Improve username behavior

Course3/Lab4/validations.org

@@ -0,0 +1,31 @@
+#!/usr/bin/env python3
+
+import re
+
+def validate_user(username, minlen):
+    """Checks if the received username matches the required conditions."""
+    if type(username) != str:
+        raise TypeError("username must be a string")
+    if minlen < 1:
+        raise ValueError("minlen must be at least 1")
+
+    # Usernames can't be shorter than minlen
+    if len(username) < minlen:
+        return False
+    # Usernames can only use letters, numbers, dots and underscores
+    if not re.match('^[a-z0-9._]*$', username):
+        return False
+    # Usernames can't begin with a number
+    if username[0].isnumeric():
+        return False
+    return True
+
+print(validate_user("blue.kale", 3)) # True
+
+print(validate_user(".blue.kale", 3)) # Currently True, should be False
+
+print(validate_user("red_quinoa", 4)) # True
+
+print(validate_user("_red_quinoa", 4)) # Currently True, should be False
+
+

Course3/Lab4/validations.py

@@ -3,22 +3,50 @@
 import re
 
 def validate_user(username, minlen):
+
     """Checks if the received username matches the required conditions."""
+
     if type(username) != str:
+
         raise TypeError("username must be a string")
+
     if minlen < 1:
+
         raise ValueError("minlen must be at least 1")
-
+
+
     # Usernames can't be shorter than minlen
+
     if len(username) < minlen:
+
         return False
-    # Usernames can only use letters, numbers, dots and underscores
-    if not re.match('^[a-z0-9._]*$', username):
+
+    # Usernames can only use letters, numbers, dots and underscores, and cannot start with . or _
+
+    if not re.match('^[a-z0-9][a-z0-9._]*$', username):  # Changed regex here
+
         return False
-    # Usernames can't begin with a number
+
+    # Usernames can't begin with a number (this check is now redundant but kept for clarity)
+
     if username[0].isnumeric():
+
         return False
+
     return True
 
 
+print(validate_user("blue.kale", 3)) # True
+
+print(validate_user(".blue.kale", 3)) # Now False
+
+print(validate_user("red_quinoa", 4)) # True
+
+print(validate_user("_red_quinoa", 4)) # Now False
+
+print(validate_user("1red_quinoa", 4)) # False (still works)
+
+print(validate_user("!blue.kale", 3)) # False
+
+print(validate_user("bl?ue.kale", 3)) # False