Bash test: get the directory of a script

unit.sh

#!/bin/bash

tmp=$(python -c "import os, sys; print(os.path.realpath('/tmp'))")

function test {
    MESSAGE=$1
    RECEIVED=$2
    EXPECTED=$3

    if [ "$RECEIVED" = "$EXPECTED" ]; then
        echo -e "\033[32m✔︎ Tested $MESSAGE"
    else
        echo -e "\033[31m✘ Tested $MESSAGE"
        echo -e "  Received: $RECEIVED"
        echo -e "  Expected: $EXPECTED"
    fi
    echo -en "\033[0m"
}

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

function setup {
    DIR=$tmp/1234
    FILE=test.sh
    if [ -e $DIR ]; then rm -rf $DIR; fi; mkdir $DIR
    if [ -f $DIR/$FILE ]; then rm -rf $DIR/$FILE; fi; touch $DIR/$FILE
    if [ -f $tmp/$FILE ]; then rm $tmp/$FILE; fi; ln -s $DIR/$FILE $tmp
    if [ -f $tmp/current ]; then rm $tmp/current; fi; ln -s $DIR $tmp/current
    if [ -f $tmp/current/loop ]; then rm $tmp/current/loop; fi; ln -s $DIR $tmp/current/loop
    DIR2="$tmp/12 34"
    FILE2="te st.sh"
    if [ -e "$DIR2" ]; then rm -rf "$DIR2"; fi; mkdir "$DIR2"
    if [ -f "$DIR/$FILE2" ]; then rm -rf "$DIR/$FILE2"; fi; ln -s $DIR/$FILE "$DIR/$FILE2"
    if [ -f "$DIR2/$FILE" ]; then rm -rf "$DIR2/$FILE"; fi; ln -s $DIR/$FILE "$DIR2/$FILE"
    if [ -f "$DIR2/$FILE2" ]; then rm -rf "$DIR2/$FILE2"; fi; ln -s $DIR/$FILE "$DIR2/$FILE2"
}

function test1 {
    echo 'Test 1: via dirname'
    cat <<- 'EOF' >$tmp/1234/test.sh
	echo `dirname $0`
	EOF
    testSuite
}

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

function test3 {
    echo 'Test 3: overcomplicated stackoverflow solution'
    cat <<- 'EOF' >$tmp/1234/test.sh
	SOURCE="${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
    testSuite
}

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

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

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

function test7 {
    echo 'Test 7: via cd -P and pwd, testing for symlinked file first';
    cat <<- 'EOF' >$tmp/1234/test.sh
        __SOURCE__="${BASH_SOURCE[0]}"
        while [[ -h "${__SOURCE__}" ]]; do
            # shellcheck disable=SC1117
            __SOURCE__=$(find "${__SOURCE__}" -type l -ls | sed -n 's/^.* -> \(.*\)/\1/p');
        done;

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

function test8 {
    echo 'Test 8: ${0%/*}'
    cat <<- 'EOF' >$tmp/1234/test.sh
	echo "${0%/*}"
	EOF
    testSuite
}

function test9 {
    echo 'Test 9: python os.path functions'
    cat <<- 'EOF' >$tmp/1234/test.sh
	echo $(python -c "import os; print(os.path.dirname(os.path.realpath('${BASH_SOURCE[0]}')))")
	EOF
    testSuite
}

function test10 {
    echo 'Test 10: python3 pathlib functions'
    cat <<- 'EOF' >$tmp/1234/test.sh
	echo $(python3 -c "from pathlib import Path; print(Path('${BASH_SOURCE[0]}').resolve().parent)")
	EOF
    testSuite
}

function test11 {
    echo 'Test 11: oneliner from Binary Phile (https://stackoverflow.com/a/67149152/133106)'
    cat <<- 'EOF' >$tmp/1234/test.sh
	echo $(cd "$(dirname "$BASH_SOURCE")"; cd -P "$(dirname "$(readlink "$BASH_SOURCE" || echo .)")"; pwd)
	EOF
    testSuite
}


echo
setup
if [ "$1" != "" ]; then
    $1
else
    test1
    test2
    test3
    test4
    test5
    test6
    test7
    test8
    test9
    test10
    test11
fi