refactor: missing tests for settings cascade and override logic (#2287)

The `Settings.load()` method iterates through multiple configuration file paths and updates the internal `__dict__`, intending to override earlier default settings with later user-specific ones. This cascading logic is a core configuration feature but lacks explicit tests to guarantee that dictionary merging and overriding behave exactly as documented (e.g., ensuring a setting in `~/.maigret/settings.json` correctly overrides `resources/settings.json` without wiping out other keys).


Affected files: test_settings.py

tests/test_settings.py

@@ -0,0 +1,53 @@
+import unittest
+from unittest.mock import patch, mock_open
+
+from maigret.settings import Settings
+
+
+class TestSettings(unittest.TestCase):
+    @patch('json.load')
+    @patch('builtins.open', new_callable=mock_open)
+    def test_settings_cascade_and_override(self, mock_file, mock_json_load):
+        file1_data = {"timeout": 10, "retries_count": 3, "proxy_url": "http://proxy1"}
+        file2_data = {"timeout": 20, "recursive_search": True}
+        file3_data = {"proxy_url": "http://proxy3", "print_not_found": False}
+
+        mock_json_load.side_effect = [file1_data, file2_data, file3_data]
+
+        settings = Settings()
+        paths = ['file1.json', 'file2.json', 'file3.json']
+
+        was_inited, msg = settings.load(paths)
+
+        self.assertTrue(was_inited)
+        self.assertEqual(settings.retries_count, 3)
+        self.assertEqual(settings.timeout, 20)
+        self.assertTrue(settings.recursive_search)
+        self.assertEqual(settings.proxy_url, "http://proxy3")
+        self.assertFalse(settings.print_not_found)
+
+    @patch('builtins.open')
+    def test_settings_file_not_found(self, mock_open_func):
+        mock_open_func.side_effect = FileNotFoundError()
+
+        settings = Settings()
+        paths = ['nonexistent.json']
+
+        was_inited, msg = settings.load(paths)
+
+        self.assertFalse(was_inited)
+        self.assertIn('None of the default settings files found', msg)
+
+    @patch('json.load')
+    @patch('builtins.open', new_callable=mock_open)
+    def test_settings_invalid_json(self, mock_file, mock_json_load):
+        mock_json_load.side_effect = ValueError("Expecting value")
+
+        settings = Settings()
+        paths = ['invalid.json']
+
+        was_inited, msg = settings.load(paths)
+
+        self.assertFalse(was_inited)
+        self.assertIsInstance(msg, ValueError)
+        self.assertIn('Problem with parsing json contents', str(msg))