Raise ExtensionError from Config class instead application class

sphinx/application.py

@@ -29,9 +29,7 @@ from sphinx import package_dir, locale
 from sphinx.config import Config
 from sphinx.deprecation import RemovedInSphinx20Warning, RemovedInSphinx30Warning
 from sphinx.environment import BuildEnvironment
-from sphinx.errors import (
-    ApplicationError, ConfigError, ExtensionError, VersionRequirementError
-)
+from sphinx.errors import ApplicationError, ConfigError, VersionRequirementError
 from sphinx.events import EventManager
 from sphinx.locale import __
 from sphinx.registry import SphinxComponentRegistry
@@ -556,8 +554,6 @@ class Sphinx(object):
         """
         logger.debug('[app] adding config value: %r',
                      (name, default, rebuild) + ((types,) if types else ()))  # type: ignore
-        if name in self.config:
-            raise ExtensionError(__('Config value %r already present') % name)
         if rebuild in (False, True):
             rebuild = rebuild and 'env' or ''
         self.config.add(name, default, rebuild, types)

sphinx/config.py

@@ -19,7 +19,7 @@ from typing import Any, NamedTuple, Union
 from six import PY2, PY3, iteritems, string_types, binary_type, text_type, integer_types
 
 from sphinx.deprecation import RemovedInSphinx30Warning
-from sphinx.errors import ConfigError
+from sphinx.errors import ConfigError, ExtensionError
 from sphinx.locale import _, __
 from sphinx.util import logging
 from sphinx.util.i18n import format_date
@@ -347,7 +347,10 @@ class Config(object):
 
     def add(self, name, default, rebuild, types):
         # type: (unicode, Any, Union[bool, unicode], Any) -> None
-        self.values[name] = (default, rebuild, types)
+        if name in self.values:
+            raise ExtensionError(__('Config value %r already present') % name)
+        else:
+            self.values[name] = (default, rebuild, types)
 
     def filter(self, rebuild):
         # type: (Union[unicode, List[unicode]]) -> Iterator[ConfigValue]

sphinx/ext/autodoc/__init__.py

@@ -20,8 +20,8 @@ from docutils.statemachine import ViewList
 from six import iteritems, itervalues, text_type, class_types, string_types
 
 import sphinx
-from sphinx.application import ExtensionError
 from sphinx.deprecation import RemovedInSphinx20Warning
+from sphinx.errors import ExtensionError
 from sphinx.ext.autodoc.importer import mock, import_object, get_object_members
 from sphinx.ext.autodoc.importer import _MockImporter  # to keep compatibility  # NOQA
 from sphinx.ext.autodoc.inspector import format_annotation, formatargspec  # to keep compatibility  # NOQA

sphinx/ext/jsmath.py

@@ -15,7 +15,7 @@ from typing import TYPE_CHECKING
 from docutils import nodes
 
 import sphinx
-from sphinx.application import ExtensionError
+from sphinx.errors import ExtensionError
 from sphinx.ext.mathbase import get_node_equation_number
 from sphinx.ext.mathbase import setup_math as mathbase_setup
 from sphinx.locale import _

tests/roots/test-root/conf.py

@@ -12,7 +12,7 @@ from sphinx import addnodes
 sys.path.append(os.path.abspath('.'))
 
 extensions = ['sphinx.ext.autodoc', 'sphinx.ext.jsmath', 'sphinx.ext.todo',
-              'sphinx.ext.coverage', 'sphinx.ext.extlinks', 'ext']
+              'sphinx.ext.coverage', 'sphinx.ext.extlinks']
 
 jsmath_path = 'dummy.js'
 
@@ -65,8 +65,6 @@ man_pages = [
      'Georg Brandl and someone else', 1),
 ]
 
-value_from_conf_py = 84
-
 coverage_c_path = ['special/*.h']
 coverage_c_regexes = {'function': r'^PyAPI_FUNC\(.*\)\s+([^_][\w_]+)'}
 
@@ -104,7 +102,6 @@ class ClassDirective(Directive):
 def setup(app):
     import parsermod
 
-    app.add_config_value('value_from_conf_py', 42, False)
     app.add_directive('clsdir', ClassDirective)
     app.add_object_type('userdesc', 'userdescrole', '%s (userdesc)',
                         userdesc_parse, objname='user desc')

tests/roots/test-root/ext.py

@@ -1,5 +0,0 @@
-# Test extension module
-
-
-def setup(app):
-    app.add_config_value('value_from_ext', [], False)

tests/test_application.py

@@ -11,7 +11,7 @@
 import pytest
 from docutils import nodes
 
-from sphinx.application import ExtensionError
+from sphinx.errors import ExtensionError
 from sphinx.domains import Domain
 from sphinx.testing.util import strip_escseq
 from sphinx.util import logging

tests/test_config.py

@@ -74,20 +74,24 @@ def test_core_config(app, status, warning):
     assert cfg['project'] == cfg.project == 'Sphinx Tests'
 
 
-def test_extension_values(app, status, warning):
-    cfg = app.config
+def test_extension_values():
+    config = Config()
 
-    # default value
-    assert cfg.value_from_ext == []
-    # non-default value
-    assert cfg.value_from_conf_py == 84
+    # check standard settings
+    assert config.master_doc == 'contents'
 
-    # no duplicate values allowed
+    # can't override it by add_config_value()
     with pytest.raises(ExtensionError) as excinfo:
-        app.add_config_value('html_title', 'x', True)
+        config.add('master_doc', 'index', 'env', None)
     assert 'already present' in str(excinfo.value)
+
+    # add a new config value
+    config.add('value_from_ext', [], 'env', None)
+    assert config.value_from_ext == []
+
+    # can't override it by add_config_value()
     with pytest.raises(ExtensionError) as excinfo:
-        app.add_config_value('value_from_ext', 'x', True)
+        config.add('value_from_ext', [], 'env', None)
     assert 'already present' in str(excinfo.value)