device tests: some of them can be run on host (#6912)

* device tests: mock scripts + rename some tests to enable mock-testing them

* move symbol

tests/device/test_sw_WiFiServer/test_sw_WiFiServer.py

@@ -0,0 +1,42 @@
+from mock_decorators import setup, teardown
+from threading import Thread
+import socket
+import time
+
+stop_client_thread = False
+client_thread = None
+
+@setup('Simple echo server')
+def setup_echo_server(e):
+    global stop_client_thread
+    global client_thread
+    def echo_client_thread():
+        server_address = socket.gethostbyname('esp8266-wfs-test.local')
+        count = 0
+        while count < 5 and not stop_client_thread:
+            sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+            sock.connect((server_address, 5000))
+            sock.settimeout(1.0)
+            buf = 'a' * 1023 + '\n'
+            sock.sendall(bytes(buf.encode('utf-8')))
+            data = ''
+            retries = 0
+            while len(data) < 1024 and retries < 3:
+                data += sock.recv(1024).decode('utf-8')
+                retries += 1
+            print('Received {} bytes'.format(len(data)))
+            if len(data) != 1024:
+                raise RuntimeError('client failed to receive response')
+            count += 1
+        
+    stop_client_thread = False
+    client_thread = Thread(target=echo_client_thread)
+    client_thread.start()
+
+@teardown('Simple echo server')
+def teardown_echo_server(e):
+    global stop_client_thread
+    stop_client_thread = True
+    client_thread.join()
+
+