[tune] checkpoint_dir test (#8024)

python/ray/tune/tests/test_tune_save_restore.py

@@ -9,6 +9,7 @@ import ray
 from ray import tune
 from ray.rllib import _register_all
 from ray.tune import Trainable
+from ray.tune.utils import validate_save_restore
 
 
 class SerialTuneRelativeLocalDirTest(unittest.TestCase):
@@ -37,11 +38,13 @@ class SerialTuneRelativeLocalDirTest(unittest.TestCase):
             self.state.update(extra_data)
 
     def setUp(self):
+        self.absolute_local_dir = None
         ray.init(num_cpus=1, num_gpus=0, local_mode=self.local_mode)
 
     def tearDown(self):
-        shutil.rmtree(self.absolute_local_dir, ignore_errors=True)
-        self.absolute_local_dir = None
+        if self.absolute_local_dir is not None:
+            shutil.rmtree(self.absolute_local_dir, ignore_errors=True)
+            self.absolute_local_dir = None
         ray.shutdown()
         # Without this line, test_tune_server.testAddTrial would fail.
         _register_all()
@@ -147,6 +150,31 @@ class SerialTuneRelativeLocalDirTest(unittest.TestCase):
         self._train(exp_name, local_dir, local_dir)
         self._restore(exp_name, local_dir, local_dir)
 
+    def testCheckpointWithNoop(self):
+        """Tests that passing the checkpoint_dir right back works."""
+
+        class MockTrainable(Trainable):
+            def _setup(self, config):
+                pass
+
+            def _train(self):
+                return {"score": 1}
+
+            def _save(self, checkpoint_dir):
+                with open(os.path.join(checkpoint_dir, "test.txt"), "wb") as f:
+                    pickle.dump("test", f)
+                return checkpoint_dir
+
+            def _restore(self, checkpoint_dir):
+                with open(os.path.join(checkpoint_dir, "test.txt"), "rb") as f:
+                    x = pickle.load(f)
+
+                assert x == "test"
+                return checkpoint_dir
+
+        validate_save_restore(MockTrainable)
+        validate_save_restore(MockTrainable, use_object_store=True)
+
 
 if __name__ == "__main__":
     import pytest