restream_playout/tests/test_purity.py

from __future__ import annotations

import ast
import unittest
from pathlib import Path


class PurityTests(unittest.TestCase):
    def test_package_has_no_process_launching_calls(self) -> None:
        package = Path(__file__).parents[1] / "restream_playout"
        forbidden_imports = {"subprocess"}
        forbidden_calls = {"os.system", "os.popen", "subprocess.run", "subprocess.Popen", "subprocess.call"}
        violations: list[str] = []
        for path in package.glob("*.py"):
            tree = ast.parse(path.read_text(encoding="utf-8"), filename=str(path))
            for node in ast.walk(tree):
                if isinstance(node, ast.Import):
                    for name in node.names:
                        if name.name in forbidden_imports:
                            violations.append(f"{path.name}: imports {name.name}")
                elif isinstance(node, ast.ImportFrom) and node.module in forbidden_imports:
                    violations.append(f"{path.name}: imports from {node.module}")
                elif isinstance(node, ast.Call) and isinstance(node.func, ast.Attribute):
                    if isinstance(node.func.value, ast.Name):
                        call = f"{node.func.value.id}.{node.func.attr}"
                        if call in forbidden_calls:
                            violations.append(f"{path.name}: calls {call}")
        self.assertEqual(violations, [])