Add concurrency stress test and minor path typing

src/tests/test_concurrency_stress.py

@@ -0,0 +1,72 @@
+import sys
+from pathlib import Path
+from multiprocessing import Process, Queue
+from cryptography.fernet import Fernet
+import pytest
+
+sys.path.append(str(Path(__file__).resolve().parents[1]))
+
+from password_manager.encryption import EncryptionManager
+from password_manager.vault import Vault
+from password_manager.backup import BackupManager
+
+
+def _writer(key: bytes, dir_path: Path, loops: int, out: Queue) -> None:
+    try:
+        enc = EncryptionManager(key, dir_path)
+        vault = Vault(enc, dir_path)
+        for _ in range(loops):
+            data = vault.load_index()
+            data["counter"] = data.get("counter", 0) + 1
+            vault.save_index(data)
+    except Exception as e:  # pragma: no cover - capture for assertion
+        out.put(repr(e))
+
+
+def _reader(key: bytes, dir_path: Path, loops: int, out: Queue) -> None:
+    try:
+        enc = EncryptionManager(key, dir_path)
+        vault = Vault(enc, dir_path)
+        for _ in range(loops):
+            vault.load_index()
+    except Exception as e:  # pragma: no cover - capture
+        out.put(repr(e))
+
+
+def _backup(dir_path: Path, loops: int, out: Queue) -> None:
+    try:
+        bm = BackupManager(dir_path)
+        for _ in range(loops):
+            bm.create_backup()
+    except Exception as e:  # pragma: no cover - capture
+        out.put(repr(e))
+
+
+@pytest.mark.parametrize("_", range(3))
+def test_concurrency_stress(tmp_path: Path, _):
+    key = Fernet.generate_key()
+    enc = EncryptionManager(key, tmp_path)
+    Vault(enc, tmp_path).save_index({"counter": 0})
+
+    q: Queue = Queue()
+    procs = [
+        Process(target=_writer, args=(key, tmp_path, 20, q)),
+        Process(target=_writer, args=(key, tmp_path, 20, q)),
+        Process(target=_reader, args=(key, tmp_path, 20, q)),
+        Process(target=_reader, args=(key, tmp_path, 20, q)),
+        Process(target=_backup, args=(tmp_path, 20, q)),
+    ]
+
+    for p in procs:
+        p.start()
+    for p in procs:
+        p.join()
+
+    errors = []
+    while not q.empty():
+        errors.append(q.get())
+
+    assert not errors
+
+    vault = Vault(EncryptionManager(key, tmp_path), tmp_path)
+    assert isinstance(vault.load_index(), dict)