Trait faux::ArgMatcher

source · [−]
pub trait ArgMatcher<Arg: ?Sized>: Display {
    fn matches(&self, argument: &Arg) -> bool;

    fn into_ref_matcher(self) -> RefMatcher<Self>
    where
        Self: Sized,
    { ... }
}
Expand description

Matcher for single argument of a method.

Implementors provide an expectation to match an argument against.

faux provides some simple matchers: any(), eq(), and eq_against(). Additionally, faux also provides two macros: pattern! for pattern matching and from_fn! to provide a custom function.

You may define your own matcher for special use cases. The fmt::Display implementation is used by InvocationMatcher to display the expectation when any arguments failed to match.

Examples

use std::fmt::{self, Formatter};
use faux::ArgMatcher;

struct HasLength(usize);

// displayed as the expectation when any argument fails to match
// when used by an `InvocationMatcher`
impl fmt::Display for HasLength {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        write!(f, "_.len() == {}", self.0)
    }
}

impl <T> ArgMatcher<&[T]> for HasLength {
    // matches takes a reference to the argument
    // the argument is &[T] so it takes &&[T]
    fn matches(&self, argument: &&[T]) -> bool {
        argument.len() == self.0
    }
}

let has_three_length = HasLength(3);
let vec = vec![56, 78, 12, 43, 23];
assert!(has_three_length.matches(&&vec[..3]));
assert!(!has_three_length.matches(&&vec[1..]));

Required Methods

Checks if the argument matches the determined expectation.

use faux::matcher::{self, ArgMatcher};

let eq_five = matcher::eq(5);
assert!(eq_five.matches(&5));
assert!(!eq_five.matches(&4));

Provided Methods

Converts the Argmatcher<Arg> into an ArgMatcher<&Arg> to test against the reference of the argument.

Implementors