build(rust): vendor googletest crate

third_party/crates/googletest-0.14.3/src/matchers/empty_matcher.rs

@@ -0,0 +1,90 @@
+// 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.
+
+use crate::{
+    description::Description,
+    matcher::{Matcher, MatcherBase, MatcherResult},
+};
+use std::fmt::Debug;
+
+/// Matches an empty container.
+///
+/// `T` can be any container that implements `IntoIterator`. For instance, `T`
+/// can be the reference of a common container like `&Vec` and
+/// [`&HashSet`][std::collections::HashSet].
+///
+/// ```
+/// # use googletest::prelude::*;
+/// # use std::collections::HashSet;
+/// # fn should_pass() -> Result<()> {
+/// let value: Vec<i32> = vec![];
+/// verify_that!(value, is_empty())?;
+/// let value: HashSet<i32> = HashSet::new();
+/// verify_that!(value, is_empty())?;
+/// let value: &[u32] = &[];
+/// verify_that!(value, is_empty())?;
+/// #     Ok(())
+/// # }
+/// # should_pass().unwrap();
+/// ```
+pub fn is_empty() -> EmptyMatcher {
+    EmptyMatcher
+}
+
+#[derive(MatcherBase)]
+pub struct EmptyMatcher;
+
+impl<T: Debug + Copy> Matcher<T> for EmptyMatcher
+where
+    T: IntoIterator,
+{
+    fn matches(&self, actual: T) -> MatcherResult {
+        actual.into_iter().next().is_none().into()
+    }
+
+    fn describe(&self, matcher_result: MatcherResult) -> Description {
+        if matcher_result.into() { "is empty" } else { "isn't empty" }.into()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::prelude::*;
+    use crate::Result;
+    use std::collections::HashSet;
+
+    #[test]
+    fn empty_matcher_match_empty_vec() -> Result<()> {
+        let value: Vec<i32> = vec![];
+        verify_that!(value, is_empty())
+    }
+
+    #[test]
+    fn empty_matcher_does_not_match_empty_vec() -> Result<()> {
+        let value = vec![1, 2, 3];
+        verify_that!(value, not(is_empty()))
+    }
+
+    #[test]
+    fn empty_matcher_matches_empty_slice() -> Result<()> {
+        let value: &[i32] = &[];
+        verify_that!(value, is_empty())
+    }
+
+    #[test]
+    fn empty_matcher_matches_empty_hash_set() -> Result<()> {
+        let value: HashSet<i32> = HashSet::new();
+        verify_that!(value, is_empty())
+    }
+}