Forward unknown tool calls instead of dropping (#12226)

test/srt/function_call/test_unknown_tool_name.py

@@ -0,0 +1,69 @@
+import json
+import logging
+
+from sglang.srt.entrypoints.openai.protocol import Function, Tool
+from sglang.srt.environ import envs
+from sglang.srt.function_call.base_format_detector import BaseFormatDetector
+from sglang.srt.function_call.core_types import StreamingParseResult
+
+
+class DummyDetector(BaseFormatDetector):
+    def has_tool_call(self, text: str) -> bool:
+        return True
+
+    def detect_and_parse(self, text: str, tools):
+        action = json.loads(text)
+        return StreamingParseResult(
+            normal_text="", calls=self.parse_base_json(action, tools)
+        )
+
+
+def test_unknown_tool_name_dropped_default(caplog):
+    """Test that unknown tools are dropped by default (legacy behavior)."""
+    with envs.SGLANG_FORWARD_UNKNOWN_TOOLS.override(False):
+        tools = [
+            Tool(
+                function=Function(
+                    name="get_weather", parameters={"type": "object", "properties": {}}
+                )
+            )
+        ]
+        detector = DummyDetector()
+        with caplog.at_level(
+            logging.WARNING, logger="sglang.srt.function_call.base_format_detector"
+        ):
+            result = detector.detect_and_parse(
+                '{"name":"unknown_tool","parameters":{"city":"Paris"}}', tools
+            )
+        assert any(
+            "Model attempted to call undefined function: unknown_tool" in m
+            for m in caplog.messages
+        )
+        assert len(result.calls) == 0  # dropped in default mode
+
+
+def test_unknown_tool_name_forwarded(caplog):
+    """Test that unknown tools are forwarded when env var is True."""
+    with envs.SGLANG_FORWARD_UNKNOWN_TOOLS.override(True):
+        tools = [
+            Tool(
+                function=Function(
+                    name="get_weather", parameters={"type": "object", "properties": {}}
+                )
+            )
+        ]
+        detector = DummyDetector()
+        with caplog.at_level(
+            logging.WARNING, logger="sglang.srt.function_call.base_format_detector"
+        ):
+            result = detector.detect_and_parse(
+                '{"name":"unknown_tool","parameters":{"city":"Paris"}}', tools
+            )
+        assert any(
+            "Model attempted to call undefined function: unknown_tool" in m
+            for m in caplog.messages
+        )
+        assert len(result.calls) == 1
+        assert result.calls[0].name == "unknown_tool"
+        assert result.calls[0].tool_index == -1
+        assert json.loads(result.calls[0].parameters)["city"] == "Paris"