Publish PHPUnit code coverage result in Pipeline Azure

PHPUnit 9.4 added support for Cobertura coverage output. However the default Ubuntu build agents that Azure Pipelines provides atm. only support phpunit 8.5. But you can get coverage reports by running phpunit 9.4+ inside a docker container instead. Here is a snippet of my current azure build pipeline that does that:

trigger:
- master

pool:
  vmImage: ubuntu-latest

variables:
  phpVersion: 7.4
  phpunitImage: jitesoft/phpunit:7.4-9

steps:
- script: |
    sudo update-alternatives --set php /usr/bin/php$(phpVersion)
    sudo update-alternatives --set phar /usr/bin/phar$(phpVersion)
    sudo update-alternatives --set phpdbg /usr/bin/phpdbg$(phpVersion)
    sudo update-alternatives --set php-cgi /usr/bin/php-cgi$(phpVersion)
    sudo update-alternatives --set phar.phar /usr/bin/phar.phar$(phpVersion)
    php -version
  displayName: 'Use PHP version $(phpVersion)'

# Do a composer install to get an autoloader that phpunit can use
- script: composer install --no-interaction --prefer-dist
  displayName: 'composer install'

# Run the test using the jitesoft phpunit docker image to get support
# for phpunit 9+ and that way cobertura reports for code coverage.
- script: |
    docker run --rm -v $(pwd):/app ${{ variables.phpunitImage }} phpunit --log-junit .junit/TEST-phpunit-junit.xml --coverage-cobertura=.coverage/COVERAGE-phpunit-cobertura.xml
  displayName: 'Run tests with phpunit docker container'

- task: PublishTestResults@2
  displayName: 'Publish test report'
  condition: always()
  inputs:
    testResultsFormat: 'JUnit'
    testResultsFiles: '**/TEST-phpunit-*.xml'
    searchFolder: '$(System.DefaultWorkingDirectory)/.junit'
    failTaskOnFailedTests: true

- task: PublishCodeCoverageResults@1
  displayName: 'Publish coverage report'
  condition: always()
  inputs:
    codeCoverageTool: 'Cobertura'
    summaryFileLocation: '$(System.DefaultWorkingDirectory)/.coverage/COVERAGE-phpunit-*.xml'
    pathToSources: '$(System.DefaultWorkingDirectory)/src'
    failIfCoverageEmpty: true

note the always() condition in the Publish* tasks. This is needed because if a test fails, then the docker run step will fail with a bash exit code 1, which in turn would prevent the report publishing unless those steps are forced. There might be a way to handle the exit code cleaner, but I haven't figured it out yet.

ps. ideally you'd do some caching as well so the docker image is not always downloaded, but I skipped that part to keep the example focused on the actual running of unit tests and coverage reports.

As of this time, however, publishing PHPUnit code coverage result in Pipeline is not supported.