Issue #3390941: Investigate adding a Mutation testing stage

.gitlab-ci.yml

@@ -32,7 +32,7 @@ variables:
     value: "$CORE_PHP_MAX"
   # Collect code coverage data.
   _PHPUNIT_EXTRA:
-    value: --coverage-cobertura $CI_PROJECT_DIR/coverage.xml --coverage-filter $CI_PROJECT_DIR/$_WEB_ROOT/modules/custom/ --coverage-text --colors=never
+    value: --coverage-xml=$CI_PROJECT_DIR/build/coverage/coverage-xml --coverage-cobertura $CI_PROJECT_DIR/coverage.xml --coverage-filter $CI_PROJECT_DIR/$_WEB_ROOT/modules/custom/ --coverage-text --colors=never
   # Generate a new phpstan baseline.
   GENERATE_PHPSTAN_BASELINE:
     value: "0"
@@ -112,7 +112,7 @@ phpstan-new-baseline:
 #   * Enable PCOV Coverage Reporting.
 #   * Collect code coverage data.
 ################
-phpunit:
+.local-phpunit-base:
   extends: .phpunit-base
   services:
     # Include the normal containers.
@@ -132,6 +132,8 @@ phpunit:
     # write the aliases to the hosts file.
     - echo "$localstack_ipaddr s3.localhost.localstack.cloud s3fs-test-bucket.s3.localhost.localstack.cloud" >> /etc/hosts
 
+phpunit:
+  extends: .local-phpunit-base
   after_script:
     # Ensure paths for coverage are git-relative.
     - sed -i "s#<source>$CI_PROJECT_DIR/web/modules/custom/$CI_PROJECT_NAME#<source>$CI_PROJECT_DIR#" coverage.xml
@@ -147,3 +149,45 @@ phpunit:
       - apache.access.log.txt
       - $BROWSERTEST_OUTPUT_DIRECTORY
       - coverage.xml
+      - build
+
+################
+# Mutation tests.
+################
+mutation:
+  extends: .local-phpunit-base
+  needs:
+    - job: composer
+      optional: false
+    - job: phpunit
+      optional: false
+  before_script:
+    # We don't need PCOV as we use existing coverage report.
+    # GitLab doesn't support aliases when setting up the container.
+    # Get the IP for the localstack container.
+    - localstack_ipaddr=$(getent hosts localstack-localstack | cut -d " " -f 1)
+    # write the aliases to the hosts file.
+    - echo "$localstack_ipaddr s3.localhost.localstack.cloud s3fs-test-bucket.s3.localhost.localstack.cloud" >> /etc/hosts
+  script:
+    # Infection requres the junit file in the coverage folder.
+    - ln -s $CI_PROJECT_DIR/junit.xml $CI_PROJECT_DIR/build/coverage/junit.xml
+    # Setup the container for testing.
+    - !reference [.setup-webserver]
+    - !reference [.simpletest-db]
+    - !reference [.show-environment-variables]
+    # Provide some context on the test run.
+    - vendor/bin/drush status
+    # If $CI_MERGE_REQUEST_DIFF_BASE_SHA is empty run over all files
+    # otherwise run over only altered lines.
+    - >
+      if [ -z $CI_MERGE_REQUEST_DIFF_BASE_SHA ]; then
+       cd $CI_PROJECT_DIR/web/modules/custom/$CI_PROJECT_NAME; sudo -u www-data -E $CI_PROJECT_DIR/vendor/bin/infection --configuration=$CI_PROJECT_DIR/web/modules/custom/$CI_PROJECT_NAME/infection.json5.dist --skip-initial-tests --only-covering-test-cases --threads=6 --coverage=$CI_PROJECT_DIR/build/coverage --filter=$CI_PROJECT_DIR/web/modules/custom/$CI_PROJECT_NAME --logger-gitlab="$CI_PROJECT_DIR/infection-gitlab.json" --logger-html="$CI_PROJECT_DIR/mutation-report.html"
+      else
+       cd $CI_PROJECT_DIR/web/modules/custom/$CI_PROJECT_NAME; sudo -u www-data -E $CI_PROJECT_DIR/vendor/bin/infection --git-diff-base=$CI_MERGE_REQUEST_DIFF_BASE_SHA --git-diff-lines --configuration=$CI_PROJECT_DIR/web/modules/custom/$CI_PROJECT_NAME/infection.json5.dist --skip-initial-tests --only-covering-test-cases --threads=6 --coverage=$CI_PROJECT_DIR/build/coverage --logger-gitlab="$CI_PROJECT_DIR/infection-gitlab.json" --logger-html="$CI_PROJECT_DIR/mutation-report.html"
+      fi
+  artifacts:
+    reports:
+      codequality: infection-gitlab.json
+    paths:
+      - infection-gitlab.json
+      - mutation-report.html