Macro assert_approx_eq_abs 

macro_rules! assert_approx_eq_abs {
    ($lhs:expr, $rhs:expr $(,)?) => { ... };
    ($lhs:expr, $rhs:expr, message = $($arg:tt)+) => { ... };
    ($lhs:expr, $rhs:expr, $tol:expr, message = $($arg:tt)+) => { ... };
    ($lhs:expr, $rhs:expr, $tol:expr $(,)?) => { ... };
}

Asserts that two values are approximately equal using ApproxEqAbs. Pass a third argument to override the default absolute tolerance, or message = ... to provide a custom assertion message while using the default tolerance.