mutare_gettext

A Mutareextension that teaches mutation testing to read Gettext. It is an extension, not a mutator: it produces no mutations of its own — it only makes Mutare's built-in mutators land correctly on a use Gettext module, without poisoning the single metamutant build.

Install

# mix.exs
def deps do
  [
    {:mutare, "~> 0.1", only: [:dev, :test], runtime: false},
    {:mutare_gettext, "~> 0.1", only: [:dev, :test], runtime: false}
  ]
end

# .mutare.exs
[extensions: [Mutare.Gettext]]

What it does

Gettext (>= 0.26) is two problems for a single-compile mutation tool:

1. use Gettext, backend: MyApp.Gettext registers its backend by mutating the caller module, so Mutare's in-process use expansion raises and never surfaces the import Gettext.Macros it injects — the bare gettext/ngettext calls then never resolve.
2. A message id (gettext("Hello")) must be a compile-time literal; splicing a mutation selector there makes the macro raise while expanding and poisons the build.

The extension fixes both via Mutare's two extension capability behaviours:

• Mutare.UseExpansion (expand_use/3) takes over every use Gettext and injects import Gettext.Macros, so the bare calls resolve.
• Mutare.CallRouting (call_routes/0) routes each macro's arguments per position: the compile-time literals (message id, plural id, domain, context, backend) are :raw (never mutated → no poison), while the runtime arguments — the ngettext plural count and the interpolation bindings — are :expression, so a stale plural threshold or wrong interpolation value still gets caught.

This is a whole-module :raw baseline plus a per-position override for every arity carrying a count/bindings. The overrides are derived from the Gettext macro families (so a position can't drift); the package's test cross-checks each one against the real Gettext.Macros.

Targets Gettext >= 0.26; on older versions it degrades to a harmless no-op.

Development

mix deps.get
mix test
mix check      # format --check-formatted, credo, dialyzer

License

MIT — see LICENSE.