1 files changed, 104 insertions, 0 deletions
diff --git a/tests/test_backend.py b/tests/test_backend.py
new file mode 100644
index 0000000..69165f1
--- /dev/null
+++ b/tests/test_backend.py
@@ -0,0 +1,104 @@
+import tempfile
+import unittest
+from pathlib import Path
+
+from backend import config
+from backend.bundle import BundleManager
+from backend.patcher import PatchManager
+from backend.steam import SteamLibrary
+
+
+class BackendSafetyTests(unittest.TestCase):
+    def setUp(self):
+        self.temp_dir = tempfile.TemporaryDirectory()
+        root = Path(self.temp_dir.name)
+        self.home = root / "home"
+        self.plugin_dir = root / "plugin"
+        self.home.mkdir()
+        self.plugin_dir.mkdir()
+
+        bundle_path = self.home / "fgmod"
+        (bundle_path / "renames").mkdir(parents=True)
+        (bundle_path / "plugins").mkdir()
+        (bundle_path / "fsr4-rdna2-3").mkdir()
+        (bundle_path / "OptiScaler.dll").write_bytes(b"optiscaler")
+        (bundle_path / "renames" / "dxgi.dll").write_bytes(b"managed-proxy")
+        (bundle_path / "OptiScaler.ini").write_text("FGInput=auto\nFGOutput=auto\n", encoding="utf-8")
+        (bundle_path / "plugins" / "OptiPatcher.asi").write_bytes(b"plugin")
+        (bundle_path / "fsr4-rdna2-3" / "amd_fidelityfx_upscaler_dx12.dll").write_bytes(b"upscaler")
+
+        logger = lambda _message: None
+        bundle = BundleManager(self.home, self.plugin_dir, logger)
+        self.manager = PatchManager(self.home, bundle, SteamLibrary(self.home, logger), logger)
+        self.target = root / "game"
+        (self.target / "plugins").mkdir(parents=True)
+        (self.target / "plugins" / "keep.txt").write_text("user-owned", encoding="utf-8")
+        (self.target / "dxgi.dll").write_bytes(b"original-game-proxy")
+        (self.target / "OptiScaler.ini").write_text("FGInput=auto\nFGOutput=auto\nUserSetting=true\n", encoding="utf-8")
+
+    def tearDown(self):
+        self.temp_dir.cleanup()
+
+    def test_patch_and_unpatch_preserve_unowned_files(self):
+        result = self.manager.manual_patch_directory(str(self.target), "dxgi.dll", "rdna23-int8", "auto")
+        self.assertEqual(result["status"], "success")
+        self.assertTrue((self.target / "FRAMEGEN_PATCH").exists())
+        self.assertTrue((self.target / "dxgi.dll.b").exists())
+        self.assertTrue((self.target / "plugins" / "keep.txt").exists())
+
+        cleanup = self.manager.manual_unpatch_directory(str(self.target))
+        self.assertEqual(cleanup["status"], "success")
+        self.assertFalse((self.target / "FRAMEGEN_PATCH").exists())
+        self.assertEqual((self.target / "dxgi.dll").read_bytes(), b"original-game-proxy")
+        self.assertEqual((self.target / "plugins" / "keep.txt").read_text(encoding="utf-8"), "user-owned")
+        self.assertEqual(
+            (self.target / "OptiScaler.ini").read_text(encoding="utf-8"),
+            "FGInput=auto\nFGOutput=auto\nUserSetting=true\n",
+        )
+        self.assertFalse((self.target / "plugins" / "OptiPatcher.asi").exists())
+
+    def test_unpatch_refuses_modified_managed_file_and_keeps_marker(self):
+        result = self.manager.manual_patch_directory(str(self.target), "dxgi.dll", "rdna23-int8", "nukems")
+        self.assertEqual(result["status"], "success")
+        (self.target / "dxgi.dll").write_bytes(b"user-modified")
+
+        cleanup = self.manager.manual_unpatch_directory(str(self.target))
+        self.assertEqual(cleanup["status"], "error")
+        self.assertTrue((self.target / "FRAMEGEN_PATCH").exists())
+        self.assertEqual((self.target / "dxgi.dll").read_bytes(), b"user-modified")
+        self.assertTrue((self.target / "plugins" / "keep.txt").exists())
+
+    def test_appid_unpatch_propagates_cleanup_failure(self):
+        class FakeSteam:
+            def game_record(self, appid):
+                return {"appid": appid, "name": "Test Game", "install_path": str(self_target)}
+
+            def is_game_running(self, _game_info):
+                return False
+
+            def guess_patch_target(self, _game_info):
+                return self_target, None
+
+        self_target = self.target
+        self.manager.steam = FakeSteam()
+        result = self.manager.patch_game("123", "dxgi.dll", "", "rdna23-int8", "auto")
+        self.assertEqual(result["status"], "success")
+        (self.target / "dxgi.dll").write_bytes(b"modified after patch")
+
+        cleanup = self.manager.unpatch_game("123")
+        self.assertEqual(cleanup["status"], "error")
+        self.assertTrue((self.target / "FRAMEGEN_PATCH").exists())
+
+    def test_backend_configuration_is_explicit(self):
+        ini_file = self.target / "backend.ini"
+        ini_file.write_text("FGInput=auto\nFGOutput=auto\n", encoding="utf-8")
+        self.assertTrue(config.configure(ini_file, "nukems"))
+        self.assertIn("FGInput=nukems", ini_file.read_text(encoding="utf-8"))
+        self.assertIn("FGOutput=nukems", ini_file.read_text(encoding="utf-8"))
+        self.assertTrue(config.configure(ini_file, "auto"))
+        self.assertIn("FGInput=auto", ini_file.read_text(encoding="utf-8"))
+        self.assertIn("FGOutput=auto", ini_file.read_text(encoding="utf-8"))
+
+
+if __name__ == "__main__":
+    unittest.main()