assert-rs 0.1.0

#![cfg_attr(doc, doc = include_str!("../README.md"))]
#![cfg_attr(not(feature = "std"), no_std)]

pub mod assertion;
pub use assertion::Assertion;

use assertion::{BinaryAssertion, UnaryAssertion};

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

/// A wrapper around some object that can be reasoned about.
///
/// Use [`assert_that!`] to construct an `Assert` and then use methods to make some [`Assertion`].
/// `Assertion`s can be returned from tests and verified by the test framework.
#[derive(Debug, Clone, Copy)]
#[must_use = "this blank assertion will do nothing unless it is tested"]
pub struct Assert<T> {
    this: T,
    info: AssertInfo,
}

/// Information about an invocation of [`assert_that!`].
#[derive(Debug, Clone, Copy)]
pub struct AssertInfo {
    file: &'static str,
    line: u32,
    column: u32,
}

impl AssertInfo {
    const fn reassert<T>(self, val: T) -> Assert<T> {
        Assert {
            this: val,
            info: self,
        }
    }
}

impl Display for AssertInfo {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        let Self { file, line, column } = *self;
        write!(f, "{file}:{line}:{column}")
    }
}

/// Construct the first part of an [`Assertion`].
///
/// ```no_run
/// #[test]
/// fn is_equal_to() -> impl Assertion {
///     assert_that!(1 + 2).is_equal_to(3)
/// }
/// ```
#[macro_export]
macro_rules! assert_that {
    ($this:expr) => {
        $crate::Assert::manual_constructor(
            $this,
            ::core::file!(),
            ::core::line!(),
            ::core::column!(),
        )
    };
}

impl<T> Assert<T> {
    #[doc(hidden)]
    /// Don't use this constructor. [`assert_that!`] will fill in the `file`, `line` and `column`
    /// fields for you and you should use it instead.
    pub const fn manual_constructor(this: T, file: &'static str, line: u32, column: u32) -> Self {
        Self {
            this,
            info: AssertInfo { file, line, column },
        }
    }

    /// Converts from `&Assert<T>` to `Assert<&T>`.
    pub const fn as_ref(&self) -> Assert<&T> {
        Assert {
            this: &self.this,
            info: self.info,
        }
    }

    /// Converts from `Assert<T>` or `&Assert<T>` to `Assert<&T::Target>` via [`Deref`].
    pub fn as_deref<U>(&self) -> Assert<&U>
    where
        T: Deref<Target = U>,
    {
        Assert {
            this: &self.this,
            info: self.info,
        }
    }

    /// Maps an `Assert<T>` to an `Assert<U>` by applying a function to its contained value.
    pub fn map<F, U>(self, f: F) -> Assert<U>
    where
        F: FnOnce(T) -> U,
    {
        self.info.reassert(f(self.this))
    }

    /// Assert that `self` is equal to `other`.
    pub fn is_equal_to<U>(self, other: U) -> BinaryAssertion<T, U>
    where
        T: PartialEq<U> + Debug,
        U: Debug,
    {
        let test_result = self.this == other;
        BinaryAssertion::new(self.this, other, test_result, "lhs == rhs", self.info)
    }

    /// Assert that `self` is not equal to `other`.
    pub fn is_not_equal_to<U>(self, other: U) -> BinaryAssertion<T, U>
    where
        T: PartialEq<U> + Debug,
        U: Debug,
    {
        let test_result = self.this != other;
        BinaryAssertion::new(self.this, other, test_result, "lhs != rhs", self.info)
    }

    /// Assert that `self` is greater than `other`.
    pub fn is_greater_than<U>(self, other: U) -> BinaryAssertion<T, U>
    where
        T: PartialOrd<U> + Debug,
        U: Debug,
    {
        let test_result = self.this > other;
        BinaryAssertion::new(self.this, other, test_result, "lhs > rhs", self.info)
    }

    /// Assert that `self` is less than `other`.
    pub fn is_less_than<U>(self, other: U) -> BinaryAssertion<T, U>
    where
        T: PartialOrd<U> + Debug,
        U: Debug,
    {
        let test_result = self.this < other;
        BinaryAssertion::new(self.this, other, test_result, "lhs < rhs", self.info)
    }

    /// Assert that `self` is greater than or equal to `other`.
    pub fn is_greater_than_or_equal_to<U>(self, other: U) -> BinaryAssertion<T, U>
    where
        T: PartialOrd<U> + Debug,
        U: Debug,
    {
        let test_result = self.this >= other;
        BinaryAssertion::new(self.this, other, test_result, "lhs >= rhs", self.info)
    }

    /// Assert that `self` is less than or equal to `other`.
    pub fn is_less_than_or_equal_to<U>(self, other: U) -> BinaryAssertion<T, U>
    where
        T: PartialOrd<U> + Debug,
        U: Debug,
    {
        let test_result = self.this <= other;
        BinaryAssertion::new(self.this, other, test_result, "lhs <= rhs", self.info)
    }

    /// Assert that `self` is contained by `other`.
    pub fn is_in(self, container: &[T]) -> BinaryAssertion<&[T], T>
    where
        T: PartialEq,
    {
        self.info.reassert(container).contains(self.this)
    }

    /// Assert that `self` is not contained by `other`.
    pub fn is_not_in(self, container: &[T]) -> BinaryAssertion<&[T], T>
    where
        T: PartialEq,
    {
        self.info.reassert(container).does_not_contain(self.this)
    }
}

impl<T> Assert<&T> {
    /// Maps an `Assert<&T>` to `Assert<T>` by cloning the contained value.
    pub fn cloned(self) -> Assert<T>
    where
        T: Clone,
    {
        Assert {
            this: self.this.clone(),
            info: self.info,
        }
    }

    /// Maps an `Assert<&T>` to `Assert<T>` by copying the contained value.
    pub const fn copied(self) -> Assert<T>
    where
        T: Copy,
    {
        Assert {
            this: *self.this,
            info: self.info,
        }
    }
}

impl Assert<bool> {
    /// Assert that `self` is true.
    pub const fn is_true(self) -> UnaryAssertion<bool> {
        UnaryAssertion::new(self.this, self.this, "this.is_true()", self.info)
    }

    /// Assert that `self` is false.
    pub const fn is_false(self) -> UnaryAssertion<bool> {
        UnaryAssertion::new(self.this, !self.this, "this.is_false()", self.info)
    }
}

impl<T: Debug> Assert<Option<T>> {
    /// Assert that `self` is `Some`.
    pub fn is_some(self) -> UnaryAssertion<Option<T>> {
        let test_result = self.this.is_some();
        UnaryAssertion::new(self.this, test_result, "this.is_some()", self.info)
    }

    /// Assert that `self` is `None`.
    pub fn is_none(self) -> UnaryAssertion<Option<T>> {
        let test_result = self.this.is_none();
        UnaryAssertion::new(self.this, test_result, "this.is_none()", self.info)
    }

    /// Assert that `self` is `Some` and the `Some` value matches a predicate.
    pub fn is_some_and<F, A>(self, f: F) -> UnaryAssertion<Option<T>>
    where
        F: Fn(Assert<&T>) -> A,
        A: Assertion,
    {
        let test_result = self
            .this
            .as_ref()
            .is_some_and(|opt| f(self.info.reassert(opt)).test());
        UnaryAssertion::new(self.this, test_result, "this.is_some_and(f)", self.info)
    }

    /// Assert that `self` is `None` or the `Some` value matches a predicate.
    pub fn is_none_or<F, A>(self, f: F) -> UnaryAssertion<Option<T>>
    where
        F: Fn(Assert<&T>) -> A,
        A: Assertion,
    {
        let test_result = self
            .this
            .as_ref()
            .is_none_or(|opt| f(self.info.reassert(opt)).test());
        UnaryAssertion::new(self.this, test_result, "this.is_none_or(f)", self.info)
    }
}

impl<T: Debug, E: Debug> Assert<Result<T, E>> {
    /// Assert that `self` is `Ok`.
    pub fn is_ok(self) -> UnaryAssertion<Result<T, E>> {
        let test_result = self.this.is_ok();
        UnaryAssertion::new(self.this, test_result, "this.is_ok()", self.info)
    }

    /// Assert that `self` is `Err`.
    pub fn is_err(self) -> UnaryAssertion<Result<T, E>> {
        let test_result = self.this.is_err();
        UnaryAssertion::new(self.this, test_result, "this.is_err()", self.info)
    }

    /// Assert that `self` is `Ok` and the `Ok` value matches a predicate.
    pub fn is_ok_and<F, A>(self, f: F) -> impl Assertion
    where
        F: Fn(Assert<&T>) -> A,
        A: Assertion,
    {
        let test_result = self
            .this
            .as_ref()
            .is_ok_and(|o| f(self.info.reassert(o)).test());
        UnaryAssertion::new(self.this, test_result, "this.is_ok_and(f)", self.info)
    }

    /// Assert that `self` is `Err` and the `Err` value matches a predicate.
    pub fn is_err_and<F, A>(self, f: F) -> UnaryAssertion<Result<T, E>>
    where
        F: Fn(Assert<&E>) -> A,
        A: Assertion,
    {
        let test_result = self
            .this
            .as_ref()
            .is_err_and(|e| f(self.info.reassert(e)).test());
        UnaryAssertion::new(self.this, test_result, "this.is_err_and(f)", self.info)
    }
}

impl<'a, T> Assert<&'a [T]> {
    /// Assert that `self` is sorted according to [`PartialOrd::partial_cmp`].
    pub fn is_sorted(self) -> UnaryAssertion<&'a [T]>
    where
        T: PartialOrd,
    {
        let test_result = self.this.is_sorted();
        UnaryAssertion::new(self.this, test_result, "this.is_sorted()", self.info)
    }

    /// Assert that `self` is not sorted according to [`PartialOrd::partial_cmp`].
    pub fn is_not_sorted(self) -> UnaryAssertion<&'a [T]>
    where
        T: PartialOrd,
    {
        let test_result = !self.this.is_sorted();
        UnaryAssertion::new(self.this, test_result, "!this.is_sorted()", self.info)
    }

    /// Assert that `self` is sorted according to the provided comparison function.
    pub fn is_sorted_by<'b, F>(self, compare: F) -> UnaryAssertion<&'a [T]>
    where
        F: FnMut(&'b T, &'b T) -> bool,
        'a: 'b, // is this required? should I just use 'a and remove 'b?
    {
        let test_result = self.this.is_sorted_by(compare);
        UnaryAssertion::new(self.this, test_result, "this.is_sorted_by()", self.info)
    }

    /// Assert that `self` is not sorted according to the provided comparison function.
    pub fn is_not_sorted_by<'b, F>(self, compare: F) -> UnaryAssertion<&'a [T]>
    where
        F: FnMut(&'b T, &'b T) -> bool,
        'a: 'b, // is this required? should I just use 'a and remove 'b?
    {
        let test_result = !self.this.is_sorted_by(compare);
        UnaryAssertion::new(self.this, test_result, "!this.is_sorted_by()", self.info)
    }

    /// Assert that `self` is sorted according to the provided key extraction function.
    pub fn is_sorted_by_key<'b, F, K>(self, f: F) -> UnaryAssertion<&'a [T]>
    where
        F: FnMut(&'b T) -> K,
        K: PartialOrd,
        'a: 'b,
    {
        let test_result = self.this.is_sorted_by_key(f);
        UnaryAssertion::new(self.this, test_result, "this.is_sorted_by_key()", self.info)
    }

    /// Assert that `self` is not sorted according to the provided key extraction function.
    pub fn is_not_sorted_by_key<'b, F, K>(self, f: F) -> UnaryAssertion<&'a [T]>
    where
        F: FnMut(&'b T) -> K,
        K: PartialOrd,
        'a: 'b,
    {
        let test_result = !self.this.is_sorted_by_key(f);
        UnaryAssertion::new(
            self.this,
            test_result,
            "!this.is_sorted_by_key()",
            self.info,
        )
    }

    /// Assert that `self` is empty.
    pub const fn is_empty(self) -> UnaryAssertion<&'a [T]> {
        let test_result = self.this.is_empty();
        UnaryAssertion::new(self.this, test_result, "this.is_empty()", self.info)
    }

    /// Assert that `self` is not empty.
    pub const fn is_not_empty(self) -> UnaryAssertion<&'a [T]> {
        let test_result = !self.this.is_empty();
        UnaryAssertion::new(self.this, test_result, "!this.is_empty()", self.info)
    }

    /// Assert that `self` has the given length.
    pub const fn is_len(self, len: usize) -> BinaryAssertion<&'a [T], usize> {
        let test_result = self.this.len() == len;
        BinaryAssertion::new(self.this, len, test_result, "lhs.is_len(rhs)", self.info)
    }

    /// Assert that `self` does not have the given length.
    pub const fn is_not_len(self, len: usize) -> BinaryAssertion<&'a [T], usize> {
        let test_result = self.this.len() != len;
        BinaryAssertion::new(self.this, len, test_result, "!lhs.is_len(rhs)", self.info)
    }

    /// Assert that `self` contains `elem`.
    pub fn contains(self, elem: T) -> BinaryAssertion<&'a [T], T>
    where
        T: PartialEq,
    {
        let test_result = self.this.contains(&elem);
        BinaryAssertion::new(self.this, elem, test_result, "lhs.contains(rhs)", self.info)
    }

    /// Assert that `self` does not contain `elem`.
    pub fn does_not_contain(self, elem: T) -> BinaryAssertion<&'a [T], T>
    where
        T: PartialEq,
    {
        let test_result = !self.this.contains(&elem);
        BinaryAssertion::new(
            self.this,
            elem,
            test_result,
            "!lhs.contains(rhs)",
            self.info,
        )
    }
}