responsive_image_grid/tests/e2e/custom-assertions/elementCount.js

/**
 * A custom Nightwatch assertion. The assertion name is the filename.
 *
 * Example usage:
 *   browser.assert.elementCount(selector, count)
 *
 * For more information on custom assertions see:
 *   https://nightwatchjs.org/guide/extending-nightwatch/#writing-custom-assertions
 *
 *
 * @param {string|object} selectorOrObject
 * @param {number} count
 */

exports.assertion = function elementCount(selectorOrObject, count) {
  let selector

  // when called from a page object element or section
  if (typeof selectorOrObject === 'object' && selectorOrObject.selector) {
    // eslint-disable-next-line prefer-destructuring
    selector = selectorOrObject.selector
  } else {
    selector = selectorOrObject
  }

  this.message = `Testing if element <${selector}> has count: ${count}`
  this.expected = count
  this.pass = (val) => val === count
  this.value = (res) => res.value
  function evaluator(_selector) {
    return document.querySelectorAll(_selector).length
  }
  this.command = (cb) => this.api.execute(evaluator, [selector], cb)
}