Custom matcher for Jasmine - matcher for a list of strings to have (at least) one that matches a given regex.

1_toContainRegexMatcher.js

const toContainRegexMatcher = {
  // see https://jasmine.github.io/tutorials/custom_matcher
  // for docs on the factory that returns a matcher.
  'toContainRegex': function(util, customEqualityTesters) {
    return {
      'compare': function(actual, regex) {
        if (!(regex instanceof RegExp)) {
          throw `toContainRegex expects a regex, got ${JSON.stringify(regex)}`;
        }
        let result = {};

        if (!actual || !actual.length) {
          result.pass = false;
          result.message = `Expected ${actual} to be a non-empty array `+
                           `containing something matching ${regex}`;
          return result;
        }
        for (let s of actual) {
          if (s.match && s.match(regex)) {
            result.pass = true;
            // craft the message for the negated version (i.e. using .not)
            result.message = `Expected ${actual} not to have anyting `+
                             `matching ${regex}, but ${s} did`;
            return result;
          }
        }
        result.message = `Expected ${actual} to have something matching ${regex}`;
        result.pass = false;
        return result;
      },
    };
  },
};

2_example.spec.js

describe('my thing', function() {
  beforeEach(function() {
    jasmine.addMatchers(toContainRegexMatcher);
  });
  
  it('does some sort of test', function() {
    expect(['alpha', 'beta', 'gamma']).toContainRegex(/.*et.*/);
    expect(['alpha', 'beta', 'gamma']).not.toContainRegex(/golf.*/);
  });
});

3_LICENSE

Copyright 2018 Google LLC

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.