You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: tests.rs
    path of file: ./repos/joystream/runtime-modules/forum/src
    
    the code of the file until where you have to start completion: #![cfg(test)]

use super::*;
use crate::mock::*;
use frame_support::traits::Currency;
use sp_std::iter::FromIterator;

/// test cases are arranged as two layers.
/// first layer is each method in defined in module.
/// second layer is each pa
    
fn delete_category() {
    let forum_lead = FORUM_LEAD_ORIGIN_ID;
    let origin = OriginType::Signed(forum_lead);
    with_test_externalities(|| {
        let category_id = create_category_mock(
            origin.clone(),
            None,
            good_category_title(),
            good_category_description(),
            Ok(()),
        );
        assert!(<CategoryById<Runtime>>::contains_key(category_id));
        delete_category_mock(origin.clone(), PrivilegedActor::Lead, category_id, Ok(()));
        assert!(!<CategoryById<Runtime>>::contains_key(category_id));
    });
}