feat: Add streaming test for <think> tags in reasoning process

tests/basic/test_reasoning.py

@@ -225,6 +225,98 @@ class TestReasoning(unittest.TestCase):
             self.assertLess(
                 reasoning_pos, main_pos, "Reasoning content should appear before main content"
             )
+    
+    def test_send_with_think_tags_stream(self):
+        """Test that streaming with <think> tags is properly processed and formatted."""
+        # Setup IO with pretty output for streaming
+        io = InputOutput(pretty=True)
+        mock_mdstream = MagicMock()
+        io.get_assistant_mdstream = MagicMock(return_value=mock_mdstream)
+
+        # Setup model and coder
+        model = Model("gpt-3.5-turbo")
+        model.remove_reasoning = "think"  # Set to remove <think> tags
+        coder = Coder.create(model, None, io=io, stream=True)
+
+        # Ensure the coder shows pretty output
+        coder.show_pretty = MagicMock(return_value=True)
+
+        # Mock streaming response chunks
+        class MockStreamingChunk:
+            def __init__(self, content=None, finish_reason=None):
+                self.choices = [MagicMock()]
+                self.choices[0].delta = MagicMock()
+                self.choices[0].finish_reason = finish_reason
+
+                # Set content if provided
+                if content is not None:
+                    self.choices[0].delta.content = content
+                else:
+                    # Need to handle attribute access that would raise AttributeError
+                    delattr(self.choices[0].delta, "content")
+
+        # Create chunks to simulate streaming with think tags
+        chunks = [
+            # Start with open think tag
+            MockStreamingChunk(content="<think>\n"),
+            # Reasoning content inside think tags
+            MockStreamingChunk(content="My step-by-step "),
+            MockStreamingChunk(content="reasoning process\n"),
+            # Close think tag
+            MockStreamingChunk(content="</think>\n\n"),
+            # Main content
+            MockStreamingChunk(content="Final "),
+            MockStreamingChunk(content="answer "),
+            MockStreamingChunk(content="after reasoning"),
+            # End the response
+            MockStreamingChunk(finish_reason="stop"),
+        ]
+
+        # Create a mock hash object
+        mock_hash = MagicMock()
+        mock_hash.hexdigest.return_value = "mock_hash_digest"
+
+        # Mock the model's send_completion to return the hash and completion
+        with patch.object(model, "send_completion", return_value=(mock_hash, chunks)):
+            # Set mdstream directly on the coder object
+            coder.mdstream = mock_mdstream
+
+            # Call send with a simple message
+            messages = [{"role": "user", "content": "test prompt"}]
+            list(coder.send(messages))
+
+            # Verify mdstream.update was called multiple times
+            mock_mdstream.update.assert_called()
+
+            coder.live_incremental_response(True)
+
+            # Explicitly get all calls to update
+            update_calls = mock_mdstream.update.call_args_list
+
+            # There should be at least two calls - one for streaming and one final
+            self.assertGreaterEqual(
+                len(update_calls), 2, "Should have at least two calls to update (streaming + final)"
+            )
+
+            # Check that at least one call has final=True (should be the last one)
+            has_final_true = any(call[1].get("final", False) for call in update_calls)
+            self.assertTrue(has_final_true, "At least one update call should have final=True")
+
+            # Get the text from the last update call
+            final_text = update_calls[-1][0][0]
+
+            # The final text should include both reasoning and main content with proper formatting
+            self.assertIn("> Thinking ...", final_text)
+            self.assertIn("My step-by-step reasoning process", final_text)
+            self.assertIn("> ... done thinking", final_text)
+            self.assertIn("Final answer after reasoning", final_text)
+
+            # Ensure proper order: reasoning first, then main content
+            reasoning_pos = final_text.find("My step-by-step reasoning process")
+            main_pos = final_text.find("Final answer after reasoning")
+            self.assertLess(
+                reasoning_pos, main_pos, "Reasoning content should appear before main content"
+            )
 
 
 if __name__ == "__main__":