[jest-axe] Fix toHaveNoViolations matcher (#39174)

* [jest-axe] Run Prettier

* [jest-axe] Fix toHaveNoViolations matcher

Jest matchers need to return the type of the thing they're matching.

types/jest-axe/index.d.ts

@@ -1,12 +1,13 @@
-// Type definitions for jest-axe 2.2
+// Type definitions for jest-axe 3.2
 // Project: https://github.com/nickcolley/jest-axe
 // Definitions by: Josh Goldberg <https://github.com/JoshuaKGoldberg>
+//                 erbridge <https://github.com/erbridge>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 3.0
 
 /// <reference types="jest" />
 
-import { AxeResults, Result, RunOnly } from "axe-core";
+import { AxeResults, Result, RunOnly } from 'axe-core';
 
 /**
  * Version of the aXe verifier with defaults set.
@@ -34,10 +35,7 @@ export interface AxeOptions {
  * @param options   Options to run aXe.
  * @returns Promise for the results of running aXe.
  */
-export type JestAxe = (
-  html: Element | string,
-  options?: AxeOptions,
-) => Promise<AxeResults>;
+export type JestAxe = (html: Element | string, options?: AxeOptions) => Promise<AxeResults>;
 
 /**
  * Creates a new aXe verifier function.
@@ -82,7 +80,7 @@ export const toHaveNoViolations: {
 declare global {
     namespace jest {
         interface Matchers<R> {
-            toHaveNoViolations: IToHaveNoViolations;
+            toHaveNoViolations(): R;
         }
     }
 

types/jest-axe/jest-axe-tests.ts

@@ -1,4 +1,4 @@
-import { configureAxe, axe, toHaveNoViolations, JestAxe } from "jest-axe";
+import { configureAxe, axe, toHaveNoViolations, JestAxe } from 'jest-axe';
 
 expect.extend(toHaveNoViolations);
 
@@ -9,12 +9,17 @@ const newJestWithOptions: JestAxe = configureAxe({
     iframes: false,
     rules: {},
     runOnly: {
-        type: "rules",
+        type: 'rules',
     },
     selectors: false,
 });
 
 const sameJest: JestAxe = axe;
 
-expect("").toHaveNoViolations();
+expect('').toHaveNoViolations();
 expect(document.body).toHaveNoViolations();
+
+async () => {
+    expect(await Promise.resolve(document.body)).toHaveNoViolations();
+    await expect(Promise.resolve(document.body)).resolves.toHaveNoViolations();
+};