JSFiddle - React, Tailwind, and code Playground

HTML

<div id="output"></div>

JavaScript

(function () {

  // A simple JavaScript test framework.
  //
  // > Your app is complex. Testing it should be simple. --Isaac Newton
  //
  // - http://en.wikipedia.org/wiki/Occam's_razor
  // - http://en.wikipedia.org/wiki/Worse_is_better
  // - http://en.wikipedia.org/wiki/KISS_principle
  // - http://en.wikipedia.org/wiki/Unix_philosophy

  var suite, test, assert, defaultPrinter;

  defaultPrinter = function () {
    console.log(this.passed, this.name);
  };

  suite = function (description, callback, printer) {
    var context = { name: [description] };
    context.printer = printer || defaultPrinter;
    callback.call(context);
  };

  assert = function (self, description, value) {
    self.printer.call({
      name: self.name.concat([description]),
      passed: !!value
    });
  };

  test = function (self, description, callback) {
    var context = { printer: self.printer };
    context.name = self.name.concat([description]);
    callback.call(context);
  };

  // Usage Example
 
  // want to change the printed output?
  var htmlPrinter = function () {
    var status = this.passed ? "PASS" : "FAIL";
    var message = status + ": " + this.name.join(" ");
    document.getElementById("output").innerHTML += message + "<br>";
  };

  suite("contrived example", function () {
    test(this, "auto", function () {
      test(this, "car", function () {
        assert(this, "has engine", true);
        assert(this, "has 4 wheels", true);
        assert(this, "can accelerate", true);
        assert(this, "can stop", true);

        test(this, "yugo", function () {
          // async example
          var yugo = this;
          setTimeout(function () {
            assert(yugo, "is slow", true);
          }, 1000);

          assert(this, "is crappy", true);
        });

        test(this, "mustang", function () {
          assert(this, "is fast", true);
          assert(this, "is fun", true);
        });
      });

      test(this, "truck", function () {
       ...