Stateful unit testing using Jqwik actions: fixed-size circular queue

In this project, we'll implement and thoroughly test our own array-based data structure, a fixed-size circular queue!

Objectives

An understanding of the following concepts and techniques:

• ADT implementation perspective
• queue ADT (see also java.util.Queue)
• implementing queue as a circular array
• queues with fixed versus growing capacity
• algorithms based on the queue's FIFO policy
• interface-based testing
• stateful property-based testing
• initial exposure to concurrency

Instructions

In this project, you will have the opportunity to implement a generic queue as a circular array and use this implementation in the context of a typical queue-based application.

Specifically:

1. Complete the TODO items in the FixedArrayQueue implementation until the tests in TestSimpleQueue pass.
2. Complete the main class SingleQueueService, which reads successive input lines until EOF and puts them on a queue that the background consumer activity processes.
3. When running the main class, note that the consumer is set to serve customers at a fixed rate. By entering customers' names at different rates, try to create scenarios where customers arrive infrequently enough for the queue to remain empty, or in such quick succession that the queue becomes full (by pasting several of them at once).
4. Complete the TODO items in the TestSimpleQueueJqwik test suite until it reflects the stated pre- and postconditions of the SimpleQueue methods.
5. Answer the following questions in a separate file Answers.md:
   • Why does FixedArrayQueue require an explicit constructor?
   • What happens when you offer an item to a full FixedArrayQueue?
   • What happens when you poll an empty FixedArrayQueue?
   • What is the time and (extra) space complexity of each of the FixedArrayQueue methods?
   • How exhaustively does the TestSimpleQueue test suite test the implementation, both conceptually and in terms of actual coverage?
   • How exhaustively does the TestSimpleQueueJqwik test suite test the implementation, both conceptually and in terms of actual coverage?
   • What kind of test cases does the simpleQueueActions method generate?

Running the code

To run the tests:

mvn verify

To run the main program:

mvn exec:java

Grading (total 6 points)

• 2 completion of items marked TODO in FixedArrayQueue and existing JUnit tests passing
• 1 completion of SingleQueueService and correct behavior
• 2 completion of items marked TODO in TestSimpleQueueJqwik and working
• 1 written part
  • 0.8 responses to the questions above
  • 0.2 grammar, style, formatting

Extra credit

Clearly indicate in your Answers.md file any extra credit attempted.

• 0.2 add a working CI status badge for your project
• 0.3 apply checkSimpleQueue property to different queue capacities
• 0.3 add observable data invariant(s) for 0 <= size <= capacity to the checkSimpleQueue property
• 0.5 add a clear method, which removes all elements in the queue, to interface, impmlementation, and tests

References

• java.util.Queue interface
• Introduction and Array Implementation of Circular Queue
• Zombies testing
• Zombies testing with circular queue/buffer example