rust-analyzer/crates/libeditor/src/test_utils.rs

use libsyntax2::{File, TextUnit};
pub use _test_utils::*;
use LocalEdit;

pub fn check_action<F: Fn(&File, TextUnit) -> Option<LocalEdit>> (
    before: &str,
    after: &str,
    f: F,
) {
    let (before_cursor_pos, before) = extract_offset(before);
    let file = File::parse(&before);
    let result = f(&file, before_cursor_pos).expect("code action is not applicable");
    let actual = result.edit.apply(&before);
    let actual_cursor_pos = match result.cursor_position {
        None => result.edit.apply_to_offset(before_cursor_pos).unwrap(),
        Some(off) => off,
    };
    let actual = add_cursor(&actual, actual_cursor_pos);
    assert_eq_text!(after, &actual);
}