test: add pytest config and shared test fixtures

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

pyproject.toml

@@ -20,3 +20,10 @@ dependencies = [
 
 [dependency-groups]
 dev = ["ruff", "pytest"]
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+pythonpath = ["."]
+markers = [
+    "requires_cadquery: marks tests that need CadQuery installed",
+]

tests/conftest.py

@@ -0,0 +1,61 @@
+"""Shared fixtures for NeuralCAD tests."""
+
+import pytest
+from pathlib import Path
+
+
+@pytest.fixture
+def tmp_output_dir(tmp_path):
+    """Temporary output directory for model files."""
+    out = tmp_path / "output"
+    out.mkdir()
+    return out
+
+
+@pytest.fixture
+def sample_history():
+    """A typical multi-turn conversation history."""
+    return [
+        {"role": "user", "content": "I need a servo bracket for an MG996R"},
+        {"role": "agent", "agent_id": "design", "content": "I'd suggest an L-bracket with a servo pocket on the vertical face."},
+        {"role": "agent", "agent_id": "engineering", "content": "3mm wall thickness in aluminum 6061-T6 should handle the load."},
+        {"role": "user", "content": "Make it 60mm wide with M4 base mounting holes"},
+    ]
+
+
+@pytest.fixture
+def empty_design_state():
+    """Empty design state dict."""
+    return {}
+
+
+@pytest.fixture
+def populated_design_state():
+    """Design state with some decisions already made."""
+    return {
+        "part_name": "servo_bracket",
+        "material": "aluminum 6061",
+        "dimensions": {"width": 60.0},
+        "features": ["4x M4 holes"],
+        "decisions": ["L-bracket form factor"],
+    }
+
+
+class FakeLLMBackend:
+    """A controllable fake LLM backend for testing orchestrators."""
+
+    def __init__(self, response: str = '{"agents": []}'):
+        self.response = response
+        self.calls: list[list[dict]] = []
+
+    def generate(self, messages: list[dict]) -> str:
+        self.calls.append(messages)
+        return self.response
+
+
+@pytest.fixture
+def fake_backend():
+    """FakeLLMBackend factory — call with desired JSON response."""
+    def _make(response: str = '{"agents": []}'):
+        return FakeLLMBackend(response)
+    return _make