improved is_email + more tests

Author: daveoncode

string_utils/validation.py

@@ -234,26 +234,22 @@ def is_email(input_string: Any) -> bool:
         # we expect 2 tokens, one before "@" and one after, otherwise we have an exception and the email is not valid
         head, tail = input_string.split('@')
 
+        # head's size must be <= 64, tail <= 255, head must not start with a dot or contain multiple consecutive dots
+        if len(head) > 64 or len(tail) > 255 or head.endswith('.') or ('..' in head):
+            return False
+
         # removes escaped spaces, so that later on the test regex will accept the string
         head = head.replace('\\ ', '')
         if head.startswith('"') and head.endswith('"'):
             head = head.replace(' ', '')[1:-1]
 
-        if head.endswith('.') or len(head) > 64 or len(tail) > 255:
-            return False
-
-        # multiple consecutive dots are forbidden
-        if '..' in head:
-            return False
-
         return EMAIL_RE.match(head + '@' + tail) is not None
 
     except ValueError:
         # borderline case in which we have multiple "@" signs but the head part is correctly escaped
         if ESCAPED_AT_SIGN.search(input_string) is not None:
             # replace "@" with "a" in the head
-            sanitized = ESCAPED_AT_SIGN.sub('a', input_string)
-            return is_email(sanitized)
+            return is_email(ESCAPED_AT_SIGN.sub('a', input_string))
 
         return False
 

tests/test_is_email.py

@@ -4,6 +4,13 @@
 
 
 class IsEmailTestCase(TestCase):
+    """
+    Definitions:
+
+    "head" -> the part before "@"
+    "tail" -> the part after "@"
+    """
+
     def test_should_return_false_for_non_string_objects(self):
         # noinspection PyTypeChecker
         self.assertFalse(is_email(None))
@@ -24,10 +31,10 @@ def test_string_cannot_be_empty(self):
         self.assertFalse(is_email(''))
         self.assertFalse(is_email(' '))
 
-    def test_domain_part_is_required(self):
+    def test_tail_is_required(self):
         self.assertFalse(is_email('name@'))
 
-    def test_name_part_is_required(self):
+    def test_head_is_required(self):
         self.assertFalse(is_email('@foo.com'))
 
     def test_at_sign_is_required(self):
@@ -44,19 +51,19 @@ def test_domain_extension_should_be_letters_only_from_2_to_4_chars(self):
         self.assertFalse(is_email('me@foo.___'))
         self.assertFalse(is_email('[email protected]'))
 
-    def test_name_part_cannot_contain_suqare_brackets(self):
+    def test_head_cannot_contain_suqare_brackets(self):
         self.assertFalse(is_email('[[email protected]'))
         self.assertFalse(is_email('my][email protected]'))
 
-    def test_domain_part_cannot_contain_bad_signs(self):
+    def test_tail_cannot_contain_bad_signs(self):
         self.assertFalse(is_email('me@#foo#.com'))
         self.assertFalse(is_email('me@foo!.com'))
         self.assertFalse(is_email('someone@[foo].com'))
 
-    def test_domain_part_cannot_be_uppercase(self):
+    def test_tail_cannot_be_uppercase(self):
         self.assertFalse(is_email('[email protected]'))
 
-    def test_domain_part_cannot_contain_dots_sequence(self):
+    def test_tail_cannot_contain_dots_sequence(self):
         self.assertFalse(is_email('[email protected]'))
         self.assertFalse(is_email('[email protected]'))
 
@@ -77,79 +84,124 @@ def test_max_email_length_is_respected(self):
         invalid_email = ('a' * 320) + '@gmail.com'
         self.assertFalse(is_email(invalid_email))
 
-    def test_local_part_length_is_respected(self):
-        # max local part is 64 (before "@")
+    def test_head_length_is_respected(self):
+        # max head size is 64
         invalid_email = ('a' * 65) + '@gmail.com'
         self.assertFalse(is_email(invalid_email))
 
-    def test_octects_part_length_is_respected(self):
-        # max octets part is 255 (after "@")
+    def test_tail_length_is_respected(self):
+        # max tail size is 255
         invalid_email = 'a@{}.com'.format(255 * 'x')
         self.assertFalse(is_email(invalid_email))
 
-    def test_plus_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("[email protected]"))
+    def test_plus_is_valid_char_in_head(self):
+        self.assertTrue(is_email('[email protected]'))
+
+    def test_plus_is_invalid_char_in_tail(self):
+        self.assertFalse(is_email('mymail@foo+bar.com'))
+
+    def test_minus_is_valid_char_in_head(self):
+        self.assertTrue(is_email('[email protected]'))
+
+    def test_slash_is_valid_char_in_head(self):
+        self.assertTrue(is_email('my/[email protected]'))
+
+    def test_slash_is_invalid_char_in_tail(self):
+        self.assertFalse(is_email('mymail@foo/bar.com'))
+
+    def test_back_slash_is_valid_char_in_head(self):
+        self.assertTrue(is_email('my\\[email protected]'))
+
+    def test_equal_is_valid_char_in_head(self):
+        self.assertTrue(is_email('[email protected]'))
+
+    def test_equal_is_invalid_char_in_tail(self):
+        self.assertFalse(is_email('mymail@gm=ail.com'))
 
-    def test_minus_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my-[email protected]"))
+    def test_question_mark_is_valid_char_in_head(self):
+        self.assertTrue(is_email('my?[email protected]'))
 
-    def test_slash_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my/mail@gmail.com"))
+    def test_question_mark_is_invalid_char_in_tail(self):
+        self.assertFalse(is_email('mymail@gm?ail.com'))
 
-    def test_back_slash_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my\\[email protected]"))
+    def test_sharp_is_valid_char_in_head(self):
+        self.assertTrue(is_email('my#[email protected]'))
 
-    def test_equal_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my=mail@gmail.com"))
+    def test_sharp_is_invalid_char_in_tail(self):
+        self.assertFalse(is_email('mymail@gma#il.com'))
 
-    def test_question_mark_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my?[email protected]"))
+    def test_dollar_is_valid_char_in_head(self):
+        self.assertTrue(is_email('my$[email protected]'))
 
-    def test_sharp_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my#mail@gmail.com"))
+    def test_dollar_is_invalid_char_in_tail(self):
+        self.assertFalse(is_email('mymail@gm$ail.com'))
 
-    def test_dollar_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my$[email protected]"))
+    def test_and_is_valid_char_in_head(self):
+        self.assertTrue(is_email('my&[email protected]'))
 
-    def test_and_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my&mail@gmail.com"))
+    def test_and_is_invalid_char_in_tail(self):
+        self.assertFalse(is_email('mymail@gm&ail.com'))
 
-    def test_asterisk_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my*[email protected]"))
+    def test_asterisk_is_valid_char_in_head(self):
+        self.assertTrue(is_email('my*[email protected]'))
 
-    def test_apostrophe_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my'mail@gmail.com"))
+    def test_asterisk_is_invalid_char_in_tail(self):
+        self.assertFalse(is_email('mymail@gmai*l.com'))
 
-    def test_acute_accent_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my`[email protected]"))
+    def test_apostrophe_is_valid_char_in_head(self):
+        self.assertTrue(is_email('my\'[email protected]'))
 
-    def test_percentage_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my%mail@gmail.com"))
+    def test_apostrophe_is_invalid_char_in_tail(self):
+        self.assertFalse(is_email('mymail@gma\'il.com'))
 
-    def test_exclamation_mark_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my![email protected]"))
+    def test_acute_accent_is_valid_char_in_head(self):
+        self.assertTrue(is_email('my`[email protected]'))
 
-    def test_caret_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my^mail@gmail.com"))
+    def test_acute_accent_is_invalid_char_in_tail(self):
+        self.assertFalse(is_email('mymail@gma`il.com'))
 
-    def test_pipe_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my|[email protected]"))
+    def test_percentage_is_valid_char_in_head(self):
+        self.assertTrue(is_email('my%[email protected]'))
 
-    def test_tilde_is_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my~mail@gmail.com"))
+    def test_percentage_is_invalid_char_in_tail(self):
+        self.assertFalse(is_email('mymail@gma%il.com'))
 
-    def test_curly_braces_are_valid_char_in_local_part(self):
-        self.assertTrue(is_email("my{[email protected]"))
-        self.assertTrue(is_email("my}[email protected]"))
-        self.assertTrue(is_email("{mymail}@gmail.com"))
+    def test_exclamation_mark_is_valid_char_in_head(self):
+        self.assertTrue(is_email('[email protected]'))
 
-    def test_local_part_cannot_start_with_period(self):
+    def test_exclamation_mark_is_invalid_char_in_tail(self):
+        self.assertFalse(is_email('mymail@gm!ail.com'))
+
+    def test_caret_is_valid_char_in_head(self):
+        self.assertTrue(is_email('my^[email protected]'))
+
+    def test_caret_is_invalid_char_in_tail(self):
+        self.assertFalse(is_email('mymail@gma^il.com'))
+
+    def test_pipe_is_valid_char_in_head(self):
+        self.assertTrue(is_email('my|[email protected]'))
+
+    def test_pipe_is_invalid_char_in_tail(self):
+        self.assertFalse(is_email('mymail@gm|ail.com'))
+
+    def test_tilde_is_valid_char_in_head(self):
+        self.assertTrue(is_email('[email protected]'))
+
+    def test_tilde_is_invalid_char_in_tail(self):
+        self.assertFalse(is_email('mymail@gma~il.com'))
+
+    def test_curly_braces_are_valid_char_in_head(self):
+        self.assertTrue(is_email('my{[email protected]'))
+        self.assertTrue(is_email('my}[email protected]'))
+        self.assertTrue(is_email('{mymail}@gmail.com'))
+
+    def test_head_cannot_start_with_period(self):
         self.assertFalse(is_email('[email protected]'))
 
-    def test_local_part_cannot_end_with_period(self):
+    def test_head_cannot_end_with_period(self):
         self.assertFalse(is_email('[email protected]'))
 
-    def test_local_part_cannot_have_multiple_consecutive_periods(self):
+    def test_head_cannot_have_multiple_consecutive_periods(self):
         self.assertFalse(is_email('[email protected]'))
         self.assertFalse(is_email('[email protected]'))
 
@@ -158,14 +210,21 @@ def test_empty_spaces_are_allowed_only_if_escaped(self):
         self.assertTrue(is_email('my\\ [email protected]'))
         self.assertTrue(is_email('"my mail"@gmail.com'))
 
-    def test_local_part_can_be_quoted(self):
+    def test_head_can_be_quoted(self):
         self.assertTrue(is_email('"foo"@example.com'))
 
+    def test_head_quotes_must_be_correct(self):
+        self.assertFalse(is_email('"[email protected]'))
+        self.assertFalse(is_email('no"[email protected]'))
+        self.assertFalse(is_email('nope"@gmail.com'))
+        self.assertFalse(is_email('""@gmail.com'))
+        self.assertFalse(is_email('"no"pe"@gmail.com'))
+
     def test_with_quoted_string_multiple_at_are_accepted(self):
         self.assertTrue(is_email('"Abc@def"@example.com'))
 
     def test_with_escape_multiple_at_are_accepted(self):
         self.assertTrue(is_email('Abc\\@[email protected]'))
 
-    def test_local_part_can_have_self_escape(self):
+    def test_head_can_have_self_escape(self):
         self.assertTrue(is_email('Joe.\\\\[email protected]'))