src/matchers/conjunction_matcher.rs

// Copyright 2022 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// There are no visible documentation elements in this module.
#![doc(hidden)]

use crate::{
    description::Description,
    matcher::{Matcher, MatcherBase, MatcherResult},
};
use std::fmt::Debug;

/// Matcher created by [`Matcher::and`] and [`all!`].
///
/// Both [`Matcher::and`] and [`all!`] nest on m1. In other words,
/// both `x.and(y).and(z)` and `all![x, y, z]` produce:
/// ```ignore
/// ConjunctionMatcher {
///     m1: ConjunctionMatcher {
///         m1: x,
///         m2: y
///     },
///     m2: z
/// }
/// ```
///
/// This behavior must be respected
/// to ensure that [`Matcher::explain_match`] and [`Matcher::describe`] produce
/// useful descriptions.
///
/// **For internal use only. API stablility is not guaranteed!**
#[doc(hidden)]
#[derive(MatcherBase)]
pub struct ConjunctionMatcher<M1, M2> {
    m1: M1,
    m2: M2,
}

impl<M1, M2> ConjunctionMatcher<M1, M2> {
    pub fn new(m1: M1, m2: M2) -> Self {
        Self { m1, m2 }
    }
}

impl<T: Debug + Copy, M1: Matcher<T>, M2: Matcher<T>> Matcher<T> for ConjunctionMatcher<M1, M2> {
    fn matches(&self, actual: T) -> MatcherResult {
        match (self.m1.matches(actual), self.m2.matches(actual)) {
            (MatcherResult::Match, MatcherResult::Match) => MatcherResult::Match,
            _ => MatcherResult::NoMatch,
        }
    }

    fn explain_match(&self, actual: T) -> Description {
        match (self.m1.matches(actual), self.m2.matches(actual)) {
            (MatcherResult::NoMatch, MatcherResult::Match) => self.m1.explain_match(actual),
            (MatcherResult::Match, MatcherResult::NoMatch) => self.m2.explain_match(actual),
            (_, _) => {
                let m1_description = self.m1.explain_match(actual);
                if m1_description.is_conjunction_description() {
                    m1_description.nested(self.m2.explain_match(actual))
                } else {
                    Description::new()
                        .bullet_list()
                        .collect([m1_description, self.m2.explain_match(actual)])
                        .conjunction_description()
                }
            }
        }
    }

    fn describe(&self, matcher_result: MatcherResult) -> Description {
        let m1_description = self.m1.describe(matcher_result);
        if m1_description.is_conjunction_description() {
            m1_description.push_in_last_nested(self.m2.describe(matcher_result))
        } else {
            let header = if matcher_result.into() {
                "has all the following properties:"
            } else {
                "has at least one of the following properties:"
            };
            Description::new()
                .text(header)
                .nested(
                    Description::new()
                        .bullet_list()
                        .collect([m1_description, self.m2.describe(matcher_result)]),
                )
                .conjunction_description()
        }
    }
}

#[cfg(test)]
mod tests {
    use crate::prelude::*;
    use indoc::indoc;

    #[test]
    fn and_true_true_matches() -> Result<()> {
        verify_that!(1, anything().and(anything()))
    }

    #[test]
    fn and_true_false_does_not_match() -> Result<()> {
        let result = verify_that!(1, anything().and(not(anything())));
        verify_that!(
            result,
            err(displays_as(contains_substring(indoc!(
                "
                Value of: 1
                Expected: has all the following properties:
                  * is anything
                  * never matches
                Actual: 1,
                  which is anything
                "
            ))))
        )
    }

    #[test]
    fn and_false_true_does_not_match() -> Result<()> {
        let result = verify_that!(1, not(anything()).and(anything()));
        verify_that!(
            result,
            err(displays_as(contains_substring(indoc!(
                "
                    Value of: 1
                    Expected: has all the following properties:
                      * never matches
                      * is anything
                    Actual: 1,
                      which is anything
                "
            ))))
        )
    }

    #[test]
    fn and_false_false_does_not_match() -> Result<()> {
        let result = verify_that!(1, not(anything()).and(not(anything())));
        verify_that!(
            result,
            err(displays_as(contains_substring(indoc!(
                "
                Value of: 1
                Expected: has all the following properties:
                  * never matches
                  * never matches
                Actual: 1,
                  * which is anything
                  * which is anything
                "
            ))))
        )
    }

    #[test]
    fn and_long_chain_of_matchers() -> Result<()> {
        let result = verify_that!(
            1,
            anything().and(not(anything())).and(anything()).and(not(anything())).and(anything())
        );
        verify_that!(
            result,
            err(displays_as(contains_substring(indoc!(
                "
                Value of: 1
                Expected: has all the following properties:
                  * is anything
                  * never matches
                  * is anything
                  * never matches
                  * is anything
                Actual: 1,
                  * which is anything
                  * which is anything
                "
            ))))
        )
    }

    #[test]
    fn chained_and_matches() -> Result<()> {
        #[derive(Debug, Clone, Copy)]
        struct Struct {
            a: i32,
            b: i32,
            c: i32,
        }
        verify_that!(
            Struct { a: 1, b: 2, c: 3 },
            field!(Struct.a, eq(1)).and(field!(Struct.b, eq(2))).and(field!(Struct.c, eq(3)))
        )
    }

    #[test]
    fn works_with_str_slices() -> Result<()> {
        verify_that!("A string", starts_with("A").and(ends_with("string")))
    }

    #[test]
    fn works_with_owned_strings() -> Result<()> {
        verify_that!("A string".to_string(), starts_with("A").and(ends_with("string")))
    }
}