Merge pull request #23102 from JoshuaKGoldberg/jest-class-names-describe

Allowed functions in jest's describe

types/jest/index.d.ts

@@ -11,6 +11,7 @@
 //                 Jamie Mason <https://github.com/JamieMason>
 //                 Douglas Duteil <https://github.com/douglasduteil>
 //                 Ahn <https://github.com/AhnpGit>
+//                 Josh Goldberg <https://github.com/joshuakgoldberg>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.3
 
@@ -201,6 +202,10 @@ declare namespace jest {
 
     type Lifecycle = (fn: ProvidesCallback, timeout?: number) => any;
 
+    interface FunctionLike {
+        readonly name: string;
+    }
+
     /**
      * Creates a test closure
      */
@@ -222,7 +227,8 @@ declare namespace jest {
     }
 
     interface Describe {
-        (name: string, fn: EmptyFunction): void;
+        // tslint:disable-next-line ban-types
+        (name: number | string | Function | FunctionLike, fn: EmptyFunction): void;
         only: Describe;
         skip: Describe;
     }

types/jest/jest-tests.ts

@@ -10,6 +10,10 @@ declare const $: any;
 // Tests based on the Jest website
 jest.unmock('../sum');
 
+class TestClass { }
+
+describe(TestClass, () => { });
+
 describe('sum', () => {
     it('adds 1 + 2 to equal 3', () => {
         const sum: (a: number, b: number) => number = require('../sum');