Admit optional CLI arg specifying config file path

mackup/config.py

@@ -1,6 +1,6 @@
 """Package used to manage the .mackup.cfg config file."""
 
-import os
+import logging
 import os.path
 
 from .constants import (
@@ -28,22 +28,23 @@
     import ConfigParser as configparser
 
 
+logger = logging.getLogger(__name__)
+
+
 class Config(object):
 
     """The Mackup Config class."""
 
-    def __init__(self, filename=None):
+    def __init__(self, config_path=None):
         """
         Create a Config instance.
 
         Args:
-            filename (str): Optional filename of the config file. If empty,
-                            defaults to MACKUP_CONFIG_FILE
+            config_path (str): Optional path to a mackup config file.
         """
-        assert isinstance(filename, str) or filename is None
 
         # Initialize the parser
-        self._parser = self._setup_parser(filename)
+        self._parser = self._setup_parser(config_path)
 
         # Do we have an old config file ?
         self._warn_on_old_config()
@@ -131,24 +132,62 @@ def apps_to_sync(self):
         """
         return set(self._apps_to_sync)
 
-    def _setup_parser(self, filename=None):
+    @classmethod
+    def _resolve_config_path(cls, filename=None):
+        """
+        Resolve the optional, user-supplied path to a Mackup config file. If
+        none supplied, defaults to looking for MACKUP_CONFIG_FILE in the user's
+        home directory.
+
+        Returns:
+            str, or None if filename doesn't exist
+        """
+        file_exists = lambda p: os.path.isfile(p)
+
+        if filename is None:
+            # use $HOME, instead of pathlib.Path.home, to preserve existing behavior
+            # (some unit tests rely on monkeypatching that value)
+            path = os.path.abspath(os.path.join(os.environ["HOME"], MACKUP_CONFIG_FILE))
+            if file_exists(path):
+                return path
+            else:
+                logger.warning(
+                    "Default config file {} not found, and no alternative filename given.".format(
+                        path
+                    )
+                )
+                return None
+
+        possible_paths = [
+            os.path.expanduser(filename),
+            os.path.join(os.environ["HOME"], filename),
+            os.path.join(os.getcwd(), filename),
+        ]
+        # iter() call for Python2 compatibility (filter() returns a list in Python2)
+        path = os.path.abspath(next(iter(filter(file_exists, possible_paths)), None))
+        if path:
+            return path
+        else:
+            logger.warning(
+                "Config file {} not found! Tried paths: {}".format(
+                    filename, possible_paths
+                )
+            )
+            return None
+
+    def _setup_parser(self, config_path=None):
         """
         Configure the ConfigParser instance the way we want it.
 
         Args:
-            filename (str) or None
-
+            config_path (str): Optional path to a mackup config file.
         Returns:
             SafeConfigParser
         """
-        assert isinstance(filename, str) or filename is None
-
-        # If we are not overriding the config filename
-        if not filename:
-            filename = MACKUP_CONFIG_FILE
-
         parser = configparser.SafeConfigParser(allow_no_value=True)
-        parser.read(os.path.join(os.path.join(os.environ["HOME"], filename)))
+        # call will return None if config_path doesn't exist
+        path = self._resolve_config_path(config_path) or ""
+        parser.read(path)
 
         return parser
 

mackup/mackup.py

@@ -19,9 +19,9 @@ class Mackup(object):
 
     """Main Mackup class."""
 
-    def __init__(self):
+    def __init__(self, filename=None):
         """Mackup Constructor."""
-        self._config = config.Config()
+        self._config = config.Config(filename)
 
         self.mackup_folder = self._config.fullpath
         self.temp_folder = tempfile.mkdtemp(prefix="mackup_tmp_")

mackup/main.py

@@ -13,12 +13,13 @@
   mackup --version
 
 Options:
-  -h --help     Show this screen.
-  -f --force    Force every question asked to be answered with "Yes".
-  -r --root     Allow mackup to be run as superuser.
-  -n --dry-run  Show steps without executing.
-  -v --verbose  Show additional details.
-  --version     Show version.
+  -h --help               Show this screen.
+  -c FILE --config=FILE   Configuration file to use.
+  -f --force              Force every question asked to be answered with "Yes".
+  -r --root               Allow mackup to be run as superuser.
+  -n --dry-run            Show steps without executing.
+  -v --verbose            Show additional details.
+  --version               Show version.
 
 Modes of action:
  1. list: display a list of all supported applications.
@@ -63,7 +64,7 @@ def main():
     # Get the command line arg
     args = docopt(__doc__, version="Mackup {}".format(VERSION))
 
-    mckp = Mackup()
+    mckp = Mackup(args["--config"])
     app_db = ApplicationsDatabase()
 
     def printAppHeader(app_name):

tests/config_tests.py

@@ -1,20 +1,22 @@
 import unittest
 import os.path
+import tempfile
 
 from mackup.constants import (
     ENGINE_DROPBOX,
     ENGINE_GDRIVE,
     ENGINE_COPY,
     ENGINE_ICLOUD,
     ENGINE_FS,
+    MACKUP_CONFIG_FILE,
 )
 from mackup.config import Config, ConfigError
 
 
 class TestConfig(unittest.TestCase):
     def setUp(self):
         realpath = os.path.dirname(os.path.realpath(__file__))
-        os.environ["HOME"] = os.path.join(realpath, "fixtures")
+        self.mock_home = os.environ["HOME"] = os.path.join(realpath, "fixtures")
 
     def test_config_no_config(self):
         cfg = Config()
@@ -232,3 +234,35 @@ def test_config_apps_to_ignore_and_sync(self):
 
     def test_config_old_config(self):
         self.assertRaises(SystemExit, Config, "mackup-old-config.cfg")
+
+    def test_resolve_config_path_returns_default_path_if_file_exists(self):
+        pass
+
+    def test_resolve_config_path_returns_none_if_default_config_file_nonexistent(self):
+        resolved_path = Config._resolve_config_path()
+
+        assert resolved_path is None
+
+    def test_resolve_config_path_performs_tilde_expansion(self):
+        with tempfile.NamedTemporaryFile(dir=os.path.expanduser("~")) as mock_cfg_file:
+            mock_filename = os.path.basename(mock_cfg_file.name)
+            filename = os.path.join("~", mock_filename)
+            resolved_path = Config._resolve_config_path(filename)
+
+            assert resolved_path == mock_cfg_file.name
+
+    def test_resolve_config_path_relative_to_home_dir(self):
+        with tempfile.NamedTemporaryFile(dir=self.mock_home) as mock_cfg_file:
+            mock_filename = os.path.basename(mock_cfg_file.name)
+            resolved_path = Config._resolve_config_path(mock_filename)
+
+            assert resolved_path == mock_cfg_file.name
+
+    def test_resolves_config_path_relative_to_cwd(self):
+        cwd = os.getcwd()
+        with tempfile.NamedTemporaryFile(dir=cwd) as mock_cfg_file:
+            mock_path = mock_cfg_file.name
+            mock_filename = os.path.basename(mock_cfg_file.name)
+            resolved_path = Config._resolve_config_path(mock_filename)
+
+            assert resolved_path == mock_path