jsdoc/packages/jsdoc-test-matchers/index.js

const { addMatchers } = require('add-matchers');

require('jasmine-expect');

addMatchers({
  toBeError(value) {
    return value instanceof Error;
  },
  toBeErrorOfType(other, value) {
    return value instanceof Error && value.name === other;
  },
  toBeInstanceOf(other, value) {
    let otherName;
    let valueName;

    if (typeof value !== 'object') {
      throw new TypeError(`Expected object value, got ${typeof value}`);
    }

    valueName = value.constructor.name;

    // Class name.
    if (typeof other === 'string') {
      otherName = other;
      // Class constructor.
    } else if (typeof other === 'function') {
      otherName = other.name;
    } else {
      otherName = other.constructor.name;
    }

    return valueName === otherName;
  },
});