15.2.3.10-1 (TestCases/chapter15/15.2/15.2.3/15.2.3.10/15.2.3.10-1.js) Object.preventExtensions throws TypeError if type of first param is not Object On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS ES5Harness.preconditionPassed is true PASS ES5Harness.testPassed is true PASS successfullyParsed is true TEST COMPLETE