Build a CSV matrix showing versions of Asciidoctor that produce identical output

Build.sh

#!/bin/bash

#
# Usage:
#    sudo Build [test-file.adoc] > result.csv
#

set -e

TESTFILE="${1:-test-file.adoc}"    # the test file
DIFF="${DIFF:-diff}"               # the diff tool
BASEIMAGE="${BASEIMAGE:-ruby:alpine3.12}"

[ -r "${TESTFILE}" ] || ( echo Can\'t read file: ${TESTFILE} >&2; exit 1 )
RESULTS=()

#
# Collect the version tags from the remote repository
#
echo "Collecting tags" >&2
VERSIONS=( $(
  git ls-remote --tags https://github.com/asciidoctor/asciidoctor |
    awk -F/ '/v[0-9]+\.[0-9]+\.[0-9]+$/ { print $3 }' | sort -V
))

#
# Create a new docker image for each Asciidoctor version
# and start a conversion in a corresponding container
#
for VERSION in "${VERSIONS[@]}"; do
  TAG="asciidoctor:${VERSION}"

  echo "Building ${TAG}" >&2
  docker build --quiet --tag "${TAG}" - > /dev/null <<- EOF
    FROM ${BASEIMAGE}

    RUN gem install asciidoctor -"${VERSION}"

    CMD asciidoctor -b docbook -
EOF

  DESTFILE="${TESTFILE%.*}-${TAG}"
  RESULTS+=( "${DESTFILE}" )
  docker run -i --rm "${TAG}" < "${TESTFILE}" > "${DESTFILE}" || rm -f "${DESTFILE}" &
done

echo Waiting for tests completion >&2
wait
echo Done >&2

#
# Print the results as a CSV table
#

# Header lines
echo "${TESTFILE} (${BASEIMAGE})"
for A in "${RESULTS[@]}"; do
  echo -n ", ${A##*:}"
done
echo

#
# Compare all results 2 by 2
#
# Obviously the matrix is symetric so we could optimize that...
#
for A in "${RESULTS[@]}"; do
  echo -n "${A##*:}"
  for B in "${RESULTS[@]}"; do
    if [ -r "${A}" -a -r "${B}" ]; then
      if diff "${A}" "${B}" > /dev/null 2>&1 ; then
        echo -n ", M"
      else
        echo -n ", x"
      fi
    else
      echo -n ", -"
    fi
  done
  echo
done