Fix potential assignee query for repo (#18994)

* Fix potential assignee query for repo

* Add tests for `GetRepoAssignees`

- As per https://github.com/go-gitea/gitea/pull/18994#issuecomment-1058506640

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Gusted <williamzijl7@hotmail.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

models/repo.go

@@ -153,7 +153,7 @@ func getRepoAssignees(ctx context.Context, repo *repo_model.Repository) (_ []*us
 	userIDs := make([]int64, 0, 10)
 	if err = e.Table("access").
 		Where("repo_id = ? AND mode >= ?", repo.ID, perm.AccessModeWrite).
-		Select("id").
+		Select("user_id").
 		Find(&userIDs); err != nil {
 		return nil, err
 	}

models/repo_test.go

@@ -167,3 +167,21 @@ func TestLinkedRepository(t *testing.T) {
 		})
 	}
 }
+
+func TestRepoAssignees(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	repo2 := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 2}).(*repo_model.Repository)
+	users, err := GetRepoAssignees(repo2)
+	assert.NoError(t, err)
+	assert.Len(t, users, 1)
+	assert.Equal(t, users[0].ID, int64(2))
+
+	repo21 := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 21}).(*repo_model.Repository)
+	users, err = GetRepoAssignees(repo21)
+	assert.NoError(t, err)
+	assert.Len(t, users, 3)
+	assert.Equal(t, users[0].ID, int64(15))
+	assert.Equal(t, users[1].ID, int64(18))
+	assert.Equal(t, users[2].ID, int64(16))
+}