Mutix

Mutation testing tool for Elixir

Mutix is a mutation testing tool that generates mutations of your source files and runs the existing test suite against them.

Generates a mutation report along with a mutation score as the result.

Installation

Add :mutix to your test dependencies in your mix.exs file:

def deps do
  [
    {:mutix, git: "https://github.com/tuomohopia/mutix.git", tag: "v0.1.1", only: [:dev, :test]}
  ]
end

Then add :test as the preferred MIX_ENV for the mix task of mutix in your mix.exs file:

def project do
  preferred_cli_env: [
    mutate: :test
  ]

Or optionally

def cli do
    [preferred_envs: [mutate: :test]]
end

The mix task takes a source file to mutate as the required parameter.

mix mutate lib/parser.ex

Run mix help mutate to see instructions on how to use the tool.

--from - which target operator to mutate
--to - which operator should the target operator be mutated to in the source file

If --from and --to are not defined, --from defaults to + and --to to -.

mix mutate lib/parser.ex --from ">" --to "<"

mix mutate lib/parser.ex --from and --to not

The current version comes with the following caveats:

Macros: Mutates operators even inside macros. This can lead to very confusing results
Single source: Only mutates a single source file at a time. This is because producing mutations and running the test suite on each one of them is computationally expensive and this is not optimized yet