Override particular configuration options from the command-line via "--override" flag (#268).

tests/integration/config/test_override.py

@@ -0,0 +1,40 @@
+import pytest
+
+from borgmatic.config import override as module
+
+
+@pytest.mark.parametrize(
+    'value,expected_result',
+    (
+        ('thing', 'thing'),
+        ('33', 33),
+        ('33b', '33b'),
+        ('true', True),
+        ('false', False),
+        ('[foo]', ['foo']),
+        ('[foo, bar]', ['foo', 'bar']),
+    ),
+)
+def test_convert_value_type_coerces_values(value, expected_result):
+    assert module.convert_value_type(value) == expected_result
+
+
+def test_apply_overrides_updates_config():
+    raw_overrides = [
+        'section.key=value1',
+        'other_section.thing=value2',
+        'section.nested.key=value3',
+        'new.foo=bar',
+    ]
+    config = {
+        'section': {'key': 'value', 'other': 'other_value'},
+        'other_section': {'thing': 'thing_value'},
+    }
+
+    module.apply_overrides(config, raw_overrides)
+
+    assert config == {
+        'section': {'key': 'value1', 'other': 'other_value', 'nested': {'key': 'value3'}},
+        'other_section': {'thing': 'value2'},
+        'new': {'foo': 'bar'},
+    }