ratatui/tests/terminal.rs

use ratatui::{
    backend::{Backend, TestBackend},
    layout::Rect,
    widgets::Paragraph,
    Terminal,
};
use std::error::Error;

#[test]
fn terminal_buffer_size_should_be_limited() {
    let backend = TestBackend::new(400, 400);
    let terminal = Terminal::new(backend).unwrap();
    let size = terminal.backend().size().unwrap();
    assert_eq!(size.width, 255);
    assert_eq!(size.height, 255);
}

#[test]
fn swap_buffer_clears_prev_buffer() {
    let backend = TestBackend::new(100, 50);
    let mut terminal = Terminal::new(backend).unwrap();
    terminal
        .current_buffer_mut()
        .set_string(0, 0, "Hello", ratatui::style::Style::reset());
    assert_eq!(terminal.current_buffer_mut().content()[0].symbol, "H");
    terminal.swap_buffers();
    assert_eq!(terminal.current_buffer_mut().content()[0].symbol, " ");
}

#[test]
fn terminal_draw_returns_the_completed_frame() -> Result<(), Box<dyn Error>> {
    let backend = TestBackend::new(10, 10);
    let mut terminal = Terminal::new(backend)?;
    let frame = terminal.draw(|f| {
        let paragraph = Paragraph::new("Test");
        f.render_widget(paragraph, f.size());
    })?;
    assert_eq!(frame.buffer.get(0, 0).symbol, "T");
    assert_eq!(frame.area, Rect::new(0, 0, 10, 10));
    terminal.backend_mut().resize(8, 8);
    let frame = terminal.draw(|f| {
        let paragraph = Paragraph::new("test");
        f.render_widget(paragraph, f.size());
    })?;
    assert_eq!(frame.buffer.get(0, 0).symbol, "t");
    assert_eq!(frame.area, Rect::new(0, 0, 8, 8));
    Ok(())
}