uasyncio: Add echo test

uasyncio/test_echo.py

@@ -0,0 +1,32 @@
+from uasyncio import get_event_loop, open_connection, start_server, sleep_ms
+from unittest import main, TestCase
+
+class EchoTestCase(TestCase):
+
+    def test_client_server(self):
+        '''Simple client-server echo test'''
+        sockaddr = ('127.0.0.1', 8080)
+        l = get_event_loop()
+
+        async def echo_server(reader, writer):
+            data = await reader.readline()
+            await writer.awrite(data)
+            await writer.aclose()
+
+        async def echo_client(line, result):
+            await sleep_ms(10)  # Allow server to get up
+            reader, writer = await open_connection(*sockaddr)
+            await writer.awrite(line)
+            data = await reader.readline()
+            await writer.aclose()
+            result.append(data)  # capture response
+
+        result = []
+        l.create_task(start_server(echo_server, *sockaddr))
+        l.run_until_complete(echo_client(b'Hello\r\n', result))
+
+        self.assertEqual(result[0], b'Hello\r\n')
+
+
+if __name__ == '__main__':
+    main()