[TEST]Add mooncake common method for tests (#6194)

### What this PR does / why we need it?
This PR adds mooncake common method to conftest, we need it to add more
test cases later
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
by running a test
- vLLM version: v0.14.0
- vLLM main:
d68209402d

Signed-off-by: jiangyunfan1 <jiangyunfan1@h-partners.com>

tests/e2e/conftest.py

@@ -169,6 +169,52 @@ def cleanup_dist_env_and_memory(shutdown_ray: bool = False):
         torch.npu.reset_peak_memory_stats()
 
 
+class MooncakeLauncher:
+
+    def __init__(
+        self,
+        mooncake_port,
+        mooncake_metrics_port,
+        eviction_high_watermark_ratio=0.8,
+        eviction_ratio=0.05,
+    ):
+        self.mooncake_port = mooncake_port
+        self.mooncake_metrics_port = mooncake_metrics_port
+        self.eviction_high_watermark_ratio = eviction_high_watermark_ratio
+        self.eviction_ratio = eviction_ratio
+
+    def __enter__(self):
+        cmd = [
+            "mooncake_master",
+            "--eviction_high_watermark_ratio",
+            str(self.eviction_high_watermark_ratio),
+            "--eviction_ratio",
+            str(self.eviction_ratio),
+            "--port",
+            str(self.mooncake_port),
+            "--metrics_port",
+            str(self.mooncake_metrics_port),
+        ]
+
+        logger.info("Launching mooncake: %s", " ".join(cmd))
+        curr_ld_path = os.environ.get("LD_LIBRARY_PATH", "")
+        mooncake_ld_path = "/usr/local/Ascend/ascend-toolkit/latest/python/site-packages/mooncake:"
+        os.environ["LD_LIBRARY_PATH"] = mooncake_ld_path + curr_ld_path
+        env = os.environ.copy()
+        self.process = subprocess.Popen(cmd, env=env)
+        return self
+
+    def __exit__(self, exc_type, exc, tb):
+        if not self.process:
+            return
+        logger.info("Stopping mooncake server...")
+        self.process.terminate()
+        try:
+            self.process.wait(timeout=5)
+        except subprocess.TimeoutExpired:
+            self.process.kill()
+
+
 class RemoteOpenAIServer:
     DUMMY_API_KEY = "token-abc123"  # vLLM's OpenAI server does not need API key