Fix windows tests

.github/workflows/python.yml

@@ -15,6 +15,7 @@ on:
 
 jobs:
   build:
+    timeout-minutes: 20
     runs-on: ${{ format('{0}-latest', matrix.os) }}
     strategy:
       fail-fast: false
@@ -26,16 +27,17 @@ jobs:
       python-version: ${{ format('{0}.{1}', matrix.python-major-version, matrix.python-minor-version) }}
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Set up Python ${{ env.python-version }}
-      uses: actions/setup-python@v2
+      uses: actions/setup-python@v5
       with:
         python-version: ${{ env.python-version }}
     - name: Install uv and Nox
       run: |
         python -m pip install --upgrade pip
         python -m pip install uv nox
     - name: Run tests using Nox
+      timeout-minutes: 15
       # Nox creates the per-version venv and uses `uv sync --frozen` (single
       # uv.lock) to install the project and dependencies into it.
       run: |

noxfile.py

@@ -1,33 +1,26 @@
 import os
-import sys
 import nox
 
 # Select the Python versions to test against (these must be installed on the system)
 python_versions = ['3.10', '3.11', '3.12']
 
-# Configure radCAD for tests
-if sys.platform.startswith('win'):
-    # Use the multiprocessing backend on Windows to avoid recursion depth errors
-    # TODO Remove this once the recursion depth issue is resolved
-    # (literal name of Backend.MULTIPROCESSING; avoids importing radcad here)
-    os.environ['RADCAD_BACKEND'] = 'MULTIPROCESSING'
-
-
 def install_dependencies(session):
     '''Install the project and its dependencies into the session venv with uv'''
+    venv = os.path.abspath(session.virtualenv.location)
     session.run(
         'uv', 'sync', '--frozen',
+        '--python', session.python,
         '--extra', 'compat',
         '--extra', 'extension-backend-ray',
-        env={'UV_PROJECT_ENVIRONMENT': session.virtualenv.location},
+        env={'UV_PROJECT_ENVIRONMENT': venv, 'VIRTUAL_ENV': venv},
         external=True,
     )
 
 @nox.session(python=python_versions)
 def tests(session):
     install_dependencies(session)
     session.run(
-        'pytest',
+        'python', '-m', 'pytest',
         # Currently failing on Windows due to recursion depth limit
         # '-n', 'auto',  # Run tests in parallel using pytest-xdist
         'tests',
@@ -37,7 +30,7 @@ def tests(session):
 def benchmarks(session):
     install_dependencies(session)
     session.run(
-        'pytest',
+        'python', '-m', 'pytest',
         'benchmarks/benchmark_radcad.py',
         f'--benchmark-save=py{session.python}',
     )

tests/test_engine.py

@@ -1,6 +1,17 @@
 from radcad import Model, Simulation, Experiment
+from radcad.engine import Engine, Backend
 from tests.test_cases import basic
 
+def test_radcad_backend_env_sets_default(monkeypatch):
+    monkeypatch.setenv('RADCAD_BACKEND', 'SINGLE_PROCESS')
+    assert Engine().backend == Backend.SINGLE_PROCESS
+
+
+def test_radcad_backend_env_overrides_explicit_backend(monkeypatch):
+    monkeypatch.setenv('RADCAD_BACKEND', 'SINGLE_PROCESS')
+    assert Engine(backend=Backend.PATHOS).backend == Backend.SINGLE_PROCESS
+
+
 def test_run():
     states = basic.states
     state_update_blocks = basic.state_update_blocks

tests/test_examples.py

@@ -1,19 +1,85 @@
-import pytest
 import os
+import shutil
+import subprocess
+import sys
+import tempfile
+from pathlib import Path
+
+import pytest
+
+
+NOTEBOOK_TIMEOUT_SECONDS = 180
+
+
+def _tail(text, limit=4000):
+    if isinstance(text, bytes):
+        text = text.decode(errors="replace")
+    return text[-limit:] if text else ""
+
 
 def check_notebook(notebook):
-    result = os.popen(f"jupyter nbconvert --to script --execute --stdout {notebook} | ipython").read()
-    return "1" in result
+    notebook = Path(notebook)
+
+    with tempfile.TemporaryDirectory() as temp_dir:
+        temp_dir = Path(temp_dir)
+        work_dir = temp_dir / notebook.parent.name
+        shutil.copytree(notebook.parent, work_dir)
+        output_dir = temp_dir / "executed"
+        output_dir.mkdir()
+        notebook = work_dir / notebook.name
+
+        env = os.environ.copy()
+        # Force notebooks to single-process execution. Windows multiprocessing
+        # spawn cannot import notebook-defined functions, and PATHOS/dill has
+        # historically hit recursion/stack limits with notebook globals on CI.
+        env["RADCAD_BACKEND"] = "SINGLE_PROCESS"
+        command = [
+            sys.executable,
+            "-m",
+            "jupyter",
+            "nbconvert",
+            "--to",
+            "notebook",
+            "--execute",
+            f"--ExecutePreprocessor.timeout={NOTEBOOK_TIMEOUT_SECONDS}",
+            "--ExecutePreprocessor.kernel_name=python3",
+            "--output-dir",
+            output_dir,
+            str(notebook),
+        ]
+        try:
+            result = subprocess.run(
+                command,
+                capture_output=True,
+                text=True,
+                timeout=NOTEBOOK_TIMEOUT_SECONDS,
+                env=env,
+            )
+        except subprocess.TimeoutExpired as exc:
+            pytest.fail(
+                f"Notebook timed out after {NOTEBOOK_TIMEOUT_SECONDS}s: {notebook}\n"
+                f"stdout:\n{_tail(exc.stdout)}\n"
+                f"stderr:\n{_tail(exc.stderr)}"
+            )
+
+    assert result.returncode == 0, (
+        f"Notebook failed: {notebook}\n"
+        f"stdout:\n{_tail(result.stdout)}\n"
+        f"stderr:\n{_tail(result.stderr)}"
+    )
+
 
 def test_game_of_life():
-    assert check_notebook("examples/game_of_life/game-of-life.ipynb")
+    check_notebook("examples/game_of_life/game-of-life.ipynb")
+
 
 def test_predator_prey_sd():
-    assert check_notebook("examples/predator_prey_sd/predator-prey-sd.ipynb")
+    check_notebook("examples/predator_prey_sd/predator-prey-sd.ipynb")
+
 
 def test_predator_prey_abm():
-    assert check_notebook("examples/predator_prey_abm/predator-prey-abm.ipynb")
+    check_notebook("examples/predator_prey_abm/predator-prey-abm.ipynb")
 
-def test_harmonic_oscillator():
-    assert check_notebook("examples/harmonic_oscillator/harmonic_oscillator.ipynb")
 
+def test_harmonic_oscillator():
+    check_notebook("examples/harmonic_oscillator/harmonic_oscillator.ipynb")