Model-based property checking with Typescript

Property testing: the basics

For an introduction to property-based testing, see the fast-check docs. Fast-check is the state-of-the-art Typescript property testing library.

Model-based property testing

Model-based property testing builds on general property testing techniques to generate pretty much exhaustive test suites for imperative code. For a basic example, see tests/FIFO.test.ts, which is model-based test suite for a FIFO queue. The basic idea is to define a set of commands, which are run on the real system to be tested, and on a model of the system (in this repo all the data structures are modelled by array, but this really depends on what is tested). When a command is run, the model and the

Experiences

Commands are naturally driven by the interface of the system to be tested (see the FIFO queue).
Commands give a natural place to put invariant checks
Care has to be taken with model implementations, since if an error in a model implementation invalidates the whole test suite

DS Wish List:

Linked list
LRU
FIFO
Ring buffer

Resources:

A Simple State-Machine Framework for Property-Based Testing in OCaml by Jan Midtgaard: Concise, to the point, great for someone who already knows what's the deal with property testing, but wants to apply it to imperative code.

John Hughes - Testing the Hard Stuff and Staying Sane: Great examples by John Hughes, the "inventor" of property testing.

Choosing properties for property-based testing: A great cookbook-style article series about property-based testing (not yet applied to this repo, yet).