add tests for the new sharded ddp fairscale integration (#9177)

examples/seq2seq/test_finetune_trainer.py

@@ -14,10 +14,12 @@
 
 import os
 import sys
+import unittest
 from unittest.mock import patch
 
 from transformers import BertTokenizer, EncoderDecoderModel
 from transformers.file_utils import is_datasets_available
+from transformers.integrations import is_fairscale_available
 from transformers.testing_utils import (
     TestCasePlus,
     execute_subprocess_async,
@@ -38,9 +40,20 @@ MARIAN_MODEL = "sshleifer/student_marian_en_ro_6_1"
 MBART_TINY = "sshleifer/tiny-mbart"
 
 
+# a candidate for testing_utils
+def require_fairscale(test_case):
+    """
+    Decorator marking a test that requires fairscale
+    """
+    if not is_fairscale_available():
+        return unittest.skip("test requires fairscale")(test_case)
+    else:
+        return test_case
+
+
 class TestFinetuneTrainer(TestCasePlus):
-    def finetune_trainer_quick(self, distributed=None):
-        output_dir = self.run_trainer(1, "12", MBART_TINY, 1, distributed)
+    def finetune_trainer_quick(self, distributed=None, extra_args_str=None):
+        output_dir = self.run_trainer(1, "12", MBART_TINY, 1, distributed, extra_args_str)
         logs = TrainerState.load_from_json(os.path.join(output_dir, "trainer_state.json")).log_history
         eval_metrics = [log for log in logs if "eval_loss" in log.keys()]
         first_step_stats = eval_metrics[0]
@@ -59,6 +72,16 @@ class TestFinetuneTrainer(TestCasePlus):
     def test_finetune_trainer_ddp(self):
         self.finetune_trainer_quick(distributed=True)
 
+    @require_torch_multi_gpu
+    @require_fairscale
+    def test_finetune_trainer_ddp_sharded_ddp(self):
+        self.finetune_trainer_quick(distributed=True, extra_args_str="--sharded_ddp")
+
+    @require_torch_multi_gpu
+    @require_fairscale
+    def test_finetune_trainer_ddp_sharded_ddp_fp16(self):
+        self.finetune_trainer_quick(distributed=True, extra_args_str="--sharded_ddp --fp16")
+
     @slow
     def test_finetune_trainer_slow(self):
         # There is a missing call to __init__process_group somewhere
@@ -195,7 +218,13 @@ class TestFinetuneTrainer(TestCasePlus):
         trainer.train()
 
     def run_trainer(
-        self, eval_steps: int, max_len: str, model_name: str, num_train_epochs: int, distributed: bool = False
+        self,
+        eval_steps: int,
+        max_len: str,
+        model_name: str,
+        num_train_epochs: int,
+        distributed: bool = False,
+        extra_args_str: str = None,
     ):
         data_dir = self.examples_dir / "seq2seq/test_data/wmt_en_ro"
         output_dir = self.get_auto_remove_tmp_dir()
@@ -231,6 +260,9 @@ class TestFinetuneTrainer(TestCasePlus):
         """.split()
         # --eval_beams  2
 
+        if extra_args_str is not None:
+            args.extend(extra_args_str.split())
+
         if distributed:
             n_gpu = get_gpu_count()
             distributed_args = f"""