maint: improves domain module

- Uses type hints, improve docs
- Regards [RFC 1035](https://www.rfc-editor.org/rfc/rfc1035)
- Updates corresponding test functions
- Closes python-validators#74, python-validators#81, python-validators#89, python-validators#124, python-validators#143, & python-validators#204

tests/test_domain.py

@@ -1,42 +1,54 @@
+"""Test Domain."""
 # -*- coding: utf-8 -*-
+
+# standard
 import pytest
 
+# local
 from validators import domain, ValidationFailure
 
 
-@pytest.mark.parametrize('value', [
-    'example.com',
-    'xn----gtbspbbmkef.xn--p1ai',
-    'underscore_subdomain.example.com',
-    'something.versicherung',
-    'someThing.versicherung',
-    '11.com',
-    '3.cn',
-    'a.cn',
-    'sub1.sub2.sample.co.uk',
-    'somerandomexample.xn--fiqs8s',
-    'kräuter.com',
-    'über.com'
-])
-def test_returns_true_on_valid_domain(value):
-    assert domain(value)
+@pytest.mark.parametrize(
+    ("value", "trailing_dot"),
+    [
+        ("example.com", False),
+        ("xn----gtbspbbmkef.xn--p1ai", False),
+        ("underscore_subdomain.example.com", False),
+        ("something.versicherung", False),
+        ("someThing.versicherung.", True),
+        ("11.com", False),
+        ("3.cn.", True),
+        ("a.cn", False),
+        ("sub1.sub2.sample.co.uk", False),
+        ("somerandomexample.xn--fiqs8s", False),
+        ("kräuter.com.", True),
+        ("über.com", False),
+    ],
+)
+def test_returns_true_on_valid_domain(value: str, trailing_dot: bool):
+    """Test returns true on valid domain."""
+    assert domain(value, trailing_dot=trailing_dot)
 
 
-@pytest.mark.parametrize('value', [
-    'example.com/',
-    'example.com:4444',
-    'example.-com',
-    'example.',
-    '-example.com',
-    'example-.com',
-    '_example.com',
-    'example_.com',
-    'example',
-    'a......b.com',
-    'a.123',
-    '123.123',
-    '123.123.123',
-    '123.123.123.123'
-])
-def test_returns_failed_validation_on_invalid_domain(value):
-    assert isinstance(domain(value), ValidationFailure)
+@pytest.mark.parametrize(
+    ("value", "trailing_dot"),
+    [
+        ("example.com/.", True),
+        ("example.com:4444", False),
+        ("example.-com", False),
+        ("example.", False),
+        ("-example.com", False),
+        ("example-.com.", True),
+        ("_example.com", False),
+        ("example_.com", False),
+        ("example", False),
+        ("a......b.com", False),
+        ("a.123", False),
+        ("123.123", False),
+        ("123.123.123.", True),
+        ("123.123.123.123", False),
+    ],
+)
+def test_returns_failed_validation_on_invalid_domain(value: str, trailing_dot: bool):
+    """Test returns failed validation on invalid domain."""
+    assert isinstance(domain(value, trailing_dot=trailing_dot), ValidationFailure)

validators/domain.py

@@ -1,54 +1,51 @@
+"""Domain."""
+
+# standard
 import re
 
+# local
 from .utils import validator
 
-pattern = re.compile(
-    r'^(?:[a-zA-Z0-9]'  # First character of the domain
-    r'(?:[a-zA-Z0-9-_]{0,61}[A-Za-z0-9])?\.)'  # Sub domain + hostname
-    r'+[A-Za-z0-9][A-Za-z0-9-_]{0,61}'  # First 61 characters of the gTLD
-    r'[A-Za-z]$'  # Last character of the gTLD
-)
-
-
-def to_unicode(obj, charset='utf-8', errors='strict'):
-    if obj is None:
-        return None
-    if not isinstance(obj, bytes):
-        return str(obj)
-    return obj.decode(charset, errors)
-
 
 @validator
-def domain(value):
-    """
-    Return whether or not given value is a valid domain.
-
-    If the value is valid domain name this function returns ``True``, otherwise
-    :class:`~validators.utils.ValidationFailure`.
-
-    Examples::
+def domain(value: str, /, *, trailing_dot: bool = False):
+    """Return whether or not given value is a valid domain.
 
+    Examples:
         >>> domain('example.com')
-        True
-
+        # Output: True
         >>> domain('example.com/')
-        ValidationFailure(func=domain, ...)
-
-
-    Supports IDN domains as well::
-
+        # Output: ValidationFailure(func=domain, ...)
+        >>> # Supports IDN domains as well::
         >>> domain('xn----gtbspbbmkef.xn--p1ai')
-        True
+        # Output: True
+
+    Args:
+        value:
+            Domain string to validate.
+        trailing_dots:
+            Optional parameter for RFC 1035
 
-    .. versionadded:: 0.9
 
-    .. versionchanged:: 0.10
+    Returns:
+        (Literal[True]):
+            If `value` is a valid domain name.
+        (ValidationFailure):
+            If `value` is an invalid domain name.
 
-        Added support for internationalized domain name (IDN) validation.
+    Note:
+        - *In version 0.10.0*:
+            - Added support for internationalized domain name (IDN) validation.
 
-    :param value: domain string to validate
+    > *New in version 0.9.0*.
     """
     try:
-        return pattern.match(to_unicode(value).encode('idna').decode('ascii'))
-    except (UnicodeError, AttributeError):
+        return not re.search(r"\s", value) and re.compile(
+            r"^(?:[a-zA-Z0-9]"  # First character of the domain
+            + r"(?:[a-zA-Z0-9-_]{0,61}[A-Za-z0-9])?\.)"  # Sub domain + hostname
+            + r"+[A-Za-z0-9][A-Za-z0-9-_]{0,61}"  # First 61 characters of the gTLD
+            + r"[A-Za-z]"  # Last character of the gTLD
+            + (r".$" if trailing_dot else r"$")
+        ).match(value.encode("idna").decode("ascii"))
+    except UnicodeError:
         return False