🧪 add long context test (#330)

# Description

This adds a failing test case for handling batch size 4 at 4k context
length with continuous batching.

This tests the `eager` backend against the `sendnn` backend, which is
currently failing on `quay.io/ibm-aiu/spyre-base:2025_07_18-amd64`

Signed-off-by: Joe Runde <[email protected]>

Author: joerunde

tests/e2e/test_spyre_cb.py

@@ -4,7 +4,8 @@
 """
 
 import pytest
-from spyre_util import generate_spyre_vllm_output, get_spyre_model_list
+from spyre_util import (generate_spyre_vllm_output, get_chicken_soup_prompts,
+                        get_spyre_model_list)
 from vllm import SamplingParams
 
 
@@ -41,3 +42,57 @@ def test_cb_max_tokens(
                                    max_num_seqs=2,
                                    use_cb=True,
                                    monkeypatch=monkeypatch)
+
+
+@pytest.mark.cb
+@pytest.mark.spyre
+@pytest.mark.xfail  # TODO: remove once a spyre-base image supports this
+@pytest.mark.parametrize("model", get_spyre_model_list())
+def test_continuous_batching_with_long_contexts(model, monkeypatch):
+    """Tests that continuous batching generates the same outputs on the spyre
+    cards as it does on cpu, when the max context length is set to 4k.
+    This ensures that the compiler is generating the correct programs for long
+    context cases, but we test here with small prompts for speed.
+
+    Importantly, we're generating the cpu results to compare against using vllm
+    as well, instead of using transformers directly. This ensures that the model
+    code is all the same, and the only difference is the torch compilation
+    backend.
+    """
+    max_model_len = 4096
+    max_num_seqs = 4
+    prompts = get_chicken_soup_prompts(4)
+
+    sampling_params = SamplingParams(max_tokens=20,
+                                     temperature=0,
+                                     ignore_eos=True,
+                                     logprobs=0)
+
+    vllm_cpu_results = generate_spyre_vllm_output(
+        model=model,
+        prompts=prompts,
+        max_model_len=max_model_len,
+        block_size=max_model_len,
+        sampling_params=sampling_params,
+        tensor_parallel_size=1,
+        backend="eager",
+        max_num_seqs=max_num_seqs,
+        use_cb=True,
+        monkeypatch=monkeypatch)
+
+    vllm_spyre_results = generate_spyre_vllm_output(
+        model=model,
+        prompts=prompts,
+        max_model_len=max_model_len,
+        block_size=max_model_len,
+        sampling_params=sampling_params,
+        tensor_parallel_size=1,
+        backend="sendnn",
+        max_num_seqs=max_num_seqs,
+        use_cb=True,
+        monkeypatch=monkeypatch)
+
+    for i in range(len(vllm_cpu_results)):
+        # As long as no sequences have top candidate tokens with very close
+        # logprobs, the generated text should be identical.
+        assert vllm_cpu_results[i]["text"] == vllm_spyre_results[i]["text"]