Add ne matcher

PiperOrigin-RevId: 838323026

Author: Googler

googletest/src/matchers/mod.rs

@@ -45,6 +45,7 @@ mod len_matcher;
 mod lt_matcher;
 mod matches_pattern;
 mod matches_regex_matcher;
+mod ne_matcher;
 mod near_matcher;
 mod none_matcher;
 mod not_matcher;
@@ -84,6 +85,7 @@ pub use le_matcher::le;
 pub use len_matcher::len;
 pub use lt_matcher::lt;
 pub use matches_regex_matcher::matches_regex;
+pub use ne_matcher::ne;
 pub use near_matcher::{approx_eq, near, NearMatcher};
 pub use none_matcher::none;
 pub use not_matcher::not;

googletest/src/matchers/ne_matcher.rs

@@ -0,0 +1,108 @@
+// 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 a value is not equal (in the sense of `!=`) to `expected`.
+///
+/// ```
+/// # use googletest::prelude::*;
+/// # fn should_pass() -> Result<()> {
+/// verify_that!(0, ne(1))?; // Passes
+/// #     Ok(())
+/// # }
+/// # fn should_fail() -> Result<()> {
+/// verify_that!(0, ne(0))?; // Fails
+/// #     Ok(())
+/// # }
+/// # should_pass().unwrap();
+/// # should_fail().unwrap_err();
+/// ```
+pub fn ne<T>(expected: T) -> NEMatcher<T> {
+    NEMatcher { expected }
+}
+
+#[derive(MatcherBase)]
+pub struct NEMatcher<T> {
+    expected: T,
+}
+
+impl<T: Debug, A: Debug + Copy + PartialEq<T>> Matcher<A> for NEMatcher<T> {
+    fn matches(&self, actual: A) -> MatcherResult {
+        (actual != self.expected).into()
+    }
+
+    fn describe(&self, matcher_result: MatcherResult) -> Description {
+        match matcher_result {
+            MatcherResult::Match => format!("is not equal to {:?}", self.expected).into(),
+            MatcherResult::NoMatch => format!("is equal to {:?}", self.expected).into(),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::prelude::*;
+    use crate::Result;
+    use indoc::indoc;
+
+    #[test]
+    fn ne_matches_i32_with_i32() -> Result<()> {
+        verify_that!(123, ne(234))
+    }
+
+    #[test]
+    fn ne_matches_string_reference_with_string_reference() -> Result<()> {
+        verify_that!("A string", ne("B string"))
+    }
+
+    #[test]
+    fn ne_matches_owned_string_with_string_reference() -> Result<()> {
+        let value = "A string".to_string();
+        verify_that!(value, ne("B string"))
+    }
+
+    #[test]
+    fn ne_matches_owned_string_reference_with_string_reference() -> Result<()> {
+        let value = "A string".to_string();
+        verify_that!(&value, ne("B string"))
+    }
+
+    #[test]
+    fn ne_struct_debug_diff() -> Result<()> {
+        #[derive(Debug, PartialEq)]
+        struct Strukt {
+            int: i32,
+            string: String,
+        }
+
+        let result = verify_that!(
+            Strukt { int: 123, string: "something".into() },
+            ne(&Strukt { int: 123, string: "something".into() })
+        );
+        verify_that!(
+            result,
+            err(displays_as(contains_substring(indoc! {
+            "
+            Expected: is not equal to Strukt { int: 123, string: \"something\" }
+            Actual: Strukt { int: 123, string: \"something\" },
+              which is equal to Strukt { int: 123, string: \"something\" }
+            "})))
+        )
+    }
+}