Function near 

pub fn near<T: Debug + Float + Copy>(
    expected: T,
    max_abs_error: T,
) -> NearMatcher<T>

Matches a value equal within max_abs_error of expected.

The type T of the actual, expected, and max_abs_error values must implement Float.

The values expected and max_abs_error may not be NaN. The value max_abs_error must be non-negative. The matcher panics on construction otherwise.

verify_that!(1.0, near(1.0, 0.1))?; // Passes
verify_that!(1.01, near(1.0, 0.1))?; // Passes
verify_that!(1.25, near(1.0, 0.25))?; // Passes
verify_that!(0.75, near(1.0, 0.25))?; // Passes
verify_that!(1.101, near(1.0, 0.1))?; // Fails
verify_that!(0.899, near(1.0, 0.1))?; // Fails
verify_that!(100.25, near(100.0, 0.25))?; // Passes

The default behaviour for special values is consistent with the IEEE floating point standard. Thus infinity is infinitely far away from any floating point value:

verify_that!(f64::INFINITY, near(0.0, f64::MAX))?; // Fails
verify_that!(0.0, near(f64::INFINITY, f64::MAX))?; // Fails
verify_that!(f64::INFINITY, near(f64::INFINITY, f64::MAX))?; // Fails

Similarly, by default, NaN is infinitely far away from any value:

verify_that!(f64::NAN, near(0.0, f64::MAX))?; // Fails
verify_that!(0.0, near(f64::NAN, f64::MAX))?; // Fails
verify_that!(f64::NAN, near(f64::NAN, f64::MAX))?; // Fails

To treat two NaN values as equal, use the method NearMatcher::nans_are_equal.

verify_that!(f64::NAN, near(f64::NAN, f64::MAX).nans_are_equal())?; // Passes