test: add SingleCallOrchestrator tests with fake backend

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_single_call_orchestrator.py

@@ -0,0 +1,78 @@
+"""Tests for SingleCallOrchestrator using a fake LLM backend."""
+
+import json
+from agents.orchestrator import SingleCallOrchestrator
+from tests.conftest import FakeLLMBackend
+
+
+class TestSingleCallOrchestrator:
+    def _make_orchestrator(self, response_json: str, tmp_output_dir):
+        backend = FakeLLMBackend(response_json)
+        return SingleCallOrchestrator(backend=backend, output_dir=tmp_output_dir), backend
+
+    def test_response_shape(self, tmp_output_dir):
+        resp = json.dumps({"agents": [
+            {"id": "design", "message": "An L-bracket would work."},
+        ]})
+        orch, _ = self._make_orchestrator(resp, tmp_output_dir)
+        result = orch.chat_turn("I need a bracket", history=[])
+        assert "responses" in result
+        assert "preview" in result
+        assert "design_state" in result
+
+    def test_passes_message_to_backend(self, tmp_output_dir):
+        resp = json.dumps({"agents": [{"id": "design", "message": "OK"}]})
+        orch, backend = self._make_orchestrator(resp, tmp_output_dir)
+        orch.chat_turn("Test message", history=[])
+        assert len(backend.calls) == 1
+        last_user_msg = backend.calls[0][-1]["content"]
+        assert "Test message" in last_user_msg
+
+    def test_mentions_restrict_agents(self, tmp_output_dir):
+        resp = json.dumps({"agents": [{"id": "cnc", "message": "3-axis OK"}]})
+        orch, _ = self._make_orchestrator(resp, tmp_output_dir)
+        result = orch.chat_turn("check this", history=[], mentions=["cnc"])
+        agent_ids = [r["agent_id"] for r in result["responses"]]
+        assert "cnc" in agent_ids
+
+    def test_invalid_json_fallback(self, tmp_output_dir):
+        orch, _ = self._make_orchestrator("not json at all", tmp_output_dir)
+        result = orch.chat_turn("help", history=[])
+        assert len(result["responses"]) > 0
+        assert result["responses"][0]["agent_id"] == "design"
+
+    def test_llm_exception_fallback(self, tmp_output_dir):
+        class RaisingBackend:
+            def generate(self, messages):
+                raise RuntimeError("API error")
+
+        orch = SingleCallOrchestrator(backend=RaisingBackend(), output_dir=tmp_output_dir)
+        result = orch.chat_turn("Design a part", history=[])
+        assert len(result["responses"]) > 0
+
+    def test_unknown_agent_id_filtered(self, tmp_output_dir):
+        resp = json.dumps({"agents": [
+            {"id": "nonexistent", "message": "I don't exist"},
+            {"id": "design", "message": "Real agent"},
+        ]})
+        orch, _ = self._make_orchestrator(resp, tmp_output_dir)
+        result = orch.chat_turn("test", history=[])
+        agent_ids = [r["agent_id"] for r in result["responses"]]
+        assert "nonexistent" not in agent_ids
+        assert "design" in agent_ids
+
+    def test_history_forwarded_to_backend(self, tmp_output_dir, sample_history):
+        resp = json.dumps({"agents": [{"id": "design", "message": "OK"}]})
+        orch, backend = self._make_orchestrator(resp, tmp_output_dir)
+        orch.chat_turn("continue", history=sample_history)
+        user_content = backend.calls[0][-1]["content"]
+        assert "servo bracket" in user_content.lower() or "MG996R" in user_content
+
+    def test_design_state_returned(self, tmp_output_dir):
+        resp = json.dumps({"agents": [
+            {"id": "engineering", "message": "Use aluminum 6061 with 3mm walls."},
+        ]})
+        orch, _ = self._make_orchestrator(resp, tmp_output_dir)
+        result = orch.chat_turn("material?", history=[])
+        assert "design_state" in result
+        assert isinstance(result["design_state"], dict)