Add number of bytes to stream.read_nowait

aiohttp/streams.py

@@ -297,15 +297,15 @@ def readexactly(self, n):
 
         return b''.join(blocks)
 
-    def read_nowait(self):
+    def read_nowait(self, n=None):
         if self._exception is not None:
             raise self._exception
 
         if self._waiter and not self._waiter.done():
             raise RuntimeError(
                 'Called while some coroutine is waiting for incoming data.')
 
-        return self._read_nowait()
+        return self._read_nowait(n)
 
     def _read_nowait(self, n=None):
         if not self._buffer:

tests/test_streams.py

@@ -452,6 +452,20 @@ def test_read_nowait(self):
         data = self.loop.run_until_complete(stream.read())
         self.assertEqual(b'', data)
 
+    def test_read_nowait_n(self):
+        stream = self._make_one()
+        stream.feed_data(b'line1\nline2\n')
+
+        self.assertEqual(
+            stream.read_nowait(4), b'line')
+        self.assertEqual(
+            stream.read_nowait(), b'1\nline2\n')
+        self.assertIs(
+            stream.read_nowait(), streams.EOF_MARKER)
+        stream.feed_eof()
+        data = self.loop.run_until_complete(stream.read())
+        self.assertEqual(b'', data)
+
     def test_read_nowait_exception(self):
         stream = self._make_one()
         stream.feed_data(b'line\n')