server: respect the ignore eos flag (#21203)

tools/server/tests/unit/test_ignore_eos.py

@@ -0,0 +1,43 @@
+import pytest
+from utils import *
+
+server = ServerPreset.tinyllama2()
+
+
+@pytest.fixture(autouse=True)
+def create_server():
+    global server
+    server = ServerPreset.tinyllama2()
+
+
+def test_ignore_eos_populates_logit_bias():
+    """ignore_eos=true must add EOG logit biases to generation_settings."""
+    global server
+    server.start()
+    res = server.make_request("POST", "/completion", data={
+        "n_predict": 8,
+        "prompt": "Once upon a time",
+        "ignore_eos": True,
+        "temperature": 0.0,
+    })
+    assert res.status_code == 200
+    # EOG token biases must be present with -inf bias
+    logit_bias = res.body["generation_settings"]["logit_bias"]
+    assert len(logit_bias) > 0
+    for entry in logit_bias:
+        assert entry["bias"] is None  # null in JSON represents -inf
+
+
+def test_ignore_eos_false_no_logit_bias():
+    """ignore_eos=false (default) must NOT add EOG logit biases."""
+    global server
+    server.start()
+    res = server.make_request("POST", "/completion", data={
+        "n_predict": 8,
+        "prompt": "Once upon a time",
+        "ignore_eos": False,
+        "temperature": 0.0,
+    })
+    assert res.status_code == 200
+    logit_bias = res.body["generation_settings"]["logit_bias"]
+    assert len(logit_bias) == 0