Merge pull request #299 from twisted/ibodyproducer-files-tuples-length

Improve error message for short/long file tuples

changelog.d/299.feature.rst

@@ -0,0 +1 @@
+treq produces a more helpful exception when passed a tuple of the wrong size in the *files* parameter.

src/treq/client.py

@@ -394,6 +394,18 @@ def _convert_files(files):
                 file_name, fobj = val
             elif len(val) == 3:
                 file_name, content_type, fobj = val
+            else:
+                # NB: This is TypeError for backward compatibility. This case
+                # used to fall through to `IBodyProducer`, below, which raised
+                # TypeError about being unable to coerce None.
+                raise TypeError(
+                    (
+                        "`files` argument must be a sequence of tuples of"
+                        " (file_name, file_obj) or"
+                        " (file_name, content_type, file_obj),"
+                        " but the {!r} tuple has length {}: {!r}"
+                    ).format(param, len(val), val),
+                )
         else:
             fobj = val
             if hasattr(fobj, "name"):
@@ -402,6 +414,7 @@ def _convert_files(files):
         if not content_type:
             content_type = _guess_content_type(file_name)
 
+        # XXX: Shouldn't this call self._data_to_body_producer?
         yield (param, (file_name, content_type, IBodyProducer(fobj)))
 
 

src/treq/test/test_client.py

@@ -398,6 +398,36 @@ def test_request_named_attachment_and_ctype(self):
                 boundary=b'heyDavid'),
             self.MultiPartProducer.call_args)
 
+    def test_request_files_tuple_too_short(self):
+        """
+        The `HTTPClient.request()` *files* argument requires tuples of length
+        2 or 3. It raises `TypeError` when the tuple is too short.
+        """
+        with self.assertRaises(TypeError) as c:
+            self.client.request(
+                "POST",
+                b"http://example.com/",
+                files=[("t1", ("foo.txt",))],
+            )
+
+        self.assertIn("'t1' tuple has length 1", str(c.exception))
+
+    def test_request_files_tuple_too_long(self):
+        """
+        The `HTTPClient.request()` *files* argument requires tuples of length
+        2 or 3. It raises `TypeError` when the tuple is too long.
+        """
+        with self.assertRaises(TypeError) as c:
+            self.client.request(
+                "POST",
+                b"http://example.com/",
+                files=[
+                    ("t4", ("foo.txt", "text/plain", BytesIO(b"...\n"), "extra!")),
+                ],
+            )
+
+        self.assertIn("'t4' tuple has length 4", str(c.exception))
+
     @mock.patch('treq.client.uuid.uuid4', mock.Mock(return_value="heyDavid"))
     def test_request_mixed_params(self):