优化单测代码2，有针对性地缩小单测范围。

Author: AuferGachet

fastdeploy/entrypoints/openai/serving_completion.py

@@ -236,7 +236,7 @@ async def completion_full_generator(
 
     async def _echo_back_prompt(self, request, res, idx):
         # 如果是第一个响应片段，拼接prompt到text前
-        if res["outputs"].get("send_idx", -1) == 0 and request.prompt is not None and request.echo:
+        if res["outputs"].get("send_idx", -1) == 0 and request.echo:
             if isinstance(request.prompt, list):
                 prompt_text = request.prompt[idx]
             else:

test/entrypoints/openai/test_completion_echo.py

@@ -72,6 +72,7 @@ def mock_echo_side_effect(req, res, idx):
 
             # 验证结果
             self.assertEqual(mock_response["outputs"]["text"], "test prompttest output")
+            self.assertEqual(request.prompt, "test prompt")
 
     def test_multi_prompt_non_streaming(self):
         """测试多prompt非流式响应"""
@@ -142,8 +143,8 @@ def mock_echo_side_effect(req, res, idx):
             # 验证结果
             self.assertEqual(mock_responses[0]["outputs"]["text"], "prompt1 response1")
             self.assertEqual(mock_responses[1]["outputs"]["text"], "prompt2 response2")
+            self.assertEqual(request.prompt, ["prompt1", "prompt2"])
 
 
 if __name__ == "__main__":
     unittest.main()
-    #     self.assertEqual(results[4], "data: [DONE]\n\n")