int-enum 1.2.0

A derive macro for conversion between integer and enum types.
Documentation 
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use int_enum::IntEnum;

#[test]
fn basic() {
    #[derive(Debug, PartialEq, IntEnum)]
    #[repr(u8)]
    enum Basic {
        Zero = 0,
        One = 1,
        Two = 2,
    }

    assert_eq!(u8::from(Basic::Zero), 0);
    assert_eq!(u8::from(Basic::One), 1);
    assert_eq!(u8::from(Basic::Two), 2);

    assert_eq!(Basic::try_from(0), Ok(Basic::Zero));
    assert_eq!(Basic::try_from(1), Ok(Basic::One));
    assert_eq!(Basic::try_from(2), Ok(Basic::Two));
    assert_eq!(Basic::try_from(3), Err(3));
}

#[test]
fn signed() {
    #[derive(Debug, PartialEq, IntEnum)]
    #[repr(i8)]
    enum Signed {
        MinusOne = -1,
        One = 1,
    }

    assert_eq!(i8::from(Signed::MinusOne), -1);
    assert_eq!(i8::from(Signed::One), 1);

    assert_eq!(Signed::try_from(-1), Ok(Signed::MinusOne));
    assert_eq!(Signed::try_from(1), Ok(Signed::One));
    assert_eq!(Signed::try_from(0), Err(0));
}

#[test]
fn repr_with_align() {
    #[derive(Debug, PartialEq, IntEnum)]
    #[repr(u16, align(4))]
    enum WithAlign {
        A = 0x41,
        B = 0x42,
    }

    assert_eq!(u16::from(WithAlign::A), 0x41);
    assert_eq!(u16::from(WithAlign::B), 0x42);

    assert_eq!(WithAlign::try_from(0x41), Ok(WithAlign::A));
    assert_eq!(WithAlign::try_from(0x42), Ok(WithAlign::B));
    assert_eq!(WithAlign::try_from(0x43), Err(0x43));
}

#[test]
fn discriminant_expr() {
    #[derive(Debug, PartialEq, IntEnum)]
    #[repr(u16)]
    enum Expr {
        Up = 1 << 0,
        Down = 1 << 1,
        Left = 1 << 2,
        Right = 1 << 3,
    }

    assert_eq!(u16::from(Expr::Up), 1 << 0);
    assert_eq!(u16::from(Expr::Down), 1 << 1);
    assert_eq!(u16::from(Expr::Left), 1 << 2);
    assert_eq!(u16::from(Expr::Right), 1 << 3);

    assert_eq!(Expr::try_from(1 << 0), Ok(Expr::Up));
    assert_eq!(Expr::try_from(1 << 1), Ok(Expr::Down));
    assert_eq!(Expr::try_from(1 << 2), Ok(Expr::Left));
    assert_eq!(Expr::try_from(1 << 3), Ok(Expr::Right));
    assert_eq!(Expr::try_from(1 << 4), Err(1 << 4));
}

#[test]
fn missing_discriminants() {
    // Ensuring conformity with the documented behavior of implicit discriminators.
    // https://doc.rust-lang.org/reference/items/enumerations.html#r-items.enum.discriminant.implicit
    #[derive(Debug, PartialEq, IntEnum)]
    #[repr(i16)]
    enum NoDiscr {
        Zero,
        MinusOne = -1,
        One = 1,
        Two,
        MinusFive = -5,
        MinusFour,
        MinusThree,
    }

    assert_eq!(i16::from(NoDiscr::Zero), 0);
    assert_eq!(i16::from(NoDiscr::MinusOne), -1);
    assert_eq!(i16::from(NoDiscr::One), 1);
    assert_eq!(i16::from(NoDiscr::Two), 2);
    assert_eq!(i16::from(NoDiscr::MinusFive), -5);
    assert_eq!(i16::from(NoDiscr::MinusFour), -4);

    assert_eq!(NoDiscr::try_from(0), Ok(NoDiscr::Zero));
    assert_eq!(NoDiscr::try_from(-1), Ok(NoDiscr::MinusOne));
    assert_eq!(NoDiscr::try_from(1), Ok(NoDiscr::One));
    assert_eq!(NoDiscr::try_from(2), Ok(NoDiscr::Two));
    assert_eq!(NoDiscr::try_from(-5), Ok(NoDiscr::MinusFive));
    assert_eq!(NoDiscr::try_from(-4), Ok(NoDiscr::MinusFour));
    assert_eq!(NoDiscr::try_from(-3), Ok(NoDiscr::MinusThree));
    assert_eq!(NoDiscr::try_from(-2), Err(-2));
    assert_eq!(NoDiscr::try_from(3), Err(3));
}

#[test]
fn default_repr_isize() {
    #[derive(Debug, PartialEq, IntEnum)]
    enum NoRepr {
        A = 1,
    }

    assert_eq!(isize::from(NoRepr::A), 1);

    assert_eq!(NoRepr::try_from(1isize), Ok(NoRepr::A));
}

// Test case for issue #17.
// https://github.com/Juici/int-enum-rs/issues/17
#[test]
fn allow_error_variant_name_issue17() {
    #[derive(IntEnum)]
    enum Issue17 {
        Error = 0,
    }
}