assert-rs 0.1.0

use core::fmt::{Debug, Display};

use crate::AssertInfo;

#[cfg(feature = "std")]
#[must_use = "assertions do not fire unless returned from a test"]
/// An assertion that has been made about some object.
pub trait Assertion: Debug + Display + std::process::Termination {
    /// `true` if the assertion was true.
    fn test(&self) -> bool;

    /// Wrap the assertion in [`ShouldFail`], inverting its condition.
    fn should_fail(self) -> ShouldFail<Self>
    where
        Self: Sized,
    {
        ShouldFail(self)
    }

    /// Panic if the assertion was false.
    ///
    /// # Panics
    ///
    /// See above.
    #[allow(
        clippy::panic,
        reason = "I agree with you clippy, but some people don't care about panics."
    )]
    fn unwrap(&self) {
        assert!(self.test(), "failed assertion was unwrapped:\n{self}");
    }
}

#[cfg(not(feature = "std"))]
#[must_use = "assertions do not fire unless returned from a test"]
/// An assertion that has been made about some object.
pub trait Assertion: Debug + Display {
    /// `true` if the assertion was true.
    fn test(&self) -> bool;

    /// Wrap the assertion in [`ShouldFail`], inverting its condition.
    fn should_fail(self) -> ShouldFail<Self>
    where
        Self: Sized,
    {
        ShouldFail(self)
    }

    /// Panic if the assertion was false.
    ///
    /// # Panics
    ///
    /// See above.
    #[allow(
        clippy::panic,
        reason = "I agree with you clippy, but some people don't care about panics."
    )]
    fn unwrap(&self) {
        assert!(self.test(), "failed assertion was unwrapped:\n{self}");
    }
}

/// An assertion about two objects `lhs` and `rhs`.
#[must_use = "assertions do not fire unless returned from a test"]
pub struct BinaryAssertion<T, U> {
    lhs: T,
    rhs: U,
    test_result: bool,
    test_repr: &'static str,
    info: AssertInfo,
}

impl<T, U> Display for BinaryAssertion<T, U>
where
    T: Debug,
    U: Debug,
{
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        let Self {
            lhs,
            rhs,
            test_result: _,
            test_repr,
            info: AssertInfo { file, line, column },
        } = self;

        write!(
            f,
            "assertion starting at {file}:{line}:{column} failed: `{test_repr}`\n lhs: {lhs:?}\n rhs: {rhs:?}"
        )
    }
}

impl<T, U> Debug for BinaryAssertion<T, U>
where
    T: Debug,
    U: Debug,
{
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        Display::fmt(self, f)
    }
}

impl<T, U> BinaryAssertion<T, U> {
    pub(crate) const fn new(
        lhs: T,
        rhs: U,
        test_result: bool,
        test_repr: &'static str,
        info: AssertInfo,
    ) -> Self {
        Self {
            lhs,
            rhs,
            test_result,
            test_repr,
            info,
        }
    }
}

#[cfg(feature = "std")]
impl<T, U> std::process::Termination for BinaryAssertion<T, U>
where
    T: Debug,
    U: Debug,
{
    fn report(self) -> std::process::ExitCode {
        if self.test() {
            std::process::ExitCode::SUCCESS
        } else {
            println!("{self}");
            std::process::ExitCode::FAILURE
        }
    }
}

impl<T, U> Assertion for BinaryAssertion<T, U>
where
    T: Debug,
    U: Debug,
{
    fn test(&self) -> bool {
        self.test_result
    }
}

/// An assertion about an object `this`.
#[must_use = "assertions do not fire unless returned from a test"]
pub struct UnaryAssertion<T> {
    this: T,
    test_result: bool,
    test_repr: &'static str,
    info: AssertInfo,
}

impl<T> Display for UnaryAssertion<T>
where
    T: Debug,
{
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        let Self {
            this,
            test_result: _,
            test_repr,
            info: AssertInfo { file, line, column },
        } = self;

        write!(
            f,
            "assertion starting at {file}:{line}:{column} failed: `{test_repr}`\nthis: {this:?}"
        )
    }
}

impl<T> Debug for UnaryAssertion<T>
where
    T: Debug,
{
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        Display::fmt(self, f)
    }
}

impl<T> UnaryAssertion<T> {
    pub(crate) const fn new(
        this: T,
        test_result: bool,
        test_repr: &'static str,
        info: AssertInfo,
    ) -> Self {
        Self {
            this,
            test_result,
            test_repr,
            info,
        }
    }
}

#[cfg(feature = "std")]
impl<T> std::process::Termination for UnaryAssertion<T>
where
    T: Debug,
{
    fn report(self) -> std::process::ExitCode {
        if self.test() {
            std::process::ExitCode::SUCCESS
        } else {
            println!("{self}");
            std::process::ExitCode::FAILURE
        }
    }
}

impl<T> Assertion for UnaryAssertion<T>
where
    T: Debug,
{
    fn test(&self) -> bool {
        self.test_result
    }
}

/// An assertion that will unconditionally succeed.
#[must_use = "assertions do not fire unless returned from a test"]
pub struct Succeed {
    info: AssertInfo,
}

impl Display for Succeed {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        let AssertInfo { file, line, column } = self.info;

        write!(
            f,
            "assertion starting at {file}:{line}:{column} was forced success"
        )
    }
}

impl Debug for Succeed {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        Display::fmt(self, f)
    }
}

impl Succeed {
    #[doc(hidden)]
    /// Don't use this constructor. Use [`succeed!`] instead.
    pub const fn manual_constructor(file: &'static str, line: u32, column: u32) -> Self {
        Self {
            info: AssertInfo { file, line, column },
        }
    }
}

#[cfg(feature = "std")]
impl std::process::Termination for Succeed {
    fn report(self) -> std::process::ExitCode {
        std::process::ExitCode::SUCCESS
    }
}

impl Assertion for Succeed {
    fn test(&self) -> bool {
        true
    }
}

/// Construct an [`Assertion`] that will always succeed.
///
/// ```no_run
/// #[test]
/// fn succeed() -> impl Assertion {
///     succeed!()
/// }
/// ```
#[macro_export]
macro_rules! succeed {
    () => {
        $crate::assertion::Succeed::manual_constructor(
            ::core::file!(),
            ::core::line!(),
            ::core::column!(),
        )
    };
}

/// An assertion that will unconditionally fail.
#[must_use = "assertions do not fire unless returned from a test"]
pub struct Fail {
    info: AssertInfo,
}

impl Display for Fail {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        let AssertInfo { file, line, column } = self.info;

        write!(
            f,
            "assertion starting at {file}:{line}:{column} was forced fail"
        )
    }
}

impl Debug for Fail {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        Display::fmt(self, f)
    }
}

impl Fail {
    #[doc(hidden)]
    /// Don't use this constructor. Use [`fail!`] instead.
    pub const fn manual_constructor(file: &'static str, line: u32, column: u32) -> Self {
        Self {
            info: AssertInfo { file, line, column },
        }
    }
}

#[cfg(feature = "std")]
impl std::process::Termination for Fail {
    fn report(self) -> std::process::ExitCode {
        std::process::ExitCode::FAILURE
    }
}

impl Assertion for Fail {
    fn test(&self) -> bool {
        false
    }
}

/// Construct an [`Assertion`] that will always fail.
///
/// ```no_run
/// #[test]
/// fn fail() -> impl Assertion {
///     fail!().should_fail()
/// }
/// ```
#[macro_export]
macro_rules! fail {
    () => {
        $crate::assertion::Fail::manual_constructor(
            ::core::file!(),
            ::core::line!(),
            ::core::column!(),
        )
    };
}

/// An assertion that will fail if the given assertion was true
/// and succeed if the given assertion was false.
pub struct ShouldFail<A: Assertion>(A);

impl<A: Assertion> Display for ShouldFail<A> {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        let inner = &self.0;
        write!(f, "assertion expected to fail succeeded:\n{inner}")
    }
}

#[cfg(feature = "std")]
impl<A: Assertion> std::process::Termination for ShouldFail<A> {
    fn report(self) -> std::process::ExitCode {
        if self.0.test() {
            println!("{self}");
            std::process::ExitCode::FAILURE
        } else {
            std::process::ExitCode::SUCCESS
        }
    }
}

impl<A: Assertion> Assertion for ShouldFail<A> {
    fn test(&self) -> bool {
        !self.0.test()
    }
}

impl<A: Assertion> Debug for ShouldFail<A> {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        Display::fmt(self, f)
    }
}

#[cfg(feature = "alloc")]
pub use multi_dyn_assertion::MultiDynAssertion;

#[cfg(feature = "alloc")]
mod multi_dyn_assertion {
    use super::{Assertion, Debug, Display};

    extern crate alloc;
    use alloc::boxed::Box;

    /// A group of assertions, possibly of different types, all tested simultaneously.
    ///
    /// These can be created using the [`multi_assert!`](crate::multi_assert) macro.
    /// See its docs for more.
    pub struct MultiDynAssertion<const N: usize>([Box<dyn Assertion>; N]);

    impl<const N: usize> Display for MultiDynAssertion<N> {
        fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
            write!(f, "assertion failures in a multi-assert:")?;
            for (i, assertion) in self.0.iter().enumerate() {
                if assertion.test() {
                    write!(f, "\n{i}. [ok]")?;
                } else {
                    writeln!(f, "\n{i}. {assertion}")?;
                }
            }
            Ok(())
        }
    }

    impl<const N: usize> MultiDynAssertion<N> {
        #[must_use]
        #[doc(hidden)]
        /// You can use [`multi_assert!`](crate::multi_assert) with `#[dyn]` instead, but it's not required.
        pub fn new(assertions: [Box<dyn Assertion>; N]) -> Self {
            Self(assertions)
        }
    }

    #[cfg(feature = "std")]
    impl<const N: usize> std::process::Termination for MultiDynAssertion<N> {
        fn report(self) -> std::process::ExitCode {
            if self.test() {
                std::process::ExitCode::SUCCESS
            } else {
                println!("{self}");
                std::process::ExitCode::FAILURE
            }
        }
    }

    impl<const N: usize> Assertion for MultiDynAssertion<N> {
        fn test(&self) -> bool {
            self.0.iter().all(|a| a.test())
        }
    }

    impl<const N: usize> Debug for MultiDynAssertion<N> {
        fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
            Display::fmt(self, f)
        }
    }
}

/// A group of assertions, all tested simultaneously.
///
/// These can be created using the [`multi_assert!`](crate::multi_assert) macro.
/// See its docs for more.
pub struct MultiAssertion<A: Assertion, const N: usize>([A; N]);

impl<A: Assertion, const N: usize> Display for MultiAssertion<A, N> {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        write!(f, "assertion failures in a multi-assert:")?;
        for (i, assertion) in self.0.iter().enumerate() {
            if assertion.test() {
                write!(f, "\n{i}. [ok]")?;
            } else {
                writeln!(f, "\n{i}. {assertion}")?;
            }
        }
        Ok(())
    }
}

impl<A: Assertion, const N: usize> MultiAssertion<A, N> {
    #[must_use]
    /// You can use [`multi_assert!`](crate::multi_assert) instead, but it's not required.
    pub const fn new(assertions: [A; N]) -> Self {
        Self(assertions)
    }
}

#[cfg(feature = "std")]
impl<A: Assertion, const N: usize> std::process::Termination for MultiAssertion<A, N> {
    fn report(self) -> std::process::ExitCode {
        if self.test() {
            std::process::ExitCode::SUCCESS
        } else {
            println!("{self}");
            std::process::ExitCode::FAILURE
        }
    }
}

impl<A: Assertion, const N: usize> Assertion for MultiAssertion<A, N> {
    fn test(&self) -> bool {
        self.0.iter().all(Assertion::test)
    }
}

impl<A: Assertion, const N: usize> Debug for MultiAssertion<A, N> {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        Display::fmt(self, f)
    }
}

#[cfg(feature = "alloc")]
#[cfg_attr(doc, doc = include_str!("multi_assert_doc.md"))]
#[macro_export]
macro_rules! multi_assert {
    [#[dyn] $($this:expr),+ $(,)?] => {
        $crate::assertion::MultiDynAssertion::new([
            $(Box::new($this),)+
        ])
    };
    [$($this:expr),+ $(,)?] => {
        $crate::assertion::MultiAssertion::new([
            $($this,)+
        ])
    };
}

#[cfg(not(feature = "alloc"))]
#[cfg_attr(doc, doc = include_str!("multi_assert_doc.md"))]
#[macro_export]
macro_rules! multi_assert {
    [#[dyn] $($this:expr),+ $(,)?] => {
        compile_error!("cannot use #[dyn] if the no_alloc feature is enabled")
    };
    [$($this:expr),+ $(,)?] => {
        $crate::assertion::MultiAssertion::new([
            $($this,)+
        ])
    };
}