chore: import upstream snapshot with attribution

python/ray/train/tests/test_minimal.py

@@ -0,0 +1,90 @@
+import pytest
+
+import ray
+from ray import train
+from ray.train import ScalingConfig
+from ray.train._internal.worker_group import WorkerGroup
+from ray.train.backend import Backend, BackendConfig
+from ray.train.data_parallel_trainer import DataParallelTrainer
+from ray.train.tests.util import create_dict_checkpoint, load_dict_checkpoint
+
+
+@pytest.fixture
+def ray_start_4_cpus():
+    address_info = ray.init(num_cpus=4)
+    yield address_info
+    # The code after the yield will run as teardown code.
+    ray.shutdown()
+
+
+class TestConfig(BackendConfig):
+    @property
+    def backend_cls(self):
+        return TestBackend
+
+
+class TestBackend(Backend):
+    def on_start(self, worker_group: WorkerGroup, backend_config: TestConfig):
+        pass
+
+    def on_shutdown(self, worker_group: WorkerGroup, backend_config: TestConfig):
+        pass
+
+
+def test_run(ray_start_4_cpus):
+    """Tests that Train can be run without any specific backends."""
+    num_workers = 2
+    key = "value"
+    value = 1
+    config = TestConfig()
+
+    def train_func():
+        checkpoint = train.get_checkpoint()
+        checkpoint_dict = load_dict_checkpoint(checkpoint)
+        if train.get_context().get_world_rank() == 0:
+            train.report(metrics=checkpoint_dict, checkpoint=checkpoint)
+        else:
+            train.report(metrics=checkpoint_dict)
+        return checkpoint_dict[key]
+
+    with create_dict_checkpoint({key: value}) as checkpoint:
+        trainer = DataParallelTrainer(
+            train_func,
+            backend_config=config,
+            resume_from_checkpoint=checkpoint,
+            scaling_config=ScalingConfig(num_workers=num_workers),
+        )
+        results = trainer.fit()
+
+        assert load_dict_checkpoint(results.checkpoint) == load_dict_checkpoint(
+            checkpoint
+        )
+
+
+def test_failure():
+    """Tests that backend frameworks and non-critical libraries are not imported."""
+    with pytest.raises(ModuleNotFoundError):
+        import torch  # noqa: F401
+
+    with pytest.raises(ModuleNotFoundError):
+        import tensorflow  # noqa: F401
+
+    with pytest.raises(ModuleNotFoundError):
+        import horovod  # noqa: F401
+
+    with pytest.raises(ModuleNotFoundError):
+        import accelerate  # noqa: F401
+
+    with pytest.raises(ModuleNotFoundError):
+        import transformers  # noqa: F401
+
+    with pytest.raises(ModuleNotFoundError):
+        import xgboost  # noqa: F401
+
+
+if __name__ == "__main__":
+    import sys
+
+    import pytest
+
+    sys.exit(pytest.main(["-v", "-x", __file__]))