Add a test for mixed precision (#9806)

tests/test_modeling_tf_longformer.py

@@ -340,14 +340,25 @@ class TFLongformerModelTest(TFModelTesterMixin, unittest.TestCase):
 
     @slow
     def test_saved_model_with_attentions_output(self):
-        # longformer has special attentions which are not
-        # compatible in graph mode
+        # This test don't pass because of the error:
+        # condition [13,8,4,5], then [13,8,4,5], and else [13,8,4,6] must be broadcastable
+        # This occurs line 323 in modeling_tf_led.py because the condition line 255
+        # returns a tensor of shape
+        # [batch_size, seq_len, self.num_heads, self.one_sided_attn_window_size * 2 + 2]
+        # if is_global_attn is True and a tensor of shape
+        # [batch_size, seq_len, self.num_heads, self.one_sided_attn_window_size * 2 + 1]
+        # This is due to the tf.concat call line 703 that adds one dimension
+        # Need to check with PVP how to properly fix this
         pass
 
     def test_saved_model_creation(self):
         # This test is too long (>30sec) and makes fail the CI
         pass
 
+    def test_mixed_precision(self):
+        # TODO JP: Make Longformer float16 compliant
+        pass
+
 
 @require_tf
 @require_sentencepiece