Arithmetic operator mutators

Returns a ready-made list of operator() mutators covering common arithmetic swaps: +/-, *//, ^/*, %%/*, %/%//.

Usage

arithmetic_operators()

Value

A list of operator() mutators.

Details

Use on any file that performs calculations. A surviving mutant from this preset typically means an assertion checks a property of the result (sign, order) rather than a specific value — replacing expect_gte() with expect_equal() and a computed expected value usually kills it.

See also

vignette("mutators", package = "muttest") for the full operator table and a worked example showing the direction-insensitive assertion pattern.

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

Examples

arithmetic_operators()
#> [[1]]
#> Mutator: + → -
#> Query: (binary_operator
#>       lhs: (_) @lhs
#>       operator: _ @operator
#>       rhs: (_) @rhs
#>       (#eq? @operator "+")
#>     )
#> 
#> [[2]]
#> Mutator: - → +
#> Query: (binary_operator
#>       lhs: (_) @lhs
#>       operator: _ @operator
#>       rhs: (_) @rhs
#>       (#eq? @operator "-")
#>     )
#> 
#> [[3]]
#> Mutator: * → /
#> Query: (binary_operator
#>       lhs: (_) @lhs
#>       operator: _ @operator
#>       rhs: (_) @rhs
#>       (#eq? @operator "*")
#>     )
#> 
#> [[4]]
#> Mutator: / → *
#> Query: (binary_operator
#>       lhs: (_) @lhs
#>       operator: _ @operator
#>       rhs: (_) @rhs
#>       (#eq? @operator "/")
#>     )
#> 
#> [[5]]
#> Mutator: ^ → *
#> Query: (binary_operator
#>       lhs: (_) @lhs
#>       operator: _ @operator
#>       rhs: (_) @rhs
#>       (#eq? @operator "^")
#>     )
#> 
#> [[6]]
#> Mutator: %% → *
#> Query: (binary_operator
#>       lhs: (_) @lhs
#>       operator: _ @operator
#>       rhs: (_) @rhs
#>       (#eq? @operator "%%")
#>     )
#> 
#> [[7]]
#> Mutator: %/% → /
#> Query: (binary_operator
#>       lhs: (_) @lhs
#>       operator: _ @operator
#>       rhs: (_) @rhs
#>       (#eq? @operator "%/%")
#>     )
#> 

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