tests(`pytest.sh`): Update Syntax

- Added clarification comment of the DIR command
- Quoted `ARGS` usage required wrapping `ARGS` assignment in an array to properly expand. This wasn't broken before, but is required change to keep ShellCheck  lint happy.
- Quote wrapped `DIR` usage, the volume target had an extra `/` before the `DIR` which seems unnecessary as `pwd` should return absolute path.
- Expanded `docker run` options to long-form.

test/pytest.sh

@@ -8,17 +8,18 @@
 #                                                                             #
 ###############################################################################
 
+# Returns the absolute directory path to this script
 DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
-ARGS="$@"
+ARGS=("$@")
 
 # check requirements
 echo "> Building nginx-proxy-tester image..."
-docker build -t nginx-proxy-tester -f $DIR/requirements/Dockerfile-nginx-proxy-tester $DIR/requirements
+docker build -t nginx-proxy-tester -f "${DIR}/requirements/Dockerfile-nginx-proxy-tester" "${DIR}/requirements"
 
 # run the nginx-proxy-tester container setting the correct value for the working dir in order for 
 # docker-compose to work properly when run from within that container.
 exec docker run --rm -it \
-	-v ${DIR}:/${DIR} \
-	-w ${DIR} \
-	-v /var/run/docker.sock:/var/run/docker.sock \
-	nginx-proxy-tester ${ARGS}
+--volume /var/run/docker.sock:/var/run/docker.sock \
+--volume "${DIR}:${DIR}" \
+--workdir "${DIR}" \
+nginx-proxy-tester "${ARGS[@]}"