[PD] Add simple unit test for disaggregation feature (#5654)

Signed-off-by: Shangming Cai <caishangming@linux.alibaba.com>

.github/workflows/pr-test.yml

@@ -252,6 +252,24 @@ jobs:
           cd test/srt
           python3 test_moe_eval_accuracy_large.py
 
+  unit-test-backend-pd:
+    if: (github.repository == 'sgl-project/sglang' || github.event_name == 'pull_request') &&
+        github.event.pull_request.draft == false
+    runs-on: 8-gpu-runner
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install dependencies
+        run: |
+          bash scripts/ci_install_dependency_8_gpu.sh
+
+      - name: Run test
+        timeout-minutes: 10
+        run: |
+          cd test/srt
+          python3 -m unittest test_disaggregation.TestDisaggregationMooncake.test_gsm8k
+
   large-scale-test-8-gpu:
     if: (github.repository == 'sgl-project/sglang' || github.event_name == 'pull_request') &&
         github.event.pull_request.draft == false