malevich 1.18.2

Terminal plotting: a small grammar of marks, honest axes, millions of points
Documentation 
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use super::{display_width, display_width_ansi, fit_width_with};

#[test]
fn wide_glyphs_measure_two_columns() {
    assert_eq!(display_width("abc"), 3);
    assert_eq!(display_width("\u{65E5}\u{672C}"), 4);
    assert_eq!(display_width("a\u{65E5}b"), 4);
}

#[test]
fn ansi_control_strings_are_zero_width() {
    assert_eq!(display_width_ansi("\x1b[31mred\x1b[0m"), 3);
    assert_eq!(
        display_width_ansi("\x1b]8;;https://example.com\x1b\\日本\x1b]8;;\x1b\\"),
        4
    );
    assert_eq!(display_width_ansi("a\x1b_Gpayload\x1b\\b"), 2);
    assert_eq!(display_width_ansi("\x1b[31"), 0);
}

#[test]
fn every_control_string_prefix_is_safe_to_measure() {
    let text = "\x1b[38;2;1;2;3mred\x1b[0m \x1b]8;;https://example.com\x1b\\日本\x1b]8;;\x1b\\";
    for end in text
        .char_indices()
        .map(|(index, _)| index)
        .chain(std::iter::once(text.len()))
    {
        let prefix = &text[..end];
        assert!(display_width_ansi(prefix) <= display_width(prefix));
    }
}

#[test]
fn combining_marks_measure_nothing() {
    assert_eq!(display_width("e\u{0301}"), 1);
}

#[test]
fn fitting_keeps_short_text_untouched() {
    assert_eq!(fit_width_with("hi", 4, '\u{2026}'), "hi");
    assert_eq!(fit_width_with("", 0, '\u{2026}'), "");
}

#[test]
fn fitting_truncates_with_an_ellipsis() {
    assert_eq!(fit_width_with("hello", 4, '\u{2026}'), "hel\u{2026}");
    assert_eq!(fit_width_with("hello", 1, '\u{2026}'), "\u{2026}");
}

#[test]
fn fitting_never_splits_a_wide_glyph() {
    // Four columns: the second ideograph (2 columns) cannot fit next to the
    // ellipsis, so it is dropped whole.
    assert_eq!(
        fit_width_with("\u{65E5}\u{672C}\u{8A9E}", 4, '\u{2026}'),
        "\u{65E5}\u{2026}"
    );
}