91 lines
2.5 KiB
Rust
91 lines
2.5 KiB
Rust
// Copyright 2022 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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use crate::{
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description::Description,
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matcher::{Matcher, MatcherBase, MatcherResult},
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};
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use std::fmt::Debug;
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/// Matches an empty container.
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///
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/// `T` can be any container that implements `IntoIterator`. For instance, `T`
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/// can be the reference of a common container like `&Vec` and
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/// [`&HashSet`][std::collections::HashSet].
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///
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/// ```
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/// # use googletest::prelude::*;
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/// # use std::collections::HashSet;
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/// # fn should_pass() -> Result<()> {
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/// let value: Vec<i32> = vec![];
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/// verify_that!(value, is_empty())?;
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/// let value: HashSet<i32> = HashSet::new();
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/// verify_that!(value, is_empty())?;
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/// let value: &[u32] = &[];
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/// verify_that!(value, is_empty())?;
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/// # Ok(())
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/// # }
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/// # should_pass().unwrap();
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/// ```
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pub fn is_empty() -> EmptyMatcher {
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EmptyMatcher
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}
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#[derive(MatcherBase)]
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pub struct EmptyMatcher;
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impl<T: Debug + Copy> Matcher<T> for EmptyMatcher
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where
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T: IntoIterator,
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{
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fn matches(&self, actual: T) -> MatcherResult {
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actual.into_iter().next().is_none().into()
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}
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fn describe(&self, matcher_result: MatcherResult) -> Description {
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if matcher_result.into() { "is empty" } else { "isn't empty" }.into()
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}
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}
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#[cfg(test)]
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mod tests {
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use crate::prelude::*;
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use crate::Result;
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use std::collections::HashSet;
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#[test]
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fn empty_matcher_match_empty_vec() -> Result<()> {
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let value: Vec<i32> = vec![];
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verify_that!(value, is_empty())
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}
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#[test]
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fn empty_matcher_does_not_match_empty_vec() -> Result<()> {
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let value = vec![1, 2, 3];
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verify_that!(value, not(is_empty()))
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}
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#[test]
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fn empty_matcher_matches_empty_slice() -> Result<()> {
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let value: &[i32] = &[];
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verify_that!(value, is_empty())
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}
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#[test]
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fn empty_matcher_matches_empty_hash_set() -> Result<()> {
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let value: HashSet<i32> = HashSet::new();
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verify_that!(value, is_empty())
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}
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}
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