Add kl test for swa radix cache (#17281)

test/registered/radix_cache/test_swa_radix_cache_kl.py

@@ -0,0 +1,66 @@
+import unittest
+
+from sglang.srt.utils import kill_process_tree
+from sglang.test.ci.ci_register import register_cuda_ci
+from sglang.test.kl_test_utils import (
+    test_input_output_logprobs_match_decode_cache_hit_helper,
+    test_input_output_logprobs_match_prefill_cache_hit_helper,
+)
+from sglang.test.test_utils import (
+    DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH,
+    DEFAULT_URL_FOR_TEST,
+    CustomTestCase,
+    popen_launch_server,
+)
+
+MODEL = "openai/gpt-oss-20b"
+
+ACC_THRESHOLDS = {
+    MODEL: {"kl_div": 0.002},
+}
+
+register_cuda_ci(est_time=100, suite="stage-b-test-large-1-gpu")
+
+
+class TestSWARadixCacheKL(CustomTestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.model = MODEL
+        cls.base_url = DEFAULT_URL_FOR_TEST
+        cls.process = popen_launch_server(
+            cls.model,
+            cls.base_url,
+            timeout=DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH,
+            other_args=[
+                "--tp-size",
+                "1",
+                "--mem-fraction-static",
+                "0.75",
+            ],
+        )
+
+    @classmethod
+    def tearDownClass(cls):
+        kill_process_tree(cls.process.pid)
+
+    def test_input_output_logprobs_match_prefill_cache_hit(self):
+        test_input_output_logprobs_match_prefill_cache_hit_helper(
+            self.base_url,
+            ACC_THRESHOLDS,
+            self.model,
+            max_samples=32,
+            max_new_tokens=512,
+        )
+
+    def test_input_output_logprobs_match_decode_cache_hit(self):
+        test_input_output_logprobs_match_decode_cache_hit_helper(
+            self.base_url,
+            ACC_THRESHOLDS,
+            self.model,
+            max_samples=32,
+            max_new_tokens=2048,
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()