ratatui/tests/terminal.rs

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

#[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 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(())
}