feat(sinon): Make stub factory method optionally generic (#31606)

types/sinon/ts3.1/index.d.ts

@@ -626,10 +626,13 @@ declare namespace Sinon {
     }
 
     interface SinonStubStatic {
+        // Disable rule so assignment to typed stub works (see examples in tests).
         /**
          * Creates an anonymous stub function
          */
-        (): SinonStub;
+        // tslint:disable-next-line no-unnecessary-generics
+        <TArgs extends any[]= any[], R = any>(): SinonStub<TArgs, R>;
+
         /**
          * Stubs all the object’s methods.
          * Note that it’s usually better practice to stub individual methods, particularly on objects that you don’t understand or control all the methods for (e.g. library dependencies).

types/sinon/ts3.1/sinon-tests.ts

@@ -483,6 +483,23 @@ function testStub() {
     stub.withArgs('a', 2).returns(true);
 }
 
+function testTypedStub() {
+    class Foo {
+        bar(baz: number, qux: string): boolean {
+            return true;
+        }
+    }
+    let stub: sinon.SinonStub<[number, string], boolean> = sinon.stub();
+    let stub2 = sinon.stub<[number, string], boolean>();
+    const foo = new Foo();
+    stub = sinon.stub(foo, 'bar');
+    stub2 = sinon.stub(foo, 'bar');
+    const result: boolean = stub(42, 'qux');
+    const fooStub: sinon.SinonStubbedInstance<Foo> = {
+        bar: sinon.stub()
+    };
+}
+
 function testMock() {
     const obj = {};
     const mock = sinon.mock(obj);