FPSE

Assignment 3: Modules and Testing

For Part I of this assignment you will be writing various modules, module types,
and functors, to better understand how they work. You will also use them
so you have a better idea how they can help in practice.

For Part II you will write your own test suite from scratch, and configure it to use
the Bisect code coverage tool which will verify you have good coverage with your tests. You will also need to document a few invariants in your tests, which we describe below.

As usual we will give two due dates for the two parts.

The file structure

• Use the this zip file for your assignment.
• We are giving you .mli files that describe the expected behavior. We provide a skeleton for some of the code in Part I. Your Part I and II answers will go in the files assignment3/src/finite_group.ml, assignment3/src/ring.ml, assignment3/src/postfix_calc.ml, and assignment3/tests/tests.ml.
• Part I consists of finite_group and ring and your own tests in assignment3/tests/tests.ml, as well as a dune file to run them. For Part I, you need to write some basic tests, and we will just check to make sure you have a couple. The bulk of the testing will be in Part II.
• Part II consists of postfix_calc and your own tests for that file, as well as making sure your overall coverage with bisect is good.

Coverage and Specifications for Part II

• You will need to incorporate the Bisect tool into your dune build file as was described in lecture, and use its output to improve the coverage of your test suite. Test coverage will be a component of your grade.
• Lastly you will need to write a special suite of tests which you will name “Specifications” which asserts five different specifications: either preconditions, postconditions, data structure invariants, or recursion invariants. These properties can be on any functions or data structures defined in any of the files from Part I or Part II. We gave several examples of such propertes in lecture, for example List.rev @@ List.rev l is l for any list l. Such properties are useful to verify with quick-checking, but here you need to just test each property on specific cases. For each spec include a comment stating what the general property is; the test(s) will only test a few instances of the property.

Resources

Here are a few resources to keep in mind to help with this assignment.

• Make sure to review the More Modules lecture notes for Part I.
• If you feel like you need more on the subtleties of information hiding in functors, the Real World OCaml book chapter on functors may be worth looking at.
• For test coverage in part II this was covered in the Specification and Testing Lecture; these notes also contain links to OUnit and Bisect documentation.

Submission and Grading

• As usual, run a final dune clean; dune build and then upload _build/default/assignment3.zip to Gradescope. Note we will be giving you very little information in our report since you need to provide good coverage on your own and not rely on Gradescope. We try not to test anything tricky–we only want to test the functionality as it is precisely described in the assignment, and your own tests should be able to cover this.