1 files changed, 111 insertions, 0 deletions
diff --git a/tests/test_tarfile.py b/tests/test_tarfile.py
new file mode 100644
index 00000000..12fd9b26
--- /dev/null
+++ b/tests/test_tarfile.py
@@ -0,0 +1,111 @@
+#!/usr/bin/python3
+#
+# Copyright (C) 2025 Canonical Ltd.
+#
+# Copying and distribution of this file, with or without modification,
+# are permitted in any medium without royalty provided the copyright
+# notice and this notice are preserved.
+"""Unit tests for verifying the correctness of tarfile management used in apt.debfile."""
+
+import os
+import resource
+import sys
+import unittest
+from collections.abc import Callable
+from typing import override
+
+import apt_inst
+from test_all import get_library_dir
+from testcommon import TestCase
+
+libdir = get_library_dir()
+if libdir:
+    sys.path.insert(0, libdir)
+
+
+class TestTarfile(TestCase):
+    """test the tarfile"""
+
+    # Large tarfile with single member called 'large_member'
+    TEST_LARGE_TARFILE: str = "./data/misc/large_tar.zst"
+    TEST_LARGE_TARFILE_MEMBER: str = "large_member"
+
+    # Setting resource limit to trigger MemoryError for large files
+    VR_MEM_LIMIT_HARD: int = 2**31
+    VR_MEM_LIMIT_SOFT: int = VR_MEM_LIMIT_HARD
+    # resource.setrlimit(resource.RLIMIT_AS, (VR_MEM_LIMIT_SOFT, VR_MEM_LIMIT_HARD))
+
+    tarfile: apt_inst.TarFile | None = None
+
+    @classmethod
+    @override
+    def setUpClass(cls):
+        super().setUpClass()
+        resource.setrlimit(
+            resource.RLIMIT_AS, (cls.VR_MEM_LIMIT_SOFT, cls.VR_MEM_LIMIT_HARD)
+        )
+
+    def _make_large_tarfile(self) -> apt_inst.TarFile:
+        """
+        Helper method to create a TarFile instance for the large tarfile.
+
+        Having one shared class members for the tarfile introduces test errors
+        during building. This method ensures that each test gets a fresh
+        instance of the TarFile.
+
+        """
+        return apt_inst.TarFile(self.TEST_LARGE_TARFILE, comp="zstd")
+
+    @override
+    def setUp(self):
+        super().setUp()
+        self.tarfile = self._make_large_tarfile()
+
+    def _collect_filenames_callback(
+        self, files: list[str]
+    ) -> Callable[[apt_inst.TarMember, bytes], None]:
+        """Helper method to collect filenames from tarfile.go callback."""
+        return lambda item, data: files.append(item.name)
+
+    def test_go_extract_data_large_file_oom(self):
+        assert self.tarfile is not None
+        files: list[str] = []
+        with self.assertRaises(MemoryError):
+            self.tarfile.go(
+                (self._collect_filenames_callback(files)),
+                self.TEST_LARGE_TARFILE_MEMBER,
+                True,
+            )
+        self.assertEqual(files, [])
+
+    def test_go_extract_false_large_file_no_oom(self):
+        assert self.tarfile is not None
+        files: list[str] = []
+        try:
+            self.tarfile.go(
+                self._collect_filenames_callback(files),
+                self.TEST_LARGE_TARFILE_MEMBER,
+                False,
+            )
+        except MemoryError:
+            self.fail(
+                "tarfile.go(...) raised MemoryError with extract_data set to False!"
+            )
+        self.assertEqual(files, [self.TEST_LARGE_TARFILE_MEMBER])
+
+    def test_go_skip_extract_large_file_if_not_specified(self):
+        assert self.tarfile is not None
+        files: list[str] = []
+        try:
+            self.tarfile.go(self._collect_filenames_callback(files), "", True)
+        except MemoryError:
+            self.fail(
+                "tarfile.go(...) raised MemoryError when no member was specified!"
+            )
+        self.assertEqual(files, [self.TEST_LARGE_TARFILE_MEMBER])
+
+
+if __name__ == "__main__":
+    # logging.basicConfig(level=logging.DEBUG)
+    os.chdir(os.path.dirname(__file__))
+    _ = unittest.main()