Add --config cli option

beets/ui/__init__.py

@@ -767,9 +767,15 @@ def _raw_main(args):
                       help="destination music directory")
     parser.add_option('-v', '--verbose', dest='verbose', action='store_true',
                       help='print debugging information')
+    parser.add_option('-c', '--config', dest='config',
+                      help='path to configuration file')
 
     # Parse the command-line!
     options, subcommand, suboptions, subargs = parser.parse_args(args)
+    if hasattr(options, 'config') and options.config != None:
+        config_path = options.config
+        del options.config
+        config.add_file(config_path)
     config.set_args(options)
 
     # Open library file.

beets/util/confit.py

@@ -687,6 +687,11 @@ class Configuration(RootView):
             os.makedirs(appdir)
         return appdir
 
+    def add_file(self, filename):
+        """Parses the file as YAML and adds it to the configuration sources
+        """
+        self.add(ConfigSource(load_yaml(filename), filename))
+
 class LazyConfig(Configuration):
     """A Configuration at reads files on demand when it is first
     accessed. This is appropriate for using as a global config object at

docs/reference/cli.rst

@@ -301,6 +301,7 @@ import ...``.
 * ``-d DIRECTORY``: specify the library root directory.
 * ``-v``: verbose mode; prints out a deluge of debugging information. Please use
   this flag when reporting bugs.
+* ``-c /path/to/file``: read the configuration from this file.
 
 
 .. only:: man

docs/reference/config.rst

@@ -13,6 +13,9 @@ every aspect of its operation. To configure beets, you'll edit a file called
 * If you prefer a different location, set the ``BEETSDIR`` environment variable
   to a path; beets will then look for a ``config.yaml`` in that directory.
 
+Additionally, you can specify a different configuration file to load by adding
+the ``--config /path/to/file`` option to the beets command line.
+
 The config file uses `YAML`_ syntax. You can use the full power of YAML, but
 most configuration options are simple key/value pairs. This means your config
 file will look like this::

test/test_ui.py

@@ -472,6 +472,7 @@ class ConfigTest(_common.TestCase):
         super(ConfigTest, self).setUp()
         self.io.install()
         self.test_cmd = ui.Subcommand('test', help='test')
+        self.test_cmd.func = lambda *_: None
         commands.default_commands.append(self.test_cmd)
     def tearDown(self):
         super(ConfigTest, self).tearDown()
@@ -516,6 +517,16 @@ class ConfigTest(_common.TestCase):
                 library: /xxx/yyy/not/a/real/path
             """, func)
 
+    def test_cli_config_option(self):
+        """Read config from file passed on the command line with
+        ``--config file``
+        """
+        config_path = os.path.join(self.temp_dir, 'config.yml')
+        with open(config_path, 'w') as file:
+            file.write('anoption: value')
+        ui.main(['--config', config_path, 'test'])
+        self.assertEqual(config['anoption'].get(), 'value')
+
     def test_replacements_parsed(self):
         def func(lib, opts, args):
             replacements = lib.replacements