Add absolute path check for filename validation

Author: thombashi

pathvalidate/_file.py

@@ -223,6 +223,8 @@ def validate(self, value: PathType) -> None:
         unicode_filename = preprocess(value)
         value_len = len(unicode_filename)
 
+        self.__validate_abspath(unicode_filename)
+
         if value_len > self.max_len:
             raise InvalidLengthError(
                 "filename is too long: expected<={:d}, actual={:d}".format(self.max_len, value_len)
@@ -239,6 +241,14 @@ def validate(self, value: PathType) -> None:
         else:
             self.__validate_unix_filename(unicode_filename)
 
+    def __validate_abspath(self, value: str) -> None:
+        if any([ntpath.isabs(value), posixpath.isabs(value)]):
+            raise ValidationError(
+                description="found an absolute path ({}), expected a filename".format(value),
+                platform=self.platform,
+                reason=ErrorReason.FOUND_ABS_PATH,
+            )
+
     def __validate_unix_filename(self, unicode_filename: str) -> None:
         match = self.__RE_INVALID_FILENAME.findall(unicode_filename)
         if match:

test/test_filename.py

@@ -11,11 +11,13 @@
 import pytest
 
 from pathvalidate import (
+    ErrorReason,
     InvalidCharError,
     InvalidLengthError,
     NullNameError,
     Platform,
     ReservedNameError,
+    ValidationError,
     is_valid_filename,
     sanitize_filename,
     validate_filename,
@@ -281,8 +283,9 @@ def test_exception_reserved_name(self, value, platform, expected):
         ],
     )
     def test_exception_filepath(self, value, platform):
-        with pytest.raises(InvalidCharError):
+        with pytest.raises(ValidationError) as e:
             validate_filename(value, platform=platform)
+        assert e.value.reason in [ErrorReason.FOUND_ABS_PATH, ErrorReason.INVALID_CHARACTER]
         assert not is_valid_filename(value, platform=platform)
 
     @pytest.mark.parametrize(