Bash test: get the directory of a script

unit.sh

#!/bin/bash

# Following stackoverflow discussion, from https://gist.github.com/tvlooy/cbfbdb111a4ebad8b93e (rev7)

function test(){
    local __MESSAGE__="$1"
    local __RECEIVED__="$2"
    local __EXPECTED__="$3"

    if [ "${__RECEIVED__}" == "${__EXPECTED__}" ]; then
        # shellcheck disable=SC1117
        echo -e "\033[32m✔ Tested ${__MESSAGE__}"
    else
        # shellcheck disable=SC1117
        echo -e "\033[31m✘ Tested ${__MESSAGE__}"
        echo -e "  Received: ${__RECEIVED__}"
        echo -e "  Expected: ${__EXPECTED__}"
    fi
    # shellcheck disable=SC1117
    echo -en "\033[0m"
}

function testSuite(){
    test 'absolute call'                "$(bash ${__TEMPDIR__}/1234/test.sh)"         "${__TEMPDIR__}/1234"
    test 'via symlinked dir'            "$(bash ${__TEMPDIR__}/current/test.sh)"      "${__TEMPDIR__}/1234"
    test 'via symlinked file'           "$(bash ${__TEMPDIR__}/test.sh)"              "${__TEMPDIR__}/1234"
    test 'via multiple symlinked dirs'  "$(bash ${__TEMPDIR__}/current/loop/test.sh)" "${__TEMPDIR__}/1234"
    pushd "${__TEMPDIR__}" >/dev/null || exit 1
    test 'relative call'                "$(bash 1234/test.sh)"                        "${__TEMPDIR__}/1234"
    popd >/dev/null       || exit 1
    test 'with space in dir'            "$(bash ${__TEMPDIR__}/12\ 34/test.sh)"       "${__TEMPDIR__}/1234"
    test 'with space in file'           "$(bash ${__TEMPDIR__}/1234/te\ st.sh)"       "${__TEMPDIR__}/1234"
    echo
}

function readlink_exists(){
    if [[ ! $(which readlink 2> /dev/null) ]]
    then
        # shellcheck disable=SC1117
        echo -e "\033[31m✘ readlink not available, test skipped"
        # shellcheck disable=SC1117
        echo -e "\033[0m"
        (exit 1)
    fi;
}

function rm_tempdir(){
    [[ -n "${__TEMPDIR__}"  && -d "${__TEMPDIR__}" ]]\
        && rm -fr "${__TEMPDIR__}";
}

function set_tempdir(){
    rm_tempdir;

    while [[ -z "${__TEMPDIR__}" || -d "${__TEMPDIR__}" ]]; do
        __TEMPDIR__="/tmp/${BASH_SOURCE[0]}_temp.${USER}.${RANDOM}";
    done;

    mkdir -p "${__TEMPDIR__}"
}

function teardown(){
    # remove symlinks before files
    local __DIR__="${__TEMPDIR__}/1234";
    local __FILE__="test.sh";
    local __DIR2__="${__TEMPDIR__}/12 34";
    local __FILE2__="te st.sh";

    [[ -e "${__DIR2__}" ]]                && rm -rf "${__DIR2__:?}";
    [[ -e "${__DIR__}/${__FILE2__}" ]]    && rm -f  "${__DIR__:?}/${__FILE2__}";
    [[ -e "${__DIR2__}/${__FILE__}" ]]    && rm -f  "${__DIR2__:?}/${__FILE__}";
    [[ -e "${__DIR2__}/${__FILE2__}" ]]   && rm -f  "${__DIR2__:?}/${__FILE2__}";
    [[ -e ${__TEMPDIR__}/"${__FILE__}" ]] && rm -f  "${__TEMPDIR__}/${__FILE__}";
    [[ -e ${__TEMPDIR__}/current ]]       && rm -rf "${__TEMPDIR__}/current";
    [[ -e ${__TEMPDIR__}/current/loop ]]  && rm -rf "${__TEMPDIR__}/current/loop";
    [[ -e "${__DIR__}" ]]                 && rm -rf "${__DIR__:?}";
    [[ -e "${__DIR__}/${__FILE__}" ]]     && rm -f  "${__DIR__:?}/${__FILE__}";
    
    rm_tempdir;
}

function setup(){
    set_tempdir;

    local __DIR__="${__TEMPDIR__}/1234";
    local __FILE__="test.sh";
    local __DIR2__="${__TEMPDIR__}/12 34";
    local __FILE2__="te st.sh";

    mkdir "${__DIR__}"
    touch "${__DIR__}/${__FILE__}"
    ln -s "${__DIR__}/${__FILE__}" "${__TEMPDIR__}"
    ln -s "${__DIR__}" "${__TEMPDIR__}/current"
    ln -s "${__DIR__}" "${__TEMPDIR__}/current/loop"
    mkdir "${__DIR2__}"
    ln -s "${__DIR__}/${__FILE__}" "${__DIR__}/${__FILE2__}"
    ln -s "${__DIR__}/${__FILE__}" "${__DIR2__}/${__FILE__}"
    ln -s "${__DIR__}/${__FILE__}" "${__DIR2__}/${__FILE2__}"
}

function test1(){
    echo 'Test 1: via dirname'
    cat <<- EOF >"${__TEMPDIR__}/1234/test.sh"
        echo \`dirname \$0\`
	EOF
}

function test2(){
    echo 'Test 2: via pwd'
    cat <<- EOF >"${__TEMPDIR__}/1234/test.sh"
        echo \$( cd "\$( dirname "\${BASH_SOURCE[0]}" )" && pwd )
	EOF
}

function test3(){
    echo 'Test 3: overcomplicated stackoverflow solution'
    cat <<- EOF >"${__TEMPDIR__}/1234/test.sh"
        __SOURCE__="\${BASH_SOURCE[0]}"
        while [ -h "\$__SOURCE__" ]; do
          __DIR__="\$( cd -P "\$( dirname "\$__SOURCE__" )" && pwd )"
          __SOURCE__="\$(readlink "\$__SOURCE__" 2> /dev/null)"
          [[ \$__SOURCE__ != /* ]] && __SOURCE__="\$__DIR__/\$__SOURCE__"
        done
        __DIR__="\$( cd -P "\$( dirname "\$__SOURCE__" )" && pwd )"
        echo \$__DIR__
	EOF
}

function test4(){
    echo 'Test 4: via readlink'
    cat <<- EOF >"${__TEMPDIR__}/1234/test.sh"
        echo \`dirname \$(readlink -f \$0 2> /dev/null)\`
	EOF
}

function test5(){
    echo 'Test 5: via readlink with space'
    cat <<- EOF >"${__TEMPDIR__}/1234/test.sh"
        echo \`dirname \$(readlink -f "\$0" 2> /dev/null)\`
	EOF
}

function test6(){
    echo 'Test 6: as Test 2 but with cd -P';
    cat <<- EOF >"${__TEMPDIR__}/1234/test.sh"
        echo \$( cd -P "\$( dirname "\${BASH_SOURCE[0]}" )" && pwd )
	EOF
}

function test7(){
    echo 'Test 7: via cd -P and pwd, testing for symlinked file first';
    cat <<- EOF >"${__TEMPDIR__}/1234/test.sh"
        __SOURCE__="\${BASH_SOURCE[0]}"
        while [[ -h "\${__SOURCE__}" ]]; do
            __SOURCE__=\$(find "\${__SOURCE__}" -type l -ls | sed -n 's/^.* -> \(.*\)/\1/p');
        done;

        echo \$(cd -P "\$( dirname "\${__SOURCE__}" )" && pwd)
	EOF
}

main(){

    local __TEMPDIR__="";

    echo;

    teardown; # sanity check (in case last run was interrupted)
    setup;

    if [[ -n "${1}" ]]; then
        "${1}" && testSuite;
    else
        test1 && testSuite;
        test2 && testSuite;
        test3 && testSuite;
        test4 && testSuite;
        test5 && testSuite;
        test6 && testSuite;
        test7 && testSuite;
    fi

    teardown;
}

main "$@";