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

use ra_syntax::{SourceFile, TextUnit};

use crate::LocalEdit;
pub use test_utils::*;

pub fn check_action<F: Fn(&SourceFile, TextUnit) -> Option<LocalEdit>>(
    before: &str,
    after: &str,
    f: F,
) {
    let (before_cursor_pos, before) = extract_offset(before);
    let file = SourceFile::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)
            .expect("cursor position is affected by the edit"),
        Some(off) => off,
    };
    let actual = add_cursor(&actual, actual_cursor_pos);
    assert_eq_text!(after, &actual);
}