device test for #4516 (WiFiClient leaking) (#4549)

* device test for #4516 (WiFiClient leaking)

* simply count the number of connections that do not change heap

* remove unused heapLost

* + python server (to not depend on gateway's opened tcp port)

* remove old&bad define

* fix another old address

tests/device/test_ClientContext/test_ClientContext.py

@@ -0,0 +1,60 @@
+from mock_decorators import setup, teardown
+from flask import Flask, request
+from threading import Thread
+import socket
+import select
+import sys
+import os
+
+@setup('WiFi release ClientContext')
+def setup_tcpsrv(e):
+
+    global thread
+
+    app = Flask(__name__)
+
+    def run():
+
+        global running
+
+        running = False
+        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        for port in range(8266, 8285 + 1):
+            try:
+                print >>sys.stderr, 'trying port', port
+                server_address = ("0.0.0.0", port)
+                sock.bind(server_address)
+                sock.listen(1)
+                running = True
+                break
+            except Exception:
+                print >>sys.stderr, 'busy'
+        if not running:
+            return
+        print >>sys.stderr, 'starting up on %s port %s' % server_address
+        print >>sys.stderr, 'waiting for connections'
+        while running:
+            print >>sys.stderr, 'loop'
+            readable, writable, errored = select.select([sock], [], [], 1.0)
+            if readable:
+                connection, client_address = sock.accept()
+                try:
+                    print >>sys.stderr, 'client connected:', client_address
+                finally:
+                    print >>sys.stderr, 'close'
+                    connection.shutdown(socket.SHUT_RDWR)
+                    connection.close()
+
+    thread = Thread(target=run)
+    thread.start()
+
+@teardown('WiFi release ClientContext')
+def teardown_tcpsrv(e):
+    
+    global thread
+    global running
+    
+    print >>sys.stderr, 'closing'
+    running = False
+    thread.join()
+    return 0