终端程序的集成测试，就像测试网页一样 app. termlens 在真实的伪终端中生成你的真实二进制，渲染 其通过VT仿真器输出到内存中的屏幕网格，并且允许 测试、等待、断言并快照网格——用户会做的 看，不是生成它的字节。

Ratatui的快照测试配方 包含一个术语lens示例，用于通过PTY测试编译后的应用程序。 与TestBackend快照一起使用，以覆盖交互和处理过程 行为。

为什么

过程中的控件测试会把你的draw函数渲染成缓冲区。它确实如此 快速且精准，且无法看到draw与用户之间的任何东西 眼睛。项透镜是第二层，适用于少量端到端流动 通过真实二元对立：

• 终端状态 — 原始模式，切换到替代屏幕，进入和离开， 光标在q或恐慌后恢复，应用程序切换的模式 以及是否关闭了它们。
• 实际绘制的内容 — 方框绘画、色彩、宽字符、a 密码字段被隐藏，而不是以透明打印，是个乱七八糟的

termlens

Integration testing for terminal programs, the way you would test a web app. termlens spawns your real binary in a real pseudo-terminal, renders its output through a VT emulator into an in-memory screen grid, and lets a test wait on, assert against and snapshot that grid — what a user would see, not the bytes that produced it.

Ratatui’s snapshot-testing recipe includes a termlens example for testing a compiled application through a PTY. Use it alongside TestBackend snapshots to cover interactions and process behaviour.

Why

An in-process widget test renders your draw function into a buffer. It is fast and precise, and it cannot see anything between draw and the user’s eyes. termlens is the second layer, for a small number of end-to-end flows through the real binary:

• Terminal state — raw mode and the alternate screen entered and left, the cursor restored after q or a panic, the modes the application turned on and whether it turned them off.
• What is actually drawn — box drawing, colours, wide characters, a password field that is concealed rather than printed in clear, a stray println! or panic message that never went through the framework.
• Real input and real signals — keys, mouse and paste encoded exactly as the terminal encodes them under the modes the application enabled; a SIGWINCH that the application must survive.
• Behaviour that changes no cell — a repaint that drew nothing, a bell on a rejected key, an image that went out as pixels when it should have been text.

Every wait is deadline-bounded, and every failure carries the screen: a CI log shows what the application was displaying, not assertion failed: false.

Quick start

cargo add termlens --dev
cargo add insta --dev    # used by the snapshot assertions below

use std::time::Duration;
use termlens::{Key, Terminal};

#[test]
fn quits_from_the_main_screen() -> termlens::Result {
    let mut t = Terminal::builder()
        .size(80, 24)
        .env_clear()                       // hermetic: no host env leaks in
        .timeout(Duration::from_secs(5))   // every wait_* has this deadline
        .spawn(env!("CARGO_BIN_EXE_myapp"))?;

    // Wait for the app's ready marker, let the picture settle, then snapshot
    // it with its styles — the three decisions every TUI snapshot needs.
    termlens::assert_screen_snapshot!(t, after = |s| s.contains("Ready"));