tests/net_hosted/asyncio_loopback.py: Add loopback test.

Signed-off-by: Peter Züger <zueger.peter@icloud.com>

tests/net_hosted/asyncio_loopback.py

@@ -0,0 +1,64 @@
+# Test network loopback behaviour
+
+try:
+    import asyncio
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+
+async def client(host, port):
+    print(f"client open_connection to {host}:{port}")
+    reader, writer = await asyncio.open_connection(host, port)
+
+    data_in = b"A" * 100
+
+    print("client writing")
+    writer.write(data_in)
+    await writer.drain()
+
+    await asyncio.sleep(0.1)
+
+    print("client reading")
+    data = await reader.readexactly(100)
+    print(f"client got {len(data)} bytes")
+
+    assert data_in == data
+
+    print("client closing")
+
+    writer.close()
+    await writer.wait_closed()
+
+    print("client closed")
+
+
+async def echo_handler(reader, writer):
+    print("handler reading")
+    await asyncio.sleep(0.1)
+    data = await reader.readexactly(100)
+    print(f"handler got {len(data)} bytes")
+
+    print("handler writing")
+    writer.write(data)
+    await writer.drain()
+
+    print("handler closing")
+
+    writer.close()
+    await writer.wait_closed()
+
+    print("handler closed")
+
+
+async def test(host, port):
+    print(f"create server on {host}:{port}")
+    server = await asyncio.start_server(echo_handler, host, port)
+
+    async with server:
+        print("server started")
+        await client("127.0.0.1", 8080)
+    print("server closed")
+
+
+asyncio.run(test("0.0.0.0", 8080))

tests/net_hosted/asyncio_loopback.py.exp

@@ -0,0 +1,14 @@
+create server on 0.0.0.0:8080
+server started
+client open_connection to 127.0.0.1:8080
+client writing
+handler reading
+client reading
+handler got 100 bytes
+handler writing
+handler closing
+handler closed
+client got 100 bytes
+client closing
+client closed
+server closed