add getfullargspec() for python3 (#701)

Author: wallacbe

openhtf/__init__.py

@@ -525,10 +525,16 @@ def __call__(self, test_state):
     kwargs = dict(self.extra_kwargs)
     kwargs.update(test_state.plug_manager.provide_plugs(
         (plug.name, plug.cls) for plug in self.plugs if plug.update_kwargs))
-    arg_info = inspect.getargspec(self.func)
+
+    if sys.version_info[0] < 3:
+      arg_info = inspect.getargspec(self.func)
+      keywords = arg_info.keywords
+    else:
+      arg_info = inspect.getfullargspec(self.func)
+      keywords = arg_info.varkw
     # Pass in test_api if the phase takes *args, or **kwargs with at least 1
     # positional, or more positional args than we have keyword args.
-    if arg_info.varargs or (arg_info.keywords and len(arg_info.args) >= 1) or (
+    if arg_info.varargs or (keywords and len(arg_info.args) >= 1) or (
         len(arg_info.args) > len(kwargs)):
       # Underlying function has room for test_api as an arg. If it doesn't
       # expect it but we miscounted args, we'll get another error farther down.