Add more tests cases; update changelog

CHANGELOG.rst

@@ -17,7 +17,8 @@ Bug fixes:
 - Correctly handle multiple `@post_load <marshmallow.post_load>` methods where one method appends to
   the data and another passes ``pass_original=True`` (:issue:`1755`).
   Thanks :user:`ghostwheel42` for reporting.
-- ``URL`` fields now properly validate ``file`` paths.
+- ``URL`` fields now properly validate ``file`` paths (:issue:`2249`).
+  Thanks :user:`0xDEC0DE` for reporting and fixing.
 
 Documentation:
 

src/marshmallow/validate.py

@@ -226,9 +226,8 @@ def __call__(self, value: str) -> str:
             relative=self.relative, absolute=self.absolute, require_tld=self.require_tld
         )
 
-        # The `file` scheme is a slightly-special case: hostnames are optional,
-        # and if absent it means `localhost`; fill it in for the validation if
-        # needed
+        # Hostname is optional for file URLS. If absent it means `localhost`.
+        # Fill it in for the validation if needed
         if scheme == "file" and value.startswith("file:///"):
             matched = regex.search(value.replace("file:///", "file://localhost/", 1))
         else:

tests/test_validate.py

@@ -205,11 +205,38 @@ def test_url_custom_scheme():
     assert validator(url) == url
 
 
-def test_url_file_scheme():
-    # Ensure that file URLs don't get confused
-    url = "file:///tmp/tmp1234"
+@pytest.mark.parametrize(
+    "valid_url",
+    (
+        "file:///tmp/tmp1234",
+        "file://localhost/tmp/tmp1234",
+        "file:///C:/Users/test/file.txt",
+        "file://localhost/C:/Program%20Files/file.exe",
+        "file:///home/user/documents/test.pdf",
+        "file:///tmp/test%20file.txt",
+        "file:///",
+        "file://localhost/",
+    ),
+)
+def test_url_accepts_valid_file_urls(valid_url):
     validator = validate.URL(schemes={"file"})
-    assert validator(url) == url
+    assert validator(valid_url) == valid_url
+
+
+@pytest.mark.parametrize(
+    "invalid_url",
+    (
+        "file://",
+        "file:/tmp/file.txt",
+        "file:tmp/file.txt",
+        "file://hostname/path",
+        "file:///tmp/test file.txt",
+    ),
+)
+def test_url_rejects_invalid_file_urls(invalid_url):
+    validator = validate.URL(schemes={"file"})
+    with pytest.raises(ValidationError, match="Not a valid URL."):
+        assert validator(invalid_url)
 
 
 def test_url_relative_and_custom_schemes():