[Bugfix] deepseek_r1_reasoning_parser put reason content in wrong field when no end think tag in output

Signed-off-by: Mo Xu <moxu@amazon.com>

Author: moxu-amzn

tests/entrypoints/openai/reasoning_parsers/test_deepseekr1_reasoning_parser.py

@@ -24,10 +24,10 @@
     "reasoning_content": "This is a reasoning section",
     "content": None,
 }
-NO_REASONING = {
+NO_CONTENT = {
     "output": "This is content",
-    "reasoning_content": None,
-    "content": "This is content",
+    "reasoning_content": "This is content",
+    "content": None,
 }
 NO_REASONING_STREAMING = {
     "output": "This is a reasoning section",
@@ -98,8 +98,8 @@
     ),
     pytest.param(
         False,
-        NO_REASONING,
-        id="no_reasoning_token",
+        NO_CONTENT,
+        id="no_content_token",
     ),
     pytest.param(
         True,

vllm/entrypoints/openai/reasoning_parsers/deepseek_r1_reasoning_parser.py

@@ -128,7 +128,7 @@ def extract_reasoning_content(
         # Thus we assume the reasoning content is always at the start.
         # Ref https://huggingface.co/deepseek-ai/DeepSeek-R1/commit/8a58a132790c9935686eb97f042afa8013451c9f
         if self.think_end_token not in model_output:
-            return None, model_output
+            return model_output, None
         else:
             # Add a start token if it's missing to keep compatibility.
             if self.think_start_token not in model_output: