assert_matches2

A replacement for the assert_matches crate, providing an assert_matches! macro without support for if guards and the extra arm, but bringing any names introduced in the pattern into scope for after the macro invocation, by expanding to let else.

Example

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");