termdiff 4.1.1

Write a diff with color codes to a string
Documentation 
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use std::borrow::Cow;

use crate::themes::Theme;
use crossterm::style::Stylize;

/// A simple colorful theme using signs
///
/// ```
/// use termdiff::{diff, SignsColorTheme};
/// let old = "The quick brown fox and\njumps over the sleepy dog";
/// let new = "The quick red fox and\njumps over the lazy dog";
/// let mut buffer: Vec<u8> = Vec::new();
/// let  theme = SignsColorTheme::default();
/// diff(&mut buffer, old, new, &theme).unwrap();
/// let actual: String = String::from_utf8(buffer).expect("Not valid UTF-8");
///
/// assert_eq!(
///     actual,
///     "\u{1b}[38;5;9m--- remove\u{1b}[39m | \u{1b}[38;5;10minsert +++\u{1b}[39m\n\u{1b}[38;5;9m-\u{1b}[39m\u{1b}[38;5;9mThe quick brown fox and\n\u{1b}[39m\u{1b}[38;5;9m-\u{1b}[39m\u{1b}[38;5;9mjumps over the sleepy dog\u{1b}[39m\n\u{1b}[38;5;10m+\u{1b}[39m\u{1b}[38;5;10mThe quick red fox and\n\u{1b}[39m\u{1b}[38;5;10m+\u{1b}[39m\u{1b}[38;5;10mjumps over the lazy dog\u{1b}[39m\n"
/// );
/// ```
#[derive(Default, Clone, Copy, Debug)]
pub struct SignsColorTheme {}

impl Theme for SignsColorTheme {
    fn highlight_insert<'this>(&self, input: &'this str) -> Cow<'this, str> {
        input.underlined().green().to_string().into()
    }

    fn highlight_delete<'this>(&self, input: &'this str) -> Cow<'this, str> {
        input.underlined().red().to_string().into()
    }

    fn equal_content<'this>(&self, input: &'this str) -> Cow<'this, str> {
        input.into()
    }

    fn delete_content<'this>(&self, input: &'this str) -> Cow<'this, str> {
        input.red().to_string().into()
    }

    fn equal_prefix<'this>(&self) -> Cow<'this, str> {
        " ".into()
    }

    fn delete_prefix<'this>(&self) -> Cow<'this, str> {
        "-".red().to_string().into()
    }

    fn insert_line<'this>(&self, input: &'this str) -> Cow<'this, str> {
        input.green().to_string().into()
    }

    fn insert_prefix<'this>(&self) -> Cow<'this, str> {
        "+".green().to_string().into()
    }

    fn line_end<'this>(&self) -> Cow<'this, str> {
        "\n".into()
    }

    fn header<'this>(&self) -> Cow<'this, str> {
        format!("{} | {}\n", "--- remove".red(), "insert +++".green()).into()
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::borrow::Cow;

    /// Test that `SignsColorTheme` returns the expected prefixes
    #[test]
    fn test_signs_color_theme_prefixes() {
        let theme = SignsColorTheme::default();
        assert_eq!(theme.equal_prefix(), Cow::Borrowed(" "));
        // Can't directly compare colored strings, so check they contain the expected characters
        assert!(theme.delete_prefix().contains('-'));
        assert!(theme.insert_prefix().contains('+'));
    }

    /// Test that `SignsColorTheme` applies highlighting to content
    #[test]
    fn test_signs_color_theme_highlighting() {
        let theme = SignsColorTheme::default();
        let input = "test";
        // Highlighting should modify the input
        assert_ne!(theme.highlight_insert(input), Cow::Borrowed(input));
        assert_ne!(theme.highlight_delete(input), Cow::Borrowed(input));
        assert_ne!(theme.delete_content(input), Cow::Borrowed(input));
        assert_ne!(theme.insert_line(input), Cow::Borrowed(input));
    }
}