Add config.configdir and config.datadir to config API.

Fixes #1419

doc/help/configuring.asciidoc

@@ -225,6 +225,23 @@ that via `import utils` as well.
 While it's in some cases possible to import code from the qutebrowser
 installation, doing so is unsupported and discouraged.
 
+Getting the config directory
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If you need to get the qutebrowser config directory, you can do so by reading
+`config.configdir`. Similarily, you can get the qutebrowser data directory via
+`config.datadir`.
+
+This gives you a https://docs.python.org/3/library/pathlib.html[`pathlib.Path`
+object], on which you can use `/` to add more directory parts, or `str(...)` to
+get a string:
+
+.config.py:
+[source,python]
+----
+print(str(config.configdir / 'config.py')
+----
+
 Handling errors
 ~~~~~~~~~~~~~~~
 

qutebrowser/config/configfiles.py

@@ -19,6 +19,7 @@
 
 """Configuration files residing on disk."""
 
+import pathlib
 import types
 import os.path
 import sys
@@ -177,6 +178,8 @@ class ConfigAPI:
         _keyconfig: The KeyConfig object.
         load_autoconfig: Whether autoconfig.yml should be loaded.
         errors: Errors which occurred while setting options.
+        configdir: The qutebrowser config directory, as pathlib.Path.
+        datadir: The qutebrowser data directory, as pathlib.Path.
     """
 
     def __init__(self, conf, keyconfig):
@@ -184,6 +187,8 @@ class ConfigAPI:
         self._keyconfig = keyconfig
         self.load_autoconfig = True
         self.errors = []
+        self.configdir = pathlib.Path(standarddir.config())
+        self.datadir = pathlib.Path(standarddir.data())
 
     @contextlib.contextmanager
     def _handle_error(self, action, name):

tests/unit/config/test_configfiles.py

@@ -236,7 +236,7 @@ class TestConfigPyModules:
     pytestmark = pytest.mark.usefixtures('config_stub', 'key_config_stub')
 
     @pytest.fixture
-    def confpy(self, tmpdir):
+    def confpy(self, tmpdir, config_tmpdir, data_tmpdir):
         return ConfPy(tmpdir)
 
     @pytest.fixture
@@ -303,7 +303,7 @@ class TestConfigPy:
     pytestmark = pytest.mark.usefixtures('config_stub', 'key_config_stub')
 
     @pytest.fixture
-    def confpy(self, tmpdir):
+    def confpy(self, tmpdir, config_tmpdir, data_tmpdir):
         return ConfPy(tmpdir)
 
     def test_assertions(self, confpy):
@@ -312,6 +312,14 @@ class TestConfigPy:
         with pytest.raises(AssertionError):
             confpy.read()  # no errors=True so it gets raised
 
+    @pytest.mark.parametrize('what', ['configdir', 'datadir'])
+    def test_getting_dirs(self, confpy, what):
+        confpy.write('import pathlib',
+                     'directory = config.{}'.format(what),
+                     'assert isinstance(directory, pathlib.Path)',
+                     'assert directory.exists()')
+        confpy.read()
+
     @pytest.mark.parametrize('line', [
         'c.colors.hints.bg = "red"',
         'config.set("colors.hints.bg", "red")',
@@ -373,17 +381,18 @@ class TestConfigPy:
         assert config.instance._values['aliases']['foo'] == 'message-info foo'
         assert config.instance._values['aliases']['bar'] == 'message-info bar'
 
-    def test_reading_default_location(self, config_tmpdir):
+    def test_reading_default_location(self, config_tmpdir, data_tmpdir):
         (config_tmpdir / 'config.py').write_text(
             'c.colors.hints.bg = "red"', 'utf-8')
         configfiles.read_config_py()
         assert config.instance._values['colors.hints.bg'] == 'red'
 
-    def test_reading_missing_default_location(self, config_tmpdir):
+    def test_reading_missing_default_location(self, config_tmpdir,
+                                              data_tmpdir):
         assert not (config_tmpdir / 'config.py').exists()
         configfiles.read_config_py()  # Should not crash
 
-    def test_oserror(self, tmpdir):
+    def test_oserror(self, tmpdir, data_tmpdir, config_tmpdir):
         with pytest.raises(configexc.ConfigFileErrors) as excinfo:
             configfiles.read_config_py(str(tmpdir / 'foo'))