code: function accessible() {
    // eslint-disable-next-line no-underscore-dangle
    new chai.Assertion(this._obj).to.be.instanceof(Array);
    // eslint-disable-next-line no-underscore-dangle
    const errors = this._obj
      .filter(test => test.result)
      .reduce((all, test) => all.concat(test.result.violations), [])
      .filter(test => test)
      .map(test => `${JSON.stringify(test, null, 2)}`);
  
    this.assert(
      errors.length === 0,
      `expected no accessibility violations but got:\n\t${errors[0]}`,
      'expected accessibilty errors but received none',
    );
  }
docs: A accessible chai assertion to be paired with browser.axe() tests.