tests/run-multitests.py: Set HOST_IP so tests work between PC and board.

Signed-off-by: Damien George <damien@micropython.org>

tests/run-multitests.py

@@ -66,7 +66,7 @@ class multitest:
             import network
             ip = network.WLAN().ifconfig()[0]
         except:
-            ip = "127.0.0.1"
+            ip = HOST_IP
         return ip
 
 {}
@@ -87,6 +87,20 @@ IGNORE_OUTPUT_MATCHES = (
 )
 
 
+def get_host_ip(_ip_cache=[]):
+    if not _ip_cache:
+        try:
+            import socket
+
+            s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+            s.connect(("8.8.8.8", 80))
+            _ip_cache.append(s.getsockname()[0])
+            s.close()
+        except:
+            _ip_cache.append("127.0.0.1")
+    return _ip_cache[0]
+
+
 class PyInstance:
     def __init__(self):
         pass
@@ -274,6 +288,13 @@ def run_test_on_instances(test_file, num_instances, instances):
     injected_globals = ""
     output = [[] for _ in range(num_instances)]
 
+    # If the test calls get_network_ip() then inject HOST_IP so that devices can know
+    # the IP address of the host.  Do this lazily to not require a TCP/IP connection
+    # on the host if it's not needed.
+    with open(test_file, "rb") as f:
+        if b"get_network_ip" in f.read():
+            injected_globals += "HOST_IP = '" + get_host_ip() + "'\n"
+
     if cmd_args.trace_output:
         print("TRACE {}:".format("|".join(str(i) for i in instances)))