FIX-modin-project#1852: Add stub engines to known ones during test-in…

…ternals (modin-project#1853)

Signed-off-by: Vasilij Litvinov <vasilij.n.litvinov@intel.com>

modin/data_management/test/test_dispatcher.py

@@ -18,6 +18,8 @@
 from modin.data_management.dispatcher import EngineDispatcher, FactoryNotFoundError
 from modin.data_management import factories
 
+import modin.pandas as pd
+
 
 class PandasOnTestFactory(factories.BaseFactory):
     """
@@ -63,6 +65,9 @@ def prepare(cls):
 factories.TestOnPythonFactory = TestOnPythonFactory
 factories.FooOnBarFactory = FooOnBarFactory
 
+# register them as known "no init" engines for modin.pandas
+pd._NOINIT_ENGINES |= {"Test", "Bar"}
+
 
 def test_default_engine():
     assert issubclass(EngineDispatcher.get_engine(), factories.BaseFactory)

modin/pandas/__init__.py

@@ -97,6 +97,9 @@
 
 _is_first_update = {}
 dask_client = None
+_NOINIT_ENGINES = {
+    "Python"
+}  # engines that don't require initialization, useful for unit tests
 
 
 def _update_engine(publisher: Publisher):
@@ -157,7 +160,7 @@ def init_remote_ray():
 
         num_cpus = remote_ray.cluster_resources()["CPU"]
 
-    elif publisher.get() != "Python":
+    elif publisher.get() not in _NOINIT_ENGINES:
         raise ImportError("Unrecognized execution engine: {}.".format(publisher.get()))
 
     _is_first_update[publisher.get()] = False