assert_matches2

assert_matches crate 的替代品，提供了一个 assert_matches! 宏，没有对 if 守卫和额外分支的支持，但在宏调用之后通过展开到 let else 将任何在模式中引入的名称引入作用域。

示例

use assert_matches2::assert_matches;

/// Basic usage
let var = serde_json::Value::from("a string");
assert_matches!(var, serde_json::Value::String(s));
assert_eq!(s, "a string");

// More complex usages
#[derive(Debug)]
struct Foo {
    bar: Bar,
}

#[derive(Debug)]
enum Bar {
    V1(u8),
    V2 { field: String },
}

let var = Foo { bar: Bar::V1(10) };
assert_matches!(var, Foo { bar: ref r @ Bar::V1(int) });
assert_matches!(r, Bar::V1(_));
assert_eq!(int, 10);

let var = Foo { bar: Bar::V2 { field: "test".to_owned() } };
assert_matches!(var, Foo { bar: Bar::V2 { field: rename } });
assert_eq!(rename, "test");