Tests);

  function runTests() {
      var epsilon = 1;
      var emToPx = 25;

      ["msub", "msup", "msubsup", "munder", "mover", "munderover",
       "mmultiscripts", "mfrac"].forEach(tag => {
           test(function() {
               assert_true(MathMLFeatureDetection.has_operator_spacing());
               var element = document.getElementsByTagName(tag)[0];
               assert_approx_equals(spaceBeforeElement(element), 2 * emToPx, epsilon);
           }, `${tag} (embellished operator)`);

       