Add username check to doctor

modules/doctor/breaking.go

@@ -58,6 +58,29 @@ func checkUserEmail(ctx context.Context, logger log.Logger, _ bool) error {
 return nil
 }
 
+// From time to time Gitea makes changes to the reserved usernames and which symbols
+// are allowed for various reasons. This check helps with detecting users that, according
+// to our reserved names, don't have a valid username.
+func checkUserName(ctx context.Context, logger log.Logger, _ bool) error {
+var invalidUserCount int64
+if err := iterateUserAccounts(ctx, func(u *user.User) error {
+if err := user.IsUsableUsername(u.Name); err != nil {
+invalidUserCount++
+logger.Warn("User[id=%d] does not have a valid username: %v", u.ID, err)
+}
+return nil
+}); err != nil {
+return fmt.Errorf("iterateUserAccounts: %v", err)
+}
+
+if invalidUserCount == 0 {
+logger.Info("All users have a valid username.")
+} else {
+logger.Warn("%d user(s) have a non-valid username.", invalidUserCount)
+}
+return nil
+}
+
 func init() {
 Register(&Check{
 Title: "Check if users has an valid email address",
@@ -66,4 +89,11 @@ func init() {
 Run: checkUserEmail,
 Priority: 9,
 })
+Register(&Check{
+Title: "Check if users have a valid username",
+Name: "check-user-names",
+IsDefault: false,
+Run: checkUserName,
+Priority: 9,
+})
 }