Test
，Rust ，， Test-Driven 。，、，Test-Driven 。Tests，Tests、Tests，。
Compréhension
```rust
pub fn greeting(name: &str) -> String {
String::from("Hello!")
}
pub struct Guess {
value: i32,
}
impl Guess {
pub fn new(value: i32) -> Guess {
if value < 1 || value > 100 {
panic!("Guess value must be between 1 and 100, got {}.", value);
}
Guess { value }
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn it_works() {
// 也有 assert_ne! 可以使用
assert_eq!(2 + 2, 4);
}
#[test]
fn will_fail() {
panic!("Make this test fail");
}
#[test]
fn greeting_contains_name() {
let result = greeting("Carol");
// assert 时如果不符合预期，可以 print hint
assert!(
result.contains("Carol"),
"Greeting did not contain name, value was `{}`",
result
);
}
#[test]
#[should_panic]
// should_panic 用于检测是否 panic
fn greater_than_100() {
Guess::new(200);
}
}
#[cfg(test)]
mod tests2 {
#[test]
// 使用 Result<T, E> 作为retour值，无法使用 should_panic trait
fn it_works() -> Result<(), String> {
if 2 + 2 == 4 {
Ok(())
} else {
Err(String::from("two plus two does not equal four"))
}
}
}
```