[Bugfix] Make spec. decode respect per-request seed. (#6034)

Signed-off-by: Thomas Parnell <tpa@zurich.ibm.com>
Co-authored-by: Nick Hill <nickhill@us.ibm.com>

tests/spec_decode/e2e/test_seed.py

@@ -0,0 +1,44 @@
+import pytest
+
+from .conftest import run_equality_correctness_test
+
+
+@pytest.mark.parametrize(
+    "common_llm_kwargs",
+    [{
+        "model": "JackFram/llama-68m",
+
+        # Skip cuda graph recording for fast test.
+        "enforce_eager": True,
+
+        # Required for spec decode.
+        "use_v2_block_manager": True,
+
+        # speculative model
+        "speculative_model": "JackFram/llama-160m",
+
+        # num speculative tokens
+        "num_speculative_tokens": 3,
+    }])
+@pytest.mark.parametrize("per_test_common_llm_kwargs", [{}])
+@pytest.mark.parametrize("baseline_llm_kwargs", [{}])
+@pytest.mark.parametrize("batch_size", [1, 8, 32])
+@pytest.mark.parametrize("temperature", [0.1, 1.0])
+@pytest.mark.parametrize(
+    "output_len",
+    [
+        # Use smaller output len for fast test.
+        10,
+    ])
+@pytest.mark.parametrize("seed", [1])
+def test_seeded_consistency(baseline_llm_generator, batch_size: int,
+                            temperature: float, output_len: int):
+    """Verify outputs are consistent across multiple runs with same seed
+    """
+    run_equality_correctness_test(baseline_llm_generator,
+                                  baseline_llm_generator,
+                                  batch_size,
+                                  max_output_len=output_len,
+                                  temperature=temperature,
+                                  seeded=True,
+                                  force_output_len=True)