Counter

Various approaches for stateful property testing with stream_data and PropCheck (i.e. PropEr).

The main system under test is the Counter, which is a simple counting process with a reset function (clear()).

The initial models are state machines, which distinguish between the initial state, the zero state and the one state, which maps all counting values above zero into one state to make it easier to reason about the counting. The state machine is shown in the following image:

A second system under test is the sequential cache, ported from Proper Testing in Erlang to Elixir. The test cases are a direct translation to PropCheck and StreamData.

Open issues of the StreamData based implementation

• the history cannot be inspected easily
• aggregation of commands is missing (generally in StreamData)

Installation

If available in Hex, the package can be installed by adding counter to your list of dependencies in mix.exs:

def deps do
  [
    {:counter, "~> 0.1.0"}
  ]
end

Documentation can be generated with ExDoc and published on HexDocs. Once published, the docs can be found at https://hexdocs.pm/counter.