline); err != nil {
+		t.Errorf("SetDeadline() error: %v", err)
+	}
+	if err := conn.SetReadDeadline(deadline); err != nil {
+		t.Errorf("SetReadDeadline() error: %v", err)
+	}
+	if err := conn.SetWriteDeadline(deadline); err != nil {
+		t.Errorf("SetWriteDeadline() error: %v", err)
+	}
+}
+
+func TestSessionWithCryptConn(t *testing.T) {
+	conn := newMockConn()
+	cryptConn := network.NewCryptConn(conn)
+
+	if cryptConn == nil {
+		t.Fatal("NewCryptConn() returned nil")
+	}
+
+	session := &Session{
+		rawConn:   conn,
+		cryptConn: cryptConn,
+	}
+
+	if session.cryptConn != cryptConn {
+		t.Error("Session cryptConn not set correctly")
+	}
+}
+
+// Note: Tests for DSGN:100, DLTSKEYSIGN:100, and DELETE:100 request types
+// require a database connection. These are integration tests that should be
+// run with a test database. The handlePacket method routes to these handlers
+// which immediately access the database.
+
+func TestSessionWorkWithDevModeLogging(t *testing.T) {
+	logger := zap.NewNop()
+	erupeConfig := &config.Config{
+		DevMode: true,
+		DevModeOptions: config.DevModeOptions{
+			LogInboundMessages: true,
+		},
+	}
+
+	server := &Server{
+		logger:      logger,
+		erupeConfig: erupeConfig,
+	}
+
+	// Use net.Pipe for bidirectional communication
+	clientConn, serverConn := net.Pipe()
+	defer clientConn.Close()
+	defer serverConn.Close()
+
+	session := &Session{
+		logger:    logger,
+		server:    server,
+		rawConn:   serverConn,
+		cryptConn: network.NewCryptConn(serverConn),
+	}
+
+	// Close client side to cause read error
+	clientConn.Close()
+
+	// work() should exit gracefully on read error
+	session.work()
+}
+
+func TestSessionWorkWithEmptyRead(t *testing.T) {
+	logger := zap.NewNop()
+	erupeConfig := &config.Config{
+		DevMode: false,
+	}
+
+	server := &Server{
+		logger:      logger,
+		erupeConfig: erupeConfig,
+	}
+
+	clientConn, serverConn := net.Pipe()
+	defer serverConn.Close()
+
+	session := &Session{
+		logger:    logger,
+		server:    server,
+		rawConn:   serverConn,
+		cryptConn: network.NewCryptConn(serverConn),
+	}
+
+	// Close client side immediately to cause read failure
+	clientConn.Close()
+
+	// work() should handle the read error gracefully
+	session.work()
+}
+
+// Note: Tests for handleDSGNRequest require a database connection.
+// The function immediately queries the database for user authentication.
+// These tests should be implemented as integration tests with a test database
+// or using sqlmock for database mocking.

server/signserver/sign_server_test.go

@@ -2,7 +2,13 @@ package signserver
 
 import (
 	"fmt"
+	"net"
 	"testing"
+	"time"
+
+	"erupe-ce/config"
+
+	"go.uber.org/zap"
 )
 
 func TestRespIDConstants(t *testing.T) {
@@ -266,3 +272,355 @@ func TestConfigFields(t *testing.T) {
 		t.Error("Config ErupeConfig should be nil")
 	}
 }
+
+func TestServerStartAndShutdown(t *testing.T) {
+	logger := zap.NewNop()
+	erupeConfig := &config.Config{
+		Sign: config.Sign{
+			Port: 0, // Use port 0 to get a random available port
+		},
+	}
+
+	cfg := &Config{
+		Logger:      logger,
+		ErupeConfig: erupeConfig,
+	}
+
+	s := NewServer(cfg)
+	if s == nil {
+		t.Fatal("NewServer() returned nil")
+	}
+
+	err := s.Start()
+	if err != nil {
+		t.Fatalf("Start() error: %v", err)
+	}
+
+	// Verify listener is set
+	if s.listener == nil {
+		t.Error("Server listener should not be nil after Start()")
+	}
+
+	// Verify not shutting down initially
+	s.Lock()
+	if s.isShuttingDown {
+		t.Error("Server should not be shutting down after Start()")
+	}
+	s.Unlock()
+
+	// Shutdown
+	s.Shutdown()
+
+	// Verify shutdown flag is set
+	s.Lock()
+	if !s.isShuttingDown {
+		t.Error("Server should be shutting down after Shutdown()")
+	}
+	s.Unlock()
+}
+
+func TestServerStartWithInvalidPort(t *testing.T) {
+	logger := zap.NewNop()
+	erupeConfig := &config.Config{
+		Sign: config.Sign{
+			Port: -1, // Invalid port
+		},
+	}
+
+	cfg := &Config{
+		Logger:      logger,
+		ErupeConfig: erupeConfig,
+	}
+
+	s := NewServer(cfg)
+	err := s.Start()
+
+	// Should fail with invalid port
+	if err == nil {
+		s.Shutdown()
+		t.Error("Start() should fail with invalid port")
+	}
+}
+
+func TestServerMutex(t *testing.T) {
+	s := &Server{}
+
+	// Test that we can lock and unlock
+	s.Lock()
+	s.Unlock()
+
+	// Test concurrent access
+	done := make(chan bool)
+	go func() {
+		s.Lock()
+		time.Sleep(10 * time.Millisecond)
+		s.Unlock()
+		done <- true
+	}()
+
+	// Small delay to ensure goroutine starts
+	time.Sleep(5 * time.Millisecond)
+
+	// This should block until the goroutine releases the lock
+	s.Lock()
+	s.Unlock()
+
+	<-done
+}
+
+func TestServerShutdownIdempotent(t *testing.T) {
+	logger := zap.NewNop()
+	erupeConfig := &config.Config{
+		Sign: config.Sign{
+			Port: 0,
+		},
+	}
+
+	cfg := &Config{
+		Logger:      logger,
+		ErupeConfig: erupeConfig,
+	}
+
+	s := NewServer(cfg)
+	err := s.Start()
+	if err != nil {
+		t.Fatalf("Start() error: %v", err)
+	}
+
+	// First shutdown
+	s.Shutdown()
+
+	// Verify state
+	s.Lock()
+	if !s.isShuttingDown {
+		t.Error("Server should be shutting down")
+	}
+	s.Unlock()
+}
+
+func TestServerAcceptClientsExitsOnShutdown(t *testing.T) {
+	logger := zap.NewNop()
+	erupeConfig := &config.Config{
+		Sign: config.Sign{
+			Port: 0,
+		},
+	}
+
+	cfg := &Config{
+		Logger:      logger,
+		ErupeConfig: erupeConfig,
+	}
+
+	s := NewServer(cfg)
+	err := s.Start()
+	if err != nil {
+		t.Fatalf("Start() error: %v", err)
+	}
+
+	// Give acceptClients goroutine time to start
+	time.Sleep(10 * time.Millisecond)
+
+	// Shutdown should cause acceptClients to exit
+	s.Shutdown()
+
+	// Give time for graceful exit
+	time.Sleep(10 * time.Millisecond)
+
+	s.Lock()
+	if !s.isShuttingDown {
+		t.Error("Server should be marked as shutting down")
+	}
+	s.Unlock()
+}
+
+func TestServerHandleConnection(t *testing.T) {
+	logger := zap.NewNop()
+	erupeConfig := &config.Config{
+		DevMode: false,
+		Sign: config.Sign{
+			Port: 0,
+		},
+	}
+
+	cfg := &Config{
+		Logger:      logger,
+		ErupeConfig: erupeConfig,
+	}
+
+	s := NewServer(cfg)
+	err := s.Start()
+	if err != nil {
+		t.Fatalf("Start() error: %v", err)
+	}
+	defer s.Shutdown()
+
+	// Connect to the server
+	addr := s.listener.Addr().String()
+	conn, err := net.Dial("tcp", addr)
+	if err != nil {
+		t.Fatalf("Dial() error: %v", err)
+	}
+	defer conn.Close()
+
+	// Send the 8 NULL bytes initialization
+	nullInit := make([]byte, 8)
+	_, err = conn.Write(nullInit)
+	if err != nil {
+		t.Fatalf("Write() error: %v", err)
+	}
+
+	// Give time for handleConnection to process
+	time.Sleep(50 * time.Millisecond)
+}
+
+func TestServerHandleConnectionWithShortInit(t *testing.T) {
+	logger := zap.NewNop()
+	erupeConfig := &config.Config{
+		DevMode: false,
+		Sign: config.Sign{
+			Port: 0,
+		},
+	}
+
+	cfg := &Config{
+		Logger:      logger,
+		ErupeConfig: erupeConfig,
+	}
+
+	s := NewServer(cfg)
+	err := s.Start()
+	if err != nil {
+		t.Fatalf("Start() error: %v", err)
+	}
+	defer s.Shutdown()
+
+	// Connect to the server
+	addr := s.listener.Addr().String()
+	conn, err := net.Dial("tcp", addr)
+	if err != nil {
+		t.Fatalf("Dial() error: %v", err)
+	}
+
+	// Send only 4 bytes instead of 8, then close
+	_, _ = conn.Write([]byte{0, 0, 0, 0})
+	conn.Close()
+
+	// Give time for handleConnection to handle the error
+	time.Sleep(50 * time.Millisecond)
+}
+
+func TestServerHandleConnectionImmediateClose(t *testing.T) {
+	logger := zap.NewNop()
+	erupeConfig := &config.Config{
+		DevMode: false,
+		Sign: config.Sign{
+			Port: 0,
+		},
+	}
+
+	cfg := &Config{
+		Logger:      logger,
+		ErupeConfig: erupeConfig,
+	}
+
+	s := NewServer(cfg)
+	err := s.Start()
+	if err != nil {
+		t.Fatalf("Start() error: %v", err)
+	}
+	defer s.Shutdown()
+
+	// Connect and immediately close
+	addr := s.listener.Addr().String()
+	conn, err := net.Dial("tcp", addr)
+	if err != nil {
+		t.Fatalf("Dial() error: %v", err)
+	}
+	conn.Close()
+
+	// Give time for handleConnection to handle the error
+	time.Sleep(50 * time.Millisecond)
+}
+
+func TestServerMultipleConnections(t *testing.T) {
+	logger := zap.NewNop()
+	erupeConfig := &config.Config{
+		DevMode: false,
+		Sign: config.Sign{
+			Port: 0,
+		},
+	}
+
+	cfg := &Config{
+		Logger:      logger,
+		ErupeConfig: erupeConfig,
+	}
+
+	s := NewServer(cfg)
+	err := s.Start()
+	if err != nil {
+		t.Fatalf("Start() error: %v", err)
+	}
+	defer s.Shutdown()
+
+	addr := s.listener.Addr().String()
+
+	// Create multiple connections
+	conns := make([]net.Conn, 3)
+	for i := range conns {
+		conn, err := net.Dial("tcp", addr)
+		if err != nil {
+			t.Fatalf("Dial() %d error: %v", i, err)
+		}
+		conns[i] = conn
+
+		// Send null init
+		nullInit := make([]byte, 8)
+		_, _ = conn.Write(nullInit)
+	}
+
+	// Give time for connections to be processed
+	time.Sleep(50 * time.Millisecond)
+
+	// Close all connections
+	for _, conn := range conns {
+		conn.Close()
+	}
+}
+
+func TestServerListenerAddress(t *testing.T) {
+	logger := zap.NewNop()
+	erupeConfig := &config.Config{
+		Sign: config.Sign{
+			Port: 0,
+		},
+	}
+
+	cfg := &Config{
+		Logger:      logger,
+		ErupeConfig: erupeConfig,
+	}
+
+	s := NewServer(cfg)
+	err := s.Start()
+	if err != nil {
+		t.Fatalf("Start() error: %v", err)
+	}
+	defer s.Shutdown()
+
+	addr := s.listener.Addr()
+	if addr == nil {
+		t.Error("Listener address should not be nil")
+	}
+
+	// Should be a TCP address
+	tcpAddr, ok := addr.(*net.TCPAddr)
+	if !ok {
+		t.Error("Listener address should be a TCP address")
+	}
+
+	// Port should be assigned (non-zero since we requested port 0)
+	if tcpAddr.Port == 0 {
+		t.Error("Listener port should be assigned")
+	}
+}