[Test OPT] Add batch generation test opt

tests/models/opt/test_modeling_opt.py

@@ -366,6 +366,47 @@ def test_generation_pre_attn_layer_norm(self):
 
         self.assertListEqual(predicted_outputs, EXPECTED_OUTPUTS)
 
+    def test_batch_generation(self):
+        model_id = "facebook/opt-350m"
+
+        tokenizer = GPT2Tokenizer.from_pretrained(model_id)
+        model = OPTForCausalLM.from_pretrained(model_id)
+        model.to(torch_device)
+
+        tokenizer.padding_side = "left"
+
+        # use different length sentences to test batching
+        sentences = [
+            "Hello, my dog is a little",
+            "Today, I",
+        ]
+
+        inputs = tokenizer(sentences, return_tensors="pt", padding=True)
+        input_ids = inputs["input_ids"].to(torch_device)
+
+        outputs = model.generate(
+            input_ids=input_ids,
+            attention_mask=inputs["attention_mask"].to(torch_device),
+        )
+
+        inputs_non_padded = tokenizer(sentences[0], return_tensors="pt").input_ids.to(torch_device)
+        output_non_padded = model.generate(input_ids=inputs_non_padded)
+
+        num_paddings = inputs_non_padded.shape[-1] - inputs["attention_mask"][-1].long().sum().cpu().item()
+        inputs_padded = tokenizer(sentences[1], return_tensors="pt").input_ids.to(torch_device)
+        output_padded = model.generate(input_ids=inputs_padded, max_length=model.config.max_length - num_paddings)
+
+        batch_out_sentence = tokenizer.batch_decode(outputs, skip_special_tokens=True)
+        non_padded_sentence = tokenizer.decode(output_non_padded[0], skip_special_tokens=True)
+        padded_sentence = tokenizer.decode(output_padded[0], skip_special_tokens=True)
+
+        expected_output_sentence = [
+            "Hello, my dog is a little bit of a dork.\nI'm a little bit",
+            "Today, I was in the middle of a conversation with a friend about the",
+        ]
+        self.assertListEqual(expected_output_sentence, batch_out_sentence)
+        self.assertListEqual(batch_out_sentence, [non_padded_sentence, padded_sentence])
+
     def test_generation_post_attn_layer_norm(self):
         model_id = "facebook/opt-350m"