Add unset property option

docs/topic/tljh-config.rst

@@ -22,8 +22,8 @@ You can run ``tljh-config`` in two ways:
 .. _tljh-set:
 
 
-Set a configuration property
-============================
+Set / Unset a configuration property
+====================================
 
 TLJH's configuration is organized in a nested tree structure. You can
 set a particular property with the following command:
@@ -50,6 +50,17 @@ do so with the following:
 
 This can only set string and numerical properties, not lists.
 
+To unset a configuration property you can use the following command:
+
+.. code-block:: bash
+
+   sudo tljh-config unset <property-path>
+
+Unsetting a configuration property removes the property from the configuration
+file. If what you want is only to change the property's value, you should use
+``set`` and overwrite it with the desired value.
+
+
 Some of the existing ``<property-path>`` are listed below by categories:
 
 

tests/test_config.py

@@ -58,6 +58,57 @@ def test_set_overwrite():
     assert new_conf == {'a': 'hi'}
 
 
+def test_unset_no_mutate():
+    conf = {'a': 'b'}
+
+    new_conf = config.unset_item_from_config(conf, 'a')
+    assert conf == {'a': 'b'}
+
+
+def test_unset_one_level():
+    conf = {'a': 'b'}
+
+    new_conf = config.unset_item_from_config(conf, 'a')
+    assert new_conf == {}
+
+
+def test_unset_multi_level():
+    conf = {
+        'a': {'b': 'c', 'd': 'e'},
+        'f': 'g'
+    }
+
+    new_conf = config.unset_item_from_config(conf, 'a.b')
+    assert new_conf == {
+        'a': {'d': 'e'},
+        'f': 'g'
+    }
+    new_conf = config.unset_item_from_config(new_conf, 'a.d')
+    assert new_conf == {'f': 'g'}
+    new_conf = config.unset_item_from_config(new_conf, 'f')
+    assert new_conf == {}
+
+
+def test_unset_and_clean_empty_configs():
+    conf = {
+        'a': {'b': {'c': {'d': {'e': 'f'}}}}
+    }
+
+    new_conf = config.unset_item_from_config(conf, 'a.b.c.d.e')
+    assert new_conf == {}
+
+
+def test_unset_config_error():
+    with pytest.raises(ValueError):
+        config.unset_item_from_config({}, 'a')
+
+    with pytest.raises(ValueError):
+        config.unset_item_from_config({'a': 'b'}, 'b')
+
+    with pytest.raises(ValueError):
+        config.unset_item_from_config({'a': {'b': 'c'}}, 'a.z')
+
+
 def test_add_to_config_one_level():
     conf = {}
 
@@ -161,6 +212,18 @@ def test_cli_set_int(tljh_dir):
     assert cfg['https']['port'] == 123
 
 
+def test_cli_unset(tljh_dir):
+    config.main(["set", "foo.bar", "1"])
+    config.main(["set", "foo.bar2", "2"])
+    cfg = configurer.load_config()
+    assert cfg['foo'] == {'bar': 1, 'bar2': 2}
+
+    config.main(["unset", "foo.bar"])
+    cfg = configurer.load_config()
+
+    assert cfg['foo'] == {'bar2': 2}
+
+
 def test_cli_add_float(tljh_dir):
     config.main(["add-item", "foo.bar", "1.25"])
     cfg = configurer.load_config()

tljh/config.py

@@ -61,6 +61,50 @@ def set_item_in_config(config, property_path, value):
 
     return config_copy
 
+def unset_item_from_config(config, property_path):
+    """
+    Unset key at property_path in config & return new config.
+
+    config is not mutated.
+
+    property_path is a series of dot separated values.
+    """
+    path_components = property_path.split('.')
+
+    # Mutate a copy of the config, not config itself
+    cur_part = config_copy = deepcopy(config)
+
+    def remove_empty_configs(configuration, path):
+        """
+        Delete the keys that hold an empty dict.
+
+        This might happen when we delete a config property
+        that has no siblings from a multi-level config.
+        """
+        if not path:
+            return configuration
+        conf_iter = configuration
+        for cur_path in path:
+            if conf_iter[cur_path] == {}:
+                del conf_iter[cur_path]
+                remove_empty_configs(configuration, path[:-1])
+            else:
+                conf_iter = conf_iter[cur_path]
+
+    for i, cur_path in enumerate(path_components):
+        if i == len(path_components) - 1:
+            if cur_path not in cur_part:
+                raise ValueError(f'{property_path} does not exist in config!')
+            del cur_part[cur_path]
+            remove_empty_configs(config_copy, path_components[:-1])
+            break
+        else:
+            if cur_path not in cur_part:
+                raise ValueError(f'{property_path} does not exist in config!')
+            cur_part = cur_part[cur_path]
+
+    return config_copy
+
 def add_item_to_config(config, property_path, value):
     """
     Add an item to a list in config.
@@ -97,7 +141,7 @@ def remove_item_from_config(config, property_path, value):
     cur_part = config_copy = deepcopy(config)
     for i, cur_path in enumerate(path_components):
         if i == len(path_components) - 1:
-            # Final component, it must be a list and we append to it
+            # Final component, it must be a list and we delete from it
             if cur_path not in cur_part or not _is_list(cur_part[cur_path]):
                 raise ValueError(f'{property_path} is not a list')
             cur_part = cur_part[cur_path]
@@ -141,6 +185,24 @@ def set_config_value(config_path, key_path, value):
         yaml.dump(config, f)
 
 
+def unset_config_value(config_path, key_path):
+    """
+    Unset key at key_path in config_path
+    """
+    # FIXME: Have a file lock here
+    # FIXME: Validate schema here
+    try:
+        with open(config_path) as f:
+            config = yaml.load(f)
+    except FileNotFoundError:
+        config = {}
+
+    config = unset_item_from_config(config, key_path)
+
+    with open(config_path, 'w') as f:
+        yaml.dump(config, f)
+
+
 def add_config_value(config_path, key_path, value):
     """
     Add value to list at key_path
@@ -260,6 +322,15 @@ def main(argv=None):
         help='Show current configuration'
     )
 
+    unset_parser = subparsers.add_parser(
+        'unset',
+        help='Unset a configuration property'
+    )
+    unset_parser.add_argument(
+        'key_path',
+        help='Dot separated path to configuration key to unset'
+    )
+
     set_parser = subparsers.add_parser(
         'set',
         help='Set a configuration property'
@@ -317,6 +388,8 @@ def main(argv=None):
         show_config(args.config_path)
     elif args.action == 'set':
         set_config_value(args.config_path, args.key_path, parse_value(args.value))
+    elif args.action == 'unset':
+        unset_config_value(args.config_path, args.key_path)
     elif args.action == 'add-item':
         add_config_value(args.config_path, args.key_path, parse_value(args.value))
     elif args.action == 'remove-item':