Class modify_settings

django/test/utils.py:568–615

Like override_settings, but makes it possible to append, prepend, or remove items instead of redefining the entire list.

class modify_settings(override_settings):
    """
    Like override_settings, but makes it possible to append, prepend, or remove
    items instead of redefining the entire list.
    """

    def __init__(self, *args, **kwargs):
        if args:
            # Hack used when instantiating from SimpleTestCase.setUpClass.
            assert not kwargs
            self.operations = args[0]
        else:
            assert not args
            self.operations = list(kwargs.items())
        super(override_settings, self).__init__()

    def save_options(self, test_func):
        if test_func._modified_settings is None:
            test_func._modified_settings = self.operations
        else:
            # Duplicate list to prevent subclasses from altering their parent.
            test_func._modified_settings = (
                list(test_func._modified_settings) + self.operations
            )

    def enable(self):
        self.options = {}
        for name, operations in self.operations:
            try:
                # When called from SimpleTestCase.setUpClass, values may be
                # overridden several times; cumulate changes.
                value = self.options[name]
            except KeyError:
                value = list(getattr(settings, name, []))
            for action, items in operations.items():
                # items may be a single value or an iterable.
                if isinstance(items, str):
                    items = [items]
                if action == "append":
                    value += [item for item in items if item not in value]
                elif action == "prepend":
                    value = [item for item in items if item not in value] + value
                elif action == "remove":
                    value = [item for item in value if item not in items]
                else:
                    raise ValueError("Unsupported action: %s" % action)
            self.options[name] = value
        super().enable()


class override_system_checks(TestContextDecorator):