Fix issue with IndexError being raised by the StreamReader.iter_chunk…

…s() generator (#2113)

* stream.readchunk: update unit test to reflect expected behavior

* stream.readchunk() bugfix: do not raise IndexError when buffer is empty

* issue #2112: add news fragment to changes and update contributors

* stream.readchunk: add a new unit test and change eof condition

CONTRIBUTORS.txt

@@ -104,6 +104,7 @@ Kirill Klenov
 Kirill Malovitsa
 Kyrylo Perevozchikov
 Lars P. Søndergaard
+Loïc Lajeanne
 Louis-Philippe Huberdeau
 Lu Gong
 Lubomir Gelo

aiohttp/streams.py

@@ -326,7 +326,10 @@ def readchunk(self):
         if not self._buffer and not self._eof:
             yield from self._wait('readchunk')
 
-        return self._read_nowait_chunk(-1)
+        if self._buffer:
+            return self._read_nowait_chunk(-1)
+        else:
+            return b""
 
     @asyncio.coroutine
     def readexactly(self, n):

changes/2112.bugfix

@@ -0,0 +1 @@
+Fix issue with IndexError being raised by the StreamReader.iter_chunks() generator.

tests/test_streams.py

@@ -547,7 +547,6 @@ def test_read_nowait_waiter(self):
         self.assertRaises(RuntimeError, stream.read_nowait)
 
     def test_readchunk(self):
-
         stream = self._make_one()
 
         def cb():
@@ -562,9 +561,21 @@ def cb():
         data = self.loop.run_until_complete(stream.readchunk())
         self.assertEqual(b'chunk2', data)
 
-        data = self.loop.run_until_complete(stream.read())
+        data = self.loop.run_until_complete(stream.readchunk())
         self.assertEqual(b'', data)
 
+    def test_readchunk_wait_eof(self):
+        stream = self._make_one()
+
+        def cb():
+            yield from asyncio.sleep(0.1, loop=self.loop)
+            stream.feed_eof()
+
+        asyncio.Task(cb(), loop=self.loop)
+        data = self.loop.run_until_complete(stream.readchunk())
+        self.assertEqual(b"", data)
+        self.assertTrue(stream.is_eof())
+
     def test___repr__(self):
         stream = self._make_one()
         self.assertEqual("<StreamReader>", repr(stream))