feat: add test for handling read-only files in cmd_add

tests/basic/test_commands.py

@@ -537,6 +537,38 @@ class TestCommands(TestCase):
         commands.cmd_add("file.txt")
         self.assertEqual(coder.abs_fnames, set())
 
+    def test_cmd_add_read_only_file(self):
+        # Initialize the Commands and InputOutput objects
+        io = InputOutput(pretty=False, yes=True)
+        from aider.coders import Coder
+
+        coder = Coder.create(self.GPT35, None, io)
+        commands = Commands(io, coder)
+
+        # Create a test file
+        test_file = Path("test_read_only.txt")
+        test_file.write_text("Test content")
+
+        # Add the file as read-only
+        commands.cmd_read(str(test_file))
+
+        # Verify it's in abs_read_only_fnames
+        self.assertTrue(any(os.path.samefile(str(test_file.resolve()), fname) for fname in coder.abs_read_only_fnames))
+
+        # Mock the repo to simulate a tracked file
+        coder.repo = mock.MagicMock()
+        coder.repo.is_tracked_file.return_value = True
+
+        # Try to add the read-only file
+        commands.cmd_add(str(test_file))
+
+        # Verify it's now in abs_fnames and not in abs_read_only_fnames
+        self.assertTrue(any(os.path.samefile(str(test_file.resolve()), fname) for fname in coder.abs_fnames))
+        self.assertFalse(any(os.path.samefile(str(test_file.resolve()), fname) for fname in coder.abs_read_only_fnames))
+
+        # Clean up
+        test_file.unlink()
+
     def test_cmd_test_unbound_local_error(self):
         with ChdirTemporaryDirectory():
             io = InputOutput(pretty=False, yes=False)