add fileno test

Author: Wauplin

tests/test_commit_scheduler.py

@@ -206,13 +206,22 @@ def test_read_partial_file_too_much(self) -> None:
         self.assertEqual(file.read(20), b"12345")
 
     def test_partial_file_len(self) -> None:
-        """Useful for `requests` internally."""
+        """Useful for httpx internally."""
         file = PartialFileIO(self.file_path, size_limit=5)
         self.assertEqual(len(file), 5)
 
         file = PartialFileIO(self.file_path, size_limit=50)
         self.assertEqual(len(file), 9)
 
+    def test_partial_file_fileno(self) -> None:
+        """We explicitly do not implement fileno() to avoid misuse.
+
+        httpx tries to use it to check file size which we don't want for PartialFileIO.
+        """
+        file = PartialFileIO(self.file_path, size_limit=5)
+        with self.assertRaises(AttributeError):
+            file.fileno()
+
     def test_partial_file_seek_and_tell(self) -> None:
         file = PartialFileIO(self.file_path, size_limit=5)