feat(content-type): add warning if a pac file is found but the content-type is invalid

pypac/api.py

@@ -2,6 +2,7 @@
 These are the most commonly used components of PyPAC.
 """
 import os
+import logging
 from contextlib import contextmanager
 
 import requests
@@ -18,6 +19,7 @@
 )
 from pypac.wpad import proxy_urls_from_dns
 
+logger = logging.getLogger(__name__)
 
 def get_pac(
     url=None,
@@ -157,6 +159,9 @@ def download_pac(candidate_urls, timeout=1, allowed_content_types=None, session=
             resp = sess.get(pac_url, timeout=timeout)
             content_type = resp.headers.get("content-type", "").lower()
             if content_type and True not in [allowed_type in content_type for allowed_type in allowed_content_types]:
+                logger.warning(
+                    f"{pac_url} available but content-type {content_type} is not allowed. Only {','.join(allowed_content_types)} are allowed."
+                )
                 continue
             if resp.ok:
                 return resp.text

tests/test_api.py

@@ -1,3 +1,4 @@
+import logging
 import os
 import sys
 
@@ -78,12 +79,17 @@ def test_download_pac_not_ok(self):
             ({"content-type": "text/plain"}, ["text/plain"], direct_pac_js),
         ],
     )
-    def test_download_pac_content_type(self, headers, allowed_content_types, expected_value):
+    def test_download_pac_content_type(self, headers, allowed_content_types, expected_value, caplog):
         """Test acceptance/rejection of obtained PAC based on Content-Type header."""
         mock_pac_response = Mock(spec=requests.Response, ok=True, headers=headers, text=direct_pac_js)
         with _patch_request_base(mock_pac_response):
             result = download_pac([arbitrary_pac_url], allowed_content_types=allowed_content_types)
             assert result == expected_value
+        if expected_value is None:
+            ex_warn = "available but content-type {} is not allowed".format(headers["content-type"])
+            log = caplog.records[0]
+            assert log.levelno == logging.WARNING
+            assert ex_warn in log.msg
 
     def test_registry_filesystem_path(self):
         """