From fda9a313a6ac14ab1fbb27b10931afa8159984a3 Mon Sep 17 00:00:00 2001
From: Adam Turner <9087854+aa-turner@users.noreply.github.com>
Date: Tue, 9 Jan 2024 00:31:04 +0000
Subject: [PATCH] Extract sub-functions from ``Theme.__init__()``

---
 sphinx/theming.py | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/sphinx/theming.py b/sphinx/theming.py
index 4172f17965f..9526ca41b14 100644
--- a/sphinx/theming.py
+++ b/sphinx/theming.py
@@ -49,6 +49,15 @@ def _extract_zip(filename: str, target_dir: str, /) -> None:
                 fp.write(archive.read(name))
 
 
+def _load_theme_conf(theme_dir: os.PathLike[str] | str) -> configparser.RawConfigParser:
+    c = configparser.RawConfigParser()
+    config_file_path = path.join(theme_dir, _THEME_CONF)
+    if not os.path.isfile(config_file_path):
+        raise ThemeError(__('theme configuration file %r not found') % config_file_path)
+    c.read(config_file_path, encoding='utf-8')
+    return c
+
+
 class Theme:
     """A Theme is a set of HTML templates and configurations.
 
@@ -69,11 +78,7 @@ def __init__(self, name: str, theme_path: str, theme_factory: HTMLThemeFactory)
             self._theme_dir = path.join(self._root_dir, name)
             _extract_zip(theme_path, self._theme_dir)
 
-        self.config = configparser.RawConfigParser()
-        config_file_path = path.join(self._theme_dir, _THEME_CONF)
-        if not os.path.isfile(config_file_path):
-            raise ThemeError(__('theme configuration file %r not found') % config_file_path)
-        self.config.read(config_file_path, encoding='utf-8')
+        self.config = _load_theme_conf(self._theme_dir)
 
         try:
             inherit = self.config.get('theme', 'inherit')
@@ -81,7 +86,14 @@ def __init__(self, name: str, theme_path: str, theme_factory: HTMLThemeFactory)
             raise ThemeError(__('theme %r doesn\'t have "theme" setting') % name) from exc
         except configparser.NoOptionError as exc:
             raise ThemeError(__('theme %r doesn\'t have "inherit" setting') % name) from exc
-
+        self._load_ancestor_theme(inherit, theme_factory, name)
+
+    def _load_ancestor_theme(
+        self,
+        inherit: str,
+        theme_factory: HTMLThemeFactory,
+        name: str,
+    ) -> None:
         if inherit != 'none':
             try:
                 self._base = theme_factory.create(inherit)