1 files changed, 30 insertions, 2 deletions
diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index 22f81e55b56..4ca7062961a 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -204,6 +204,33 @@ def _set_signature(mock, original, instance=False):
     _setup_func(funcopy, mock, sig)
     return funcopy
 
+def _set_async_signature(mock, original, instance=False, is_async_mock=False):
+    # creates an async function with signature (*args, **kwargs) that delegates to a
+    # mock. It still does signature checking by calling a lambda with the same
+    # signature as the original.
+
+    skipfirst = isinstance(original, type)
+    result = _get_signature_object(original, instance, skipfirst)
+    if result is None:
+        return mock
+    func, sig = result
+    def checksig(*args, **kwargs):
+        sig.bind(*args, **kwargs)
+    _copy_func_details(func, checksig)
+
+    name = original.__name__
+    if not name.isidentifier():
+        name = 'funcopy'
+    context = {'_checksig_': checksig, 'mock': mock}
+    src = """async def %s(*args, **kwargs):
+    _checksig_(*args, **kwargs)
+    return await mock(*args, **kwargs)""" % name
+    exec (src, context)
+    funcopy = context[name]
+    _setup_func(funcopy, mock, sig)
+    _setup_async_mock(funcopy)
+    return funcopy
+
 
 def _setup_func(funcopy, mock, sig):
     funcopy.mock = mock
@@ -2745,9 +2772,10 @@ def create_autospec(spec, spec_set=False, instance=False, _parent=None,
     if isinstance(spec, FunctionTypes):
         # should only happen at the top level because we don't
         # recurse for functions
-        mock = _set_signature(mock, spec)
         if is_async_func:
-            _setup_async_mock(mock)
+            mock = _set_async_signature(mock, spec)
+        else:
+            mock = _set_signature(mock, spec)
     else:
         _check_signature(spec, mock, is_type, instance)