lets_expect_assertions 0.5.2

lets_expect assertions. This crate is internal to the lets_expect crate and should not be used directly.
Documentation 
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use colored::Colorize;

use lets_expect_core::assertions::{
    assertion_error::AssertionError, assertion_result::AssertionResult,
};
use std::{fmt::Debug, ops::Sub};

pub fn from<R>(expected: R) -> impl Fn(&R, &R) -> AssertionResult
where
    R: Debug + PartialEq,
{
    move |from, _| {
        if expected == *from {
            Ok(())
        } else {
            let expected = format!("{:?}", expected).green().bold();
            let from = format!("{:?}", from).red().bold();
            Err(AssertionError {
                message: vec![format!(
                    "Expected to change from {}, but it was {} instead",
                    expected, from
                )],
            })
        }
    }
}

pub fn to<R>(expected: R) -> impl Fn(&R, &R) -> AssertionResult
where
    R: Debug + PartialEq,
{
    move |_, to| {
        if expected == *to {
            Ok(())
        } else {
            let expected = format!("{:?}", expected).green().bold();
            let to = format!("{:?}", to).red().bold();
            Err(AssertionError {
                message: vec![format!(
                    "Expected to change to {}, but it was {} instead",
                    expected, to
                )],
            })
        }
    }
}

pub fn by<R>(expected: R) -> impl Fn(&R, &R) -> AssertionResult
where
    R: Debug + PartialEq + Sub<Output = R> + Clone,
{
    move |from, to| {
        let diff = to.clone() - from.clone();
        if expected == diff {
            Ok(())
        } else {
            let expected = format!("{:?}", expected).green().bold();
            let diff = format!("{:?}", diff).red().bold();
            Err(AssertionError {
                message: vec![format!(
                    "Expected to change by {}, but it was changed by {} instead",
                    expected, diff
                )],
            })
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::expected_err::expected_err;
    use colored::control::set_override;

    #[test]
    fn test_from_ok() {
        assert_eq!(from(1)(&1, &2), Ok(()));
    }

    #[test]
    fn test_from_err() {
        set_override(false);
        assert_eq!(
            from(1)(&2, &2),
            expected_err(vec!["Expected to change from 1, but it was 2 instead"])
        );
    }

    #[test]
    fn test_to_ok() {
        assert_eq!(to(2)(&1, &2), Ok(()));
    }

    #[test]
    fn test_to_err() {
        set_override(false);
        assert_eq!(
            to(2)(&1, &1),
            expected_err(vec!["Expected to change to 2, but it was 1 instead"])
        );
    }

    #[test]
    fn test_by_ok() {
        assert_eq!(by(1)(&1, &2), Ok(()));
    }

    #[test]
    fn test_by_err() {
        set_override(false);
        assert_eq!(
            by(1)(&1, &1),
            expected_err(vec![
                "Expected to change by 1, but it was changed by 0 instead"
            ])
        );
    }
}