test: refactor concurrency test using orchestrate

Towards googleapis#691

google/cloud/ndb/_cache.py

@@ -34,6 +34,14 @@
 log = logging.getLogger(__name__)
 
 
+def _syncpoint_692():
+    """A no-op function meant to be patched for testing.
+
+    Should be replaced by `orchestrate.syncpoint` using `mock.patch` during testing to
+    orchestrate concurrent testing scenarios.
+    """
+
+
 class ContextCache(dict):
     """A per-context in-memory entity cache.
 
@@ -684,6 +692,7 @@ def _update_key(key, new_value):
 
         value = new_value(old_value)
         utils.logging_debug(log, "new value: {}", value)
+        _syncpoint_692()
 
         if old_value is not None:
             utils.logging_debug(log, "compare and swap")

tests/conftest.py

@@ -88,22 +88,31 @@ def initialize_environment(request, environ):
 
 
 @pytest.fixture
-def context():
-    client = mock.Mock(
-        project="testing",
-        namespace=None,
-        spec=("project", "namespace"),
-        stub=mock.Mock(spec=()),
-    )
-    context = context_module.Context(
-        client,
-        eventloop=TestingEventLoop(),
-        datastore_policy=True,
-        legacy_data=False,
-    )
+def context_factory():
+    def context(**kwargs):
+        client = mock.Mock(
+            project="testing",
+            namespace=None,
+            spec=("project", "namespace"),
+            stub=mock.Mock(spec=()),
+        )
+        context = context_module.Context(
+            client,
+            eventloop=TestingEventLoop(),
+            datastore_policy=True,
+            legacy_data=False,
+            **kwargs,
+        )
+        return context
+
     return context
 
 
+@pytest.fixture
+def context(context_factory):
+    return context_factory()
+
+
 @pytest.fixture
 def in_context(context):
     assert not context_module._state.context