Add test for mixture of experts

Summary: Pull Request resolved: https://github.com/pytorch/fairseq/pull/543

Differential Revision: D14259481

Pulled By: myleott

fbshipit-source-id: fcb0a150b8e851cf86ea5ed1f083f56e1600588e

examples/translation_moe/README.md

@@ -43,7 +43,7 @@ $ fairseq-generate data-bin/wmt17_en_de \
     --task translation_moe \
     --method hMoElp --mean-pool-gating-network \
     --num-experts 3 \
-    --gen-expert 0 \
+    --gen-expert 0
 ```
 
 ## Evaluate

tests/test_binaries.py

@@ -160,6 +160,25 @@ class TestTranslation(unittest.TestCase):
                 ])
                 generate_main(data_dir)
 
+    def test_mixture_of_experts(self):
+        with contextlib.redirect_stdout(StringIO()):
+            with tempfile.TemporaryDirectory('test_moe') as data_dir:
+                create_dummy_data(data_dir)
+                preprocess_translation_data(data_dir)
+                train_translation_model(data_dir, 'transformer_iwslt_de_en', [
+                    '--task', 'translation_moe',
+                    '--method', 'hMoElp',
+                    '--mean-pool-gating-network',
+                    '--num-experts', '3',
+                ])
+                generate_main(data_dir, [
+                    '--task', 'translation_moe',
+                    '--method', 'hMoElp',
+                    '--mean-pool-gating-network',
+                    '--num-experts', '3',
+                    '--gen-expert', '0'
+                ])
+
 
 class TestStories(unittest.TestCase):