Support (part of) the XDG Base Directory Specification (#920)

On Unix-like systems, the configuration file now lives in
$XDG_CONFIG_HOME/httpie/ by default, not ~/.httpie/ (the behaviour on
Windows is unchanged). The previous location is still checked, in order
to support existing installations.

Searching $XDG_CONFIG_DIRS is still not supported.

Fixes #145; supersedes #436.

README.rst

@@ -1691,8 +1691,11 @@ but you can create it manually.
 Config file directory
 ---------------------
 
-The default location of the configuration file is ``~/.httpie/config.json``
-(or ``%APPDATA%\httpie\config.json`` on Windows).
+The default location of the configuration file on most platforms is
+``$XDG_CONFIG_HOME/httpie/config.json`` (defaulting to
+``~/.config/httpie/config.json``). For backwards compatibility, if the directory
+``~/.httpie`` exists, the configuration file there will be used instead. On
+Windows, the config file is located at ``%APPDATA%\httpie\config.json``.
 
 The config directory can be changed by setting the ``$HTTPIE_CONFIG_DIR``
 environment variable:

httpie/config.py

@@ -8,11 +8,28 @@ from httpie import __version__
 from httpie.compat import is_windows
 
 
-DEFAULT_CONFIG_DIR = Path(os.environ.get(
-    'HTTPIE_CONFIG_DIR',
-    os.path.expanduser('~/.httpie') if not is_windows else
-    os.path.expandvars(r'%APPDATA%\\httpie')
-))
+def get_default_config_dir() -> Path:
+    """Return the path to the httpie configuration directory.
+
+    This directory isn't guaranteed to exist, and nor are any of its
+    ancestors.
+    """
+    env_config_dir = os.environ.get('HTTPIE_CONFIG_DIR')
+    if env_config_dir:
+        return Path(env_config_dir)
+    if is_windows:
+        return Path(os.path.expandvars(r'%APPDATA%\httpie'))
+    legacy_config_dir = os.path.expanduser('~/.httpie')
+    if os.path.exists(legacy_config_dir):
+        return Path(legacy_config_dir)
+    xdg_config_dir = os.environ.get('XDG_CONFIG_HOME')
+    if not xdg_config_dir or not os.path.isabs(xdg_config_dir):
+        xdg_config_dir = os.path.expanduser('~/.config')
+    httpie_config_dir = os.path.join(xdg_config_dir, 'httpie')
+    return Path(httpie_config_dir)
+
+
+DEFAULT_CONFIG_DIR = get_default_config_dir()
 
 
 class ConfigFileError(Exception):

tests/test_config.py

@@ -1,7 +1,10 @@
+import os.path
+from pathlib import Path
+
 import pytest
 
 from httpie.compat import is_windows
-from httpie.config import Config
+from httpie.config import Config, get_default_config_dir
 from utils import HTTP_OK, MockEnvironment, http
 
 
@@ -48,3 +51,40 @@ def test_default_options_overwrite(httpbin):
     assert r.json['json'] == {
         "foo": "bar"
     }
+
+
+@pytest.mark.skipif(is_windows, reason='XDG_CONFIG_HOME is only supported on *nix')
+def test_config_file_location_xdg(monkeypatch, tmp_path):
+    monkeypatch.delenv('HTTPIE_CONFIG_DIR', raising=False)
+    home = tmp_path.absolute().as_posix()
+    monkeypatch.setenv('HOME', home)
+    xdg_config_home = tmp_path.joinpath("different_config")
+    os.mkdir(xdg_config_home)
+    monkeypatch.setenv('XDG_CONFIG_HOME', xdg_config_home.absolute().as_posix())
+    assert get_default_config_dir() == xdg_config_home.joinpath('httpie')
+    monkeypatch.delenv('XDG_CONFIG_HOME')
+    # NB: this should be true even though .config doesn't exist.
+    assert get_default_config_dir() == tmp_path.joinpath('.config', 'httpie')
+    monkeypatch.setenv('XDG_CONFIG_HOME', 'some/nonabsolute/path')
+    assert get_default_config_dir() == tmp_path.joinpath('.config', 'httpie')
+
+
+@pytest.mark.skipif(is_windows, reason='legacy config file location is only checked on *nix')
+def test_config_file_location_legacy(monkeypatch, tmp_path):
+    monkeypatch.delenv('HTTPIE_CONFIG_DIR', raising=False)
+    home = tmp_path.absolute().as_posix()
+    monkeypatch.setenv('HOME', home)
+    os.mkdir(tmp_path.joinpath('.httpie'))
+    assert get_default_config_dir() == tmp_path.joinpath('.httpie')
+
+
+@pytest.mark.skipif(not is_windows, reason='windows-only')
+def test_config_file_location_windows(monkeypatch):
+    monkeypatch.delenv('HTTPIE_CONFIG_DIR', raising=False)
+    assert get_default_config_dir() == Path(os.path.expandvars(r'%APPDATA%\httpie'))
+
+
+def test_config_file_location_custom(monkeypatch, tmp_path):
+    httpie_config_dir = tmp_path.joinpath('custom', 'directory')
+    monkeypatch.setenv('HTTPIE_CONFIG_DIR', str(httpie_config_dir.absolute()))
+    assert get_default_config_dir() == httpie_config_dir