Macro assert_matches::assert_matches
source · macro_rules! assert_matches { ( $e:expr , $($pat:pat)|+ ) => { ... }; ( $e:expr , $($pat:pat)|+ if $cond:expr ) => { ... }; ( $e:expr , $($pat:pat)|+ => $arm:expr ) => { ... }; ( $e:expr , $($pat:pat)|+ if $cond:expr => $arm:expr ) => { ... }; ( $e:expr , $($pat:pat)|+ , $($arg:tt)* ) => { ... }; ( $e:expr , $($pat:pat)|+ if $cond:expr , $($arg:tt)* ) => { ... }; ( $e:expr , $($pat:pat)|+ => $arm:expr , $($arg:tt)* ) => { ... }; ( $e:expr , $($pat:pat)|+ if $cond:expr => $arm:expr , $($arg:tt)* ) => { ... }; }
Expand description
Asserts that an expression matches a given pattern.
A guard expression may be supplied to add further restrictions to the expected value of the expression.
A match
arm may be supplied to perform additional assertions or to yield
a value from the macro invocation.
§Examples
#[macro_use] extern crate assert_matches;
#[derive(Debug)]
enum Foo {
A(i32),
B(&'static str),
}
let a = Foo::A(1);
// Assert that `a` matches the pattern `Foo::A(_)`.
assert_matches!(a, Foo::A(_));
// Assert that `a` matches the pattern and
// that the contained value meets the condition `i > 0`.
assert_matches!(a, Foo::A(i) if i > 0);
let b = Foo::B("foobar");
// Assert that `b` matches the pattern `Foo::B(_)`.
assert_matches!(b, Foo::B(s) => {
// Perform additional assertions on the variable binding `s`.
assert!(s.starts_with("foo"));
assert!(s.ends_with("bar"));
});
// Assert that `b` matches the pattern and yield the string `s`.
let s = assert_matches!(b, Foo::B(s) => s);
// Perform an assertion on the value `s`.
assert_eq!(s, "foobar");