Add unittests for Universal Assisted generation

tests/test_universal_assisted_generation.py

@@ -0,0 +1,96 @@
+import unittest
+
+import torch
+from transformers import AutoTokenizer, AutoModelForCausalLM, GenerationConfig
+from transformers.generation.candidate_generator import UniversalSpeculativeDecodingGenerator
+
+
+device = "cuda" if torch.cuda.is_available() else "cpu"
+
+class TestUniversalSpeculativeDecoding(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        # Setup main and assistant models
+        cls.main_model = AutoModelForCausalLM.from_pretrained(
+            "meta-llama/Llama-3.2-1B-Instruct").to(device)
+        cls.assistant_model = AutoModelForCausalLM.from_pretrained(
+            "hf-internal-testing/tiny-random-gpt2").to(device)
+        cls.main_tokenizer = AutoTokenizer.from_pretrained(
+            "meta-llama/Llama-3.2-1B-Instruct")
+        cls.assistant_tokenizer = AutoTokenizer.from_pretrained(
+            "hf-internal-testing/tiny-random-gpt2")
+        cls.generation_config = GenerationConfig()
+
+        # Ensure required tokens exist
+        if cls.main_tokenizer.pad_token_id is None:
+            cls.main_tokenizer.pad_token_id = cls.main_tokenizer.eos_token_id
+        if cls.main_tokenizer.bos_token_id is None:
+            cls.main_tokenizer.bos_token_id = cls.main_tokenizer.eos_token_id
+
+    def setUp(self):
+        self.input_ids = torch.tensor([[1, 2, 3]]).to(device)
+        self.model_kwargs = {
+            "attention_mask": torch.ones_like(self.input_ids).to(device),
+        }
+        self.generator = UniversalSpeculativeDecodingGenerator(
+            input_ids=self.input_ids,
+            assistant_model=self.assistant_model,
+            target_tokenizer=self.main_tokenizer,
+            assistant_tokenizer=self.assistant_tokenizer,
+            generation_config=self.generation_config,
+            model_kwargs=self.model_kwargs,
+            target_vocab_size=self.main_tokenizer.vocab_size,
+        )
+
+    def test_basic_generation(self):
+        """Test basic speculative decoding works"""
+        input_text = "The quick brown fox"
+        input_ids = self.main_tokenizer.encode(input_text, return_tensors="pt")
+        self.generator.input_ids = input_ids
+        candidates, scores = self.generator.get_candidates(input_ids)
+
+        self.assertIsNotNone(candidates)
+        self.assertIsNotNone(scores)
+        self.assertTrue(torch.is_tensor(candidates))
+        self.assertTrue(torch.is_tensor(scores))
+
+    def test_mismatched_vocabularies(self):
+        """Test handling of mismatched vocabularies between models"""
+        # Create input with tokens present in main but not assistant vocab
+        # Find a token that is not in the assistant tokenizer but in 
+        # the main tokenizer.
+        missing_token = next(
+            token for token in self.main_tokenizer.get_vocab()
+            if token not in self.assistant_tokenizer.get_vocab() and
+               token not in self.main_tokenizer.all_special_tokens and
+               "reserved_" not in token
+        )
+        input_ids = torch.tensor([[self.main_tokenizer.convert_tokens_to_ids(missing_token)]]) 
+        self.generator.input_ids = input_ids
+        candidates, scores = self.generator.get_candidates(input_ids)
+        self.assertIsNotNone(candidates)
+
+    def test_speculation_depth(self):
+        """Test different speculation depths"""
+        input_ids = self.main_tokenizer.encode("Test text", return_tensors="pt")
+        self.generator.input_ids = input_ids
+
+        for depth in [1, 8, 17]:
+            self.generator.num_assistant_tokens = depth
+            candidates, scores = self.generator.get_candidates(input_ids)
+            self.assertLessEqual(
+                candidates.shape[1] - input_ids.shape[1], depth
+            )
+
+    def test_device_consistency(self):
+        """Test handling of inputs on different devices"""
+        if torch.cuda.is_available():
+            input_ids = torch.tensor([[1, 2, 3]]).to(
+                self.generator.assistant_model.device)
+            self.generator.input_ids = input_ids
+            candidates, scores = self.generator.get_candidates(input_ids)
+            self.assertEqual(candidates.device, input_ids.device)
+
+
+if __name__ == '__main__':
+    unittest.main()