permutations of arrays for jest test.each

permute.js

/**
 * Give all permutations of the values of the given arrays.
 *
 * Each given array implies at least on column in the output. Array elements are spread to create multiple columns.
 * This may yeild variable length elements in the final output.
 */
const permute = (...arrays) =>
    arrays.reduceRight(
        (previous, array) =>
            array.reduce(
                (accumulator, value) => [
                    ...accumulator,
                    ...(previous.length ? previous : [[]]).map(values =>
                        [].concat(value).concat(values),
                    ),
                ],
                [],
            ),
        [],
    );