Implemented tasklets.synctasklet (#58)

* Implemented tasklets.synctasklet

Author: chenyumic

packages/google-cloud-ndb/src/google/cloud/ndb/tasklets.py

@@ -502,8 +502,23 @@ def set_context(*args, **kwargs):
     raise NotImplementedError
 
 
-def synctasklet(*args, **kwargs):
-    raise NotImplementedError
+def synctasklet(wrapped):
+    """A decorator to run a tasklet as a function when called.
+
+    Use this to wrap a request handler function that will be called by some
+    web application framework (e.g. a Django view function or a
+    webapp.RequestHandler.get method).
+
+    Args:
+        wrapped (callable): The wrapped function.
+    """
+    taskletfunc = tasklet(wrapped)
+
+    @functools.wraps(wrapped)
+    def synctasklet_wrapper(*args, **kwargs):
+        return taskletfunc(*args, **kwargs).result()
+
+    return synctasklet_wrapper
 
 
 def toplevel(*args, **kwargs):

packages/google-cloud-ndb/tests/unit/test_tasklets.py

@@ -593,9 +593,17 @@ def test_set_context():
         tasklets.set_context()
 
 
+@pytest.mark.usefixtures("in_context")
 def test_synctasklet():
-    with pytest.raises(NotImplementedError):
-        tasklets.synctasklet()
+    @tasklets.synctasklet
+    def generator_function(value):
+        future = tasklets.Future(value)
+        future.set_result(value)
+        x = yield future
+        return x + 3
+
+    result = generator_function(8)
+    assert result == 11
 
 
 def test_toplevel():