Add Mapping::contains (#2133)

* Add Mapping::contains

* Fix typo

* Add a changelog entry

* Use PyAny::contatins instead

* Update mapping.rs

CHANGELOG.md

@@ -30,6 +30,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add check for correct number of arguments on magic methods. [#2083](https://github.com/PyO3/pyo3/pull/2083)
 - `wrap_pyfunction!` can now wrap a `#[pyfunction]` which is implemented in a different Rust module or crate. [#2091](https://github.com/PyO3/pyo3/pull/2091)
 - Add `PyAny::contains` method (`in` operator for `PyAny`). [#2115](https://github.com/PyO3/pyo3/pull/2115)
+- Add `PyMapping::contains` method (`in` operator for `PyMapping`). [#2133](https://github.com/PyO3/pyo3/pull/2133)
 
 ### Changed
 

src/types/mapping.rs

@@ -33,6 +33,16 @@ impl PyMapping {
         self.len().map(|l| l == 0)
     }
 
+    /// Determines if the mapping contains the specified key.
+    ///
+    /// This is equivalent to the Python expression `key in self`.
+    pub fn contains<K>(&self, key: K) -> PyResult<bool>
+    where
+        K: ToBorrowedObject,
+    {
+        PyAny::contains(self, key)
+    }
+
     /// Gets the item in self with key `key`.
     ///
     /// Returns an `Err` if the item with specified key is not found, usually `KeyError`.
@@ -166,6 +176,21 @@ mod tests {
         });
     }
 
+    #[test]
+    fn test_contains() {
+        Python::with_gil(|py| {
+            let mut v = HashMap::new();
+            v.insert("key0", 1234);
+            let ob = v.to_object(py);
+            let mapping = <PyMapping as PyTryFrom>::try_from(ob.as_ref(py)).unwrap();
+            mapping.set_item("key1", "foo").unwrap();
+
+            assert!(mapping.contains("key0").unwrap());
+            assert!(mapping.contains("key1").unwrap());
+            assert!(!mapping.contains("key2").unwrap());
+        });
+    }
+
     #[test]
     fn test_get_item() {
         Python::with_gil(|py| {