rebar3_mutate

Mutation testing plugin for rebar3. Systematically applies small code transformations (mutants) and runs your tests to verify they catch them.

Installation

Add to project_plugins in your rebar.config:

{project_plugins, [rebar3_mutate]}.

Run against all modules:

rebar3 mutate

Target specific modules:

rebar3 mutate -m my_module,my_other_module

Exclude modules:

rebar3 mutate -x generated_module,test_helper

Select specific operators:

rebar3 mutate -o op_arithmetic,op_boolean

Set a per-mutant timeout:

rebar3 mutate -t 10000

Use Common Test instead of EUnit:

rebar3 mutate -f ct

Enforce a minimum score in CI:

rebar3 mutate -s 80.0

Output JSON for CI integration:

rebar3 mutate --format json

Control parallelism:

rebar3 mutate -w 4

Flag	Short	Description	Default
`--module`	`-m`	Target module(s), comma-separated	all
`--exclude`	`-x`	Modules to exclude, comma-separated	none
`--operators`	`-o`	Mutation operators to use, comma-separated	all
`--timeout`	`-t`	Per-mutant timeout in milliseconds	5000
`--test-framework`	`-f`	Test framework: `eunit` or `ct`	eunit
`--min-score`	`-s`	Minimum mutation score (0-100), fail if below	none
`--format`		Output format: `console` or `json`	console
`--workers`	`-w`	Number of parallel workers	scheduler count

Operator	Mutations
`op_arithmetic`	`+` <-> `-`, `*` <-> `div`, `rem` <-> `div`
`op_relational`	`>` <-> `<`, `>=` <-> `=<`, `=:=` <-> `=/=`, `==` <-> `/=`
`op_boolean`	`andalso` <-> `orelse`, `true` <-> `false`
`op_return_value`	`ok` <-> `error` atoms and tuples
`op_statement_delete`	Replace function calls with `ok`
`op_constant`	Integer N -> N+1, N-1, 0
`op_negate_condition`	Wrap `andalso`/`orelse` with `not`, remove existing `not`
`op_list`	`++` <-> `--`, `hd` <-> `tl`

During execution, a per-mutant progress indicator is printed to stderr:

The plugin reports:

The mutation score is the percentage of mutants killed. A higher score means your tests are more effective at catching regressions.

MIT -- see LICENSE.