Fix error when Stream is closed after container stopped (#608)

* Fix error when Stream is closed after container stopped

* Add changelog

CHANGES/608.bugfix

@@ -0,0 +1 @@
+Fix an error when attach/exec when container stops before close connection to it.

aiodocker/stream.py

@@ -115,7 +115,7 @@ async def close(self) -> None:
             return
         self._closed = True
         transport = self._resp.connection.transport
-        if transport.can_write_eof():
+        if transport and transport.can_write_eof():
             transport.write_eof()
         self._resp.close()
 

tests/test_integration.py

@@ -228,6 +228,30 @@ async def test_attach_nontty(docker, image_name, make_container, stderr):
         assert data.strip() == b"Hello"
 
 
+@pytest.mark.asyncio
+async def test_attach_nontty_wait_for_exit(docker, image_name, make_container):
+    cmd = ["python", "-c", "import time; time.sleep(3); print('Hello')"]
+
+    config = {
+        "Cmd": cmd,
+        "Image": image_name,
+        "AttachStdin": False,
+        "AttachStdout": False,
+        "AttachStderr": False,
+        "Tty": False,
+        "OpenStdin": False,
+        "StdinOnce": False,
+    }
+
+    container = await make_container(
+        config,
+        name="aiodocker-testing-attach-nontty-wait-for-exit",
+    )
+
+    async with container.attach(stdin=False, stdout=True, stderr=True):
+        await asyncio.sleep(10)
+
+
 @pytest.mark.asyncio
 async def test_attach_tty(docker, image_name, make_container):
     skip_windows()