fix(expect): allow expect.Matchers generic with single value (#11986)

Author: mxschmitt

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 ### Fixes
 
+- `[expect]` Allow again `expect.Matchers` generic with single value ([#11986](https://github.com/facebook/jest/pull/11986))
+
 ### Chore & Maintenance
 
 ### Performance

packages/expect/src/index.ts

@@ -431,7 +431,7 @@ const expectExport = expect as Expect;
 
 declare namespace expectExport {
   export type MatcherState = JestMatcherState;
-  export interface Matchers<R, T> extends MatcherInterface<R, T> {}
+  export interface Matchers<R, T = unknown> extends MatcherInterface<R, T> {}
 }
 
 export = expectExport;

test-types/expect.test.ts

@@ -0,0 +1,13 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import type * as expect from 'expect';
+
+export type M = expect.Matchers<void, unknown>;
+export type N = expect.Matchers<void>;
+// @ts-expect-error
+export type E = expect.Matchers<>;