jestMatchersObject.ts

/**
 * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 */

import {AsymmetricMatcher} from './asymmetricMatchers';
import {Expect, MatchersObject, SyncExpectationResult} from './types';

// Global matchers object holds the list of available matchers and
// the state, that can hold matcher specific values that change over time.
const JEST_MATCHERS_OBJECT = Symbol.for('$$jest-matchers-object');

// Notes a built-in/internal Jest matcher.
// Jest may override the stack trace of Errors thrown by internal matchers.
export const INTERNAL_MATCHER_FLAG = Symbol.for('$$jest-internal-matcher');

if (!(global as any)[JEST_MATCHERS_OBJECT]) {
  Object.defineProperty(global, JEST_MATCHERS_OBJECT, {
    value: {
      matchers: Object.create(null),
      state: {
        assertionCalls: 0,
        expectedAssertionsNumber: null,
        isExpectingAssertions: false,
        suppressedErrors: [], // errors that are not thrown immediately.
      },
    },
  });
}

export const getState = () => (global as any)[JEST_MATCHERS_OBJECT].state;

export const setState = (state: object) => {
  Object.assign((global as any)[JEST_MATCHERS_OBJECT].state, state);
};

export const getMatchers = () => (global as any)[JEST_MATCHERS_OBJECT].matchers;

export const setMatchers = (
  matchers: MatchersObject,
  isInternal: boolean,
  expect: Expect,
) => {
  Object.keys(matchers).forEach(key => {
    const matcher = matchers[key];
    Object.defineProperty(matcher, INTERNAL_MATCHER_FLAG, {
      value: isInternal,
    });

    if (!isInternal) {
      // expect is defined

      class CustomMatcher extends AsymmetricMatcher<[unknown, unknown]> {
        constructor(inverse: boolean = false, ...sample: [unknown, unknown]) {
          super(sample);
          this.inverse = inverse;
        }

        asymmetricMatch(other: unknown) {
          const {pass} = matcher(
            other,
            ...this.sample,
          ) as SyncExpectationResult;

          return this.inverse ? !pass : pass;
        }

        toString() {
          return `${this.inverse ? 'not.' : ''}${key}`;
        }

        getExpectedType() {
          return 'any';
        }

        toAsymmetricMatcher() {
          return `${this.toString()}<${this.sample.join(', ')}>`;
        }
      }

      expect[key] = (...sample: [unknown, unknown]) =>
        new CustomMatcher(false, ...sample);
      if (!expect.not) {
        expect.not = {};
      }
      expect.not[key] = (...sample: [unknown, unknown]) =>
        new CustomMatcher(true, ...sample);
    }
  });

  Object.assign((global as any)[JEST_MATCHERS_OBJECT].matchers, matchers);
};