Mutest::Meta::Example.add :array do source '[true]' singleton_mutations mutation 'true' mutation '[false]' mutation '[]' end Mutest::Meta::Example.add :array do source '[true, false]' singleton_mutations # Mutation of each element in array mutation '[false, false]' mutation '[true, true]' # Remove each element of array once mutation '[true]' mutation '[false]' # Empty array mutation '[]' end