@semantic-matchers/jest

Customize expect with class-scoped matchers for Jest. Type-specific assertion logic per class, resolved on the prototype chain — chainable with .not, .resolves, and .rejects.

Problem this solves

You might be looking for:

• Class-based / class-scoped matchers — different toX() behavior per domain type
• Type-specific custom matchers without instanceof branches in every matcher
• Expect customization beyond global expect.extend
• Chainable custom assertions (.not, .resolves, .rejects) on class instances
• Page-object or domain matchers — expect(user).toHaveEmail(), expect(button).toBeVisible()
• Polymorphic / dynamic dispatch for Jest assertions

Jest matchers are global by default. This adapter scopes them to classes with full TypeScript inference.

Install

npm install -D @semantic-matchers/jest expect
# or
yarn add -D @semantic-matchers/jest expect

Setup

jest.setup.ts

import '@semantic-matchers/jest/register-types';
import expect from 'expect';
import {installSemanticExpect} from '@semantic-matchers/jest';

installSemanticExpect(expect, {
  global: true,
  exposeOriginalAs: 'jestExpect',
});

Usage

semanticExpect.extend(userMatchers, User);

const user = new User();
user.email = '[email protected]';

expect(user).toHaveEmail('[email protected]');
await expect(Promise.resolve(user)).resolves.toHaveEmail('[email protected]');
expect(user).not.toHaveEmail('[email protected]');

Docs

Full documentation and examples: github.com/dvegap95/semantic-matchers