test: Improve test coverage to 100%

multipart.py

@@ -639,7 +639,7 @@ def __init__(self):
         self._complete = False
 
     def _append(self, data):
-        if self._size < 0:
+        if self._size < 0:  # pragma: no cover
             raise RuntimeError("Invalid state")
         self._size += len(data)
         self._buffer += data

test/test_push_parser.py

@@ -162,3 +162,25 @@ def test_header_bad_name(self):
         self.reset()
         with self.assertMPE("Malformed header: Empty name"):
             self.parse(b"--boundary\r\n:just-value\r\n\r\ndata\r\n--boundary--")
+
+    def test_partial_parts(self):
+        self.reset()
+        self.assertEqual([], self.parse(b'--boundary\r\n'))
+        self.assertEqual([], self.parse(b'Header: value\r\n'))
+        self.assertEqual([], self.parse(b'\r\n'))
+        # Write enough body data to trigger a new part
+        part = self.parse(b'body'*10)[0]
+        self.assertTrue(part.incomplete)
+        self.assertFalse(part.complete)
+        self.assertTrue(part.buffersize > 0)
+        self.assertEqual(part.size, part.buffersize)
+        part.drain()
+        self.assertEqual(0, part.buffersize)
+        # Write partial boundary, should stay incomplete
+        self.assertEqual([part], self.parse(b'\r\n--boundary'))
+        self.assertTrue(part.incomplete)
+        self.assertTrue(part.buffersize > 0)
+        # Turn the incomplete boundary into a terminator
+        self.assertEqual([part], self.parse(b'--'))
+        self.assertTrue(part.complete)
+        self.assertEqual(40, part.size)