This makeup is still in draft form.

A few of you had some significant problems on exam 2. Since there were unit tests for exam 2, I don't think that a makeup that simply asks you to correct your already buggy implementations is appropriate. I've also had very little luck with such makeup examinations. Hence, this makeup primarily asks you to reflect in new ways on a few issues from the examination.

Policies and other notes

• The makeup is due in electronic form at 10:30 p.m. on Thursday, 10 April
  1. The makeup is due in printed form at 10:00 a.m. on Friday, 11 April 2014.
• Each makeup problem is worth at most 1/2 point on the examination's 4-point scale.
• You cannot increase your grade on the examination beyond a grade of B+.
• You may do no makeup problems, all of the makeup problems, or some of the makeup problems.
• You need not return your examination to me.
• You may not put your work in a public GitHub repository.
• I would prefer that you email me a tarball of your code that unpacks into a directory that corresponds to your user name. However, I will also accept an email that just contains the .java and .md files.
• You must follow the same academic honesty policies.
• You must submit another academic honesty statement.
• You will not get credit if you format the code incorrectly or fail to comment your end braces.

Additional issues

• Grading your makeup examinations will be low priority. It may not happen until after the end of the semester.
• I reserve the right to change any and all policies regarding this makeup.

Preparation

Clone the repository at https://github.com/Grinnell-CSC207/makeup2-2014S.

Makeup Problem 1

As the examination suggested, I try to use some interesting approaches in my unit tests. For this problem, you need to explore and explain a few of those approaches. Your goal is to explain the approaches to someone who hasn't seen my code, but wants guidance in strategies for writing more sophisticated unit tests. You can treat them as if they are 'blog posts.

a. Explain how one might use factories in writing unit tests. You may need to teach yourself about factories in order to complete this problem.

b. Explain at least two ways in which one might use permutations in testing. For example, you might explain about randomized permutations and all permutations.

Makeup Problem 2

In the repository, you will find two implementations of filtered iterators, along with a skeletal set of unit tests. Both implementations passed my unit tests, but one has a large number of flaws. Your goal is to write a set of tests that will identify some of those flaws. (I believe that the good implementation is correct; you will get extra credit if you identify flaws in that implementation.) Your tests must illustrate the following flaws:

• It is possible to make next return null, even when null is not in the underlying collection. Put a test that reveals this issue in testNext1.
• There are other situations (sequences of operations) in which next correctly returns some values in the underlying iterator and only returns values in the underlying iterator that meet the predicate, but fails to return the correct value for some of the calls to next.
  • Some of those situations are primarily caused by a flaw in next, rather than a flaw in hasNext or remove. Put a test that reveals this issue in testNext2.
  • Some of thosse situations are primarily caused by a flaw in hasNext. Put a test that reveals this issue in testNext3.
• It is possible to make remove remove the wrong element (that is, something other than what was most recently returned by next). Put a test that reveals this issue in testRemove1. Note that the problem might be that the code calls base.remove() when it should be throwing an exception.
• It is possible to make hasNext return the wrong value (either true when there should not be remaining elements, or false when there should be remaining elements). Put a test that reveals this issue in testHasNext1.

Ideally, you will find that BadFilteredIterator fails these five tests (and passes the two sample tests) and that GoodFilteredIterator passes all the tests.