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/rust-analyzer/crates/ide-diagnostics/src
    
    the code of the file until where you have to start completion: #![allow(clippy::print_stderr)]

use ide_db::{
    assists::AssistResolveStrategy, base_db::SourceDatabaseExt, LineIndexDatabase, RootDatabase,
};
use itertools::Itertools;
use stdx::trim_indent;
use test_fixture::WithFixture;
use test_utils::{assert_eq_text, extract_annotations, MiniCore};

use crate::{DiagnosticsConfig, ExprFillDefaultMode, Severity};

/// Takes a multi-file input fixture with annotated cursor positions,
/// and checks that:
///  * a diagnostic is produced
///  * the first diagnostic fix trigger range touches the input cursor position
///  * that the contents of the file containing the cursor match `after` after the diagnostic fix is applied
#[track_caller]
pub(crate) fn check_fix(ra_fixture_before: &str, ra_fixture_after: &str) {
    check_nth_fix(0, ra_fixture_before, ra_fixture_after);
}
/// Takes a multi-file input fixture with annotated cursor positions,
/// and checks that:
///  * a diagnostic is produced
///  * every diagnostic fixes trigger range touches the input cursor position
///  * that the contents of the file containing the cursor match `after` after each diagnostic fix is applied
pub(crate) fn check_fixes(ra_fixture_before: &str, ra_fixtures_after: Vec<&str>) {
    for (i, ra_fixture_after) in ra_fixtures_after.ite
    
pub(crate) fn check_has_single_fix(ra_fixture_before: &str, ra_fixture_after: &str) {
    let after = trim_indent(ra_fixture_after);

    let (db, file_position) = RootDatabase::with_position(ra_fixture_before);
    let mut conf = DiagnosticsConfig::test_sample();
    conf.expr_fill_default = ExprFillDefaultMode::Default;
    let mut n_fixes = 0;
    let fix = super::diagnostics(&db, &conf, &AssistResolveStrategy::All, file_position.file_id)
        .into_iter()
        .find(|d| {
            d.fixes
                .as_ref()
                .and_then(|fixes| {
                    n_fixes += fixes.len();
                    fixes.iter().find(|fix| {
                        if !fix.target.contains_inclusive(file_position.offset) {
                            return false;
                        }
                        let actual = {
                            let source_change = fix.source_change.as_ref().unwrap();
                            let file_id = *source_change.source_file_edits.keys().next().unwrap();
                            let mut actual = db.file_text(file_id).to_string();

                            for (edit, snippet_edit) in source_change.source_file_edits.values() {
                                edit.apply(&mut actual);
                                if let Some(snippet_edit) = snippet_edit {
                                    snippet_edit.apply(&mut actual);
                                }
                            }
                            actual
                        };
                        after == actual
                    })
                })
                .is_some()
        });
    assert!(fix.is_some(), "no diagnostic with desired fix");
    assert!(n_fixes == 1, "Too many fixes suggested");
}