Jasmine Custom Matcher - toBeSimilar

toBeSimilar.js

// test that numbers are similar with a tolerance of 0.1

var customMatchers = {
  toBeSimilar: (util, tester) => {

    const tolerance = 0.1;

    return {
      compare: (actual, expected) => {
        return {
          pass: (Math.abs(actual - expected) < tolerance),
          message: `Expected ${actual} to be ${expected}`
        }
      }
    }
  }
};

beforeEach(function() {
  jasmine.addMatchers(customMatchers);
});