operator: Mutate a binary operator

In muttest: Mutation Testing

Mutate a binary operator

Description

Produces one mutant per occurrence of from in the source file, replacing it with to. A surviving mutant means your tests cannot distinguish the original operator from the replacement — pointing at the missing assertion or input value.

Usage

operator(from, to)

Arguments

from	The operator to replace (e.g. "+", "==", ">").
to	The replacement operator.

Details

Use this when you need a specific swap not covered by the preset collections (arithmetic_operators(), comparison_operators(), logical_operators()).

Value

A Mutator object.

See Also

comparison_operators(), arithmetic_operators(), logical_operators() for ready-made preset lists.

vignette("mutators", package = "muttest") for the full operator reference with examples of what each preset catches.

vignette("interpreting-results", package = "muttest") to learn how to read surviving mutants and strengthen the tests they expose.

Examples

operator("+", "-")
operator("==", "!=")
operator(">", ">=")  # probe the strict vs. non-strict boundary

muttest documentation built on May 14, 2026, 5:10 p.m.