Prime Factors Kata in Bash

pf

#!/bin/bash

TEST=${TEST:+'test'}

function prime_factors_of {
    local number=$1

    for (( divisor=2; number > 1; divisor++ )); do
        for (( ; number % divisor == 0; number /= divisor )); do
            prime_factors=("${prime_factors[@]}" $divisor)
        done
    done

    echo "${prime_factors[@]}"
}

function assert_prime_factors_of {
    read result < <(prime_factors_of $1)
    if [ "$result" = "$2" ]; then
        echo -n '.'
    else
        echo -n 'F'
        echo "Failure asserting that $2 are factors of $1" >&2
        echo " -> $2 is expected, $result is returned" >&2
    fi
}

function suite {
    assert_prime_factors_of 1
    assert_prime_factors_of 2 2
    assert_prime_factors_of 3 3
    assert_prime_factors_of 4 "2 2"
    assert_prime_factors_of 5 5
    assert_prime_factors_of 6 "2 3"
    assert_prime_factors_of 7 7
    assert_prime_factors_of 8 "2 2 2"
    assert_prime_factors_of 9 "3 3"
    assert_prime_factors_of $((2 * 3 * 5 * 5 * 7 * 13)) "2 3 5 5 7 13"
}

function report_failing_tests {
    echo -n $1 | tr -d "F" | wc -c | xargs -Ixxx echo -n "xxx passing test(s)"
}

function report_passing_tests {
    echo -n $1 | tr -d "." | wc -c | xargs -Ixxx echo -n "xxx failing test(s)"
}

function report {
    echo $1
    echo "$(report_passing_tests $1), $(report_failing_tests $1)"
}

case $TEST in
    'test')
        echo 'Testing...'
        read suite_result < <(suite)
        report $suite_result
        ;;
    *)
        echo 'Running...'
        prime_factors_of $1
        ;;
esac

You can either use the program with ./pf 2013 or run the tests with TEST=1 ./pf.