prng.bats

#!/usr/bin/env bats

# shellcheck disable=1083
true

# shellcheck source=../parallel_opts.sh
. "${BATS_TEST_DIRNAME}/../examples/script_that_sometimes_fails.sh"

@test 'prng produces a uniform distribution with a single zero, and has entropy' {
    # shellcheck disable=2034
    SLURM_NTASKS=5

    not_sorted=0
    for seed in {0..9}
    do
	result=()
	num_zeros=0
	for ID in {0..4}
	do
	    x=$(prng)
	    if (( x % SLURM_NTASKS == 0 ))
	    then
		num_zeros=$(( num_zeros + 1 ))
	    fi
	    result[ID]=$x
	done
	echo "seed: $seed, prng: ${result[*]}, num_zeros: $num_zeros"
	[[ $num_zeros -eq 1 ]]
	# Verify it contains all the values / is a uniform distribution.
	expected=( $(seq 0 4) )
	IFS=$'\n' sorted=($(sort <<<"${result[*]}"))
	unset IFS
	[[ "${sorted[*]}" = "${expected[*]}" ]]
	if [[ "${sorted[*]}" != "${result[*]}" ]]
	then
	    not_sorted=$(( not_sorted + 1))
	fi
    done
    # Check for entropy.
    echo "not_sorted: $not_sorted"
    [ $not_sorted -ge 6 ]
}