code: function (testObject) {
          if (testObject instanceof YUITest.TestSuite || testObject instanceof YUITest.TestCase) {
              this.items.push(testObject);
          }
          return this;
      }
docs: Adds a test suite or test case to the test suite.
  @param {YUITest.TestSuite||YUITest.TestCase} testObject The test suite or test case to add.
  @return {Void}
  @method add