Typing extended-expect

testing-library/jest-dom#123

jest.config.js

@@ -7,7 +7,7 @@ const createJestConfig = nextJest({
 
 // Add any custom config to be passed to Jest
 const customJestConfig = {
-  setupFilesAfterEnv: ['<rootDir>/jest.setup.js'],
+  setupFilesAfterEnv: ['<rootDir>/jest.setup.ts'],
   testEnvironment: 'jest-environment-jsdom',
 };
 

jest.setup.ts

@@ -0,0 +1,16 @@
+// Optional: configure or set up a testing framework before each test.
+// If you delete this file, remove `setupFilesAfterEnv` from `jest.config.js`
+
+// Used for __tests__/testing-library.js
+// Learn more: https://github.com/testing-library/jest-dom
+import '@testing-library/jest-dom';
+
+import type { expect } from '@jest/globals';
+import type { TestingLibraryMatchers } from '@testing-library/jest-dom/matchers';
+
+declare module '@jest/globals' {
+  type Matchers<R = void> = TestingLibraryMatchers<
+    typeof expect.stringContaining,
+    R
+  >;
+}

package.json

@@ -41,6 +41,7 @@
     "@types/node": "18.16.16",
     "@types/react": "18.2.8",
     "@types/react-dom": "18.2.4",
+    "@types/testing-library__jest-dom": "5",
     "@typescript-eslint/eslint-plugin": "^5.59.9",
     "@typescript-eslint/parser": "^5.59.9",
     "eslint": "^8.42.0",