Index mutation mutators

Returns a ready-made list of index_increment() and index_decrement() mutators that shift every simple subscript index by 1.

Usage

index_mutations()

Value

A list of mutators.

Details

Use on any file that extracts elements from vectors or lists by position. Surviving mutants reveal off-by-one errors where tests only verify that something was extracted, not which element — asserting the exact value of the extracted element kills them.

See also

vignette("mutators", package = "muttest") for the full mutator table.

vignette("interpreting-results", package = "muttest") for how to diagnose survivors and fix the underlying test weakness.

Examples

index_mutations()
#> [[1]]
#> Mutator: x[<i>] → x[<i> + 1L]
#> Query: [(subset arguments: (arguments (argument value: [(identifier) (float) (integer)] @index))) (subset2 arguments: (arguments (argument value: [(identifier) (float) (integer)] @index)))]
#> 
#> [[2]]
#> Mutator: x[<i>] → x[<i> - 1L]
#> Query: [(subset arguments: (arguments (argument value: [(identifier) (float) (integer)] @index))) (subset2 arguments: (arguments (argument value: [(identifier) (float) (integer)] @index)))]
#> 

if (FALSE) { # \dontrun{
plan <- muttest_plan(
  source_files = "R/selectors.R",
  mutators = index_mutations()
)
muttest(plan, "tests/testthat")
} # }