fix: not to break on expect matcher extension overwrite

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 ### Fixes
 
+- `[expect]` Make expect extension properties `configurable`
+
 ### Chore & Maintenance
 
 - `[jest-config, jest-util]` Use `ci-info` instead of `is-ci` to detect CI environment ([11973](https://github.com/facebook/jest/pull/11973))

packages/expect/src/__tests__/extend.test.ts

@@ -167,3 +167,21 @@ it('prints the Symbol into the error message', () => {
     }),
   ).toThrowErrorMatchingSnapshot();
 });
+
+it('allows overriding existing extension', () => {
+  jestExpect.extend({
+    toAllowOverridingExistingMatcher(_expected: unknown) {
+      return {pass: _expected === 'bar'};
+    },
+  });
+
+  jestExpect('foo').not.toAllowOverridingExistingMatcher();
+
+  jestExpect.extend({
+    toAllowOverridingExistingMatcher(_expected: unknown) {
+      return {pass: _expected === 'foo'};
+    },
+  });
+
+  jestExpect('foo').toAllowOverridingExistingMatcher();
+});

packages/expect/src/jestMatchersObject.ts

@@ -99,12 +99,18 @@ export const setMatchers = <State extends MatcherState = MatcherState>(
       }
 
       Object.defineProperty(expect, key, {
+        configurable: true,
+        enumerable: true,
         value: (...sample: [unknown, ...Array<unknown>]) =>
           new CustomMatcher(false, ...sample),
+        writable: true,
       });
       Object.defineProperty(expect.not, key, {
+        configurable: true,
+        enumerable: true,
         value: (...sample: [unknown, ...Array<unknown>]) =>
           new CustomMatcher(true, ...sample),
+        writable: true,
       });
     }
   });