Add memfs unit tests

1 files changed, 39 insertions, 0 deletions

diff --git a/tests/test_memfs.py b/tests/test_memfs.py
new file mode 100644
index 0000000..128530a
--- /dev/null
+++ b/tests/test_memfs.py
@@ -0,0 +1,39 @@
+import logging
+from concurrent.futures import ThreadPoolExecutor
+from unittest import TestCase, mock
+from uuid import uuid4
+
+from snekbox.memfs import MemFS
+
+UUID_TEST = uuid4()
+
+
+def get_memfs_with_context():
+    return MemFS(10).__enter__()
+
+
+class NsJailTests(TestCase):
+    def setUp(self):
+        super().setUp()
+        self.logger = logging.getLogger("snekbox.memfs")
+        self.logger.setLevel(logging.WARNING)
+
+    @mock.patch("snekbox.memfs.uuid4", lambda: UUID_TEST)
+    def test_assignment_thread_safe(self):
+        """Test concurrent mounting works in multi-thread environments."""
+        # Concurrently create MemFS in threads, check only 1 can be created
+        # Others should result in RuntimeError
+        with ThreadPoolExecutor() as pool:
+            memfs: MemFS | None = None
+            futures = [pool.submit(get_memfs_with_context) for _ in range(8)]
+            for future in futures:
+                # We should have exactly one result and all others RuntimeErrors
+                if err := future.exception():
+                    self.assertIsInstance(err, RuntimeError)
+                else:
+                    self.assertIsNone(memfs)
+                    memfs = future.result()
+
+            # Original memfs should still exist afterwards
+            self.assertIsInstance(memfs, MemFS)
+            self.assertTrue(memfs.path.exists())