Add negative test cases for path-traversal protection in update.retrieve()

tests/test_api.py

@@ -48,3 +48,39 @@ def test_retrieve(self, url: str, filename: str, is_tar: bool):
 
             file_count = len([f for f in pathlib.Path(tmpdir).iterdir() if f.is_file()])
             self.assertGreater(file_count, 0)
+
+    def _make_tarball_with_traversal(self, directory: str, filename: str, member_name: str) -> str:
+        """Create a tarball fixture whose sole member uses a path-traversal name."""
+        tarball_path = str(pathlib.Path(directory) / filename)
+        inner_content = b"malicious content"
+        buf = io.BytesIO(inner_content)
+        buf.seek(0)
+        with tarfile.open(tarball_path, "w") as tar:
+            info = tarfile.TarInfo(name=member_name)
+            info.size = len(inner_content)
+            tar.addfile(info, buf)
+        return tarball_path
+
+    def test_retrieve_path_traversal_raises(self):
+        """A tar member that escapes the target directory must raise ValueError."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            fake_path = self._make_tarball_with_traversal(
+                tmpdir, "traversal.tar", "../malicious.txt"
+            )
+            with patch(
+                "pyiri2016.api.update.wget.download", return_value=fake_path
+            ):
+                with self.assertRaises(ValueError):
+                    update.retrieve("http://example.com", "traversal.tar", directory=tmpdir)
+
+    def test_retrieve_absolute_path_in_tar_raises(self):
+        """A tar member with an absolute path that escapes the target directory must raise ValueError."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            fake_path = self._make_tarball_with_traversal(
+                tmpdir, "absolute.tar", "/etc/passwd"
+            )
+            with patch(
+                "pyiri2016.api.update.wget.download", return_value=fake_path
+            ):
+                with self.assertRaises(ValueError):
+                    update.retrieve("http://example.com", "absolute.tar", directory=tmpdir)