diff --git a/.github/workflows/database-tests.yml b/.github/workflows/database-tests.yml
new file mode 100644
index 0000000000000..37dddcccc3062
--- /dev/null
+++ b/.github/workflows/database-tests.yml
@@ -0,0 +1,345 @@
+name: Database Tests
+
+on:
+  push:
+    branches:
+      - master
+      - trunk
+      - '3.[7-9]'
+      - '[4-9].[0-9]'
+    tags:
+      - '3.[7-9]*'
+      - '[4-9].[0-9]*'
+  pull_request:
+    branches:
+      - master
+      - trunk
+      - '3.[7-9]'
+      - '[4-9].[0-9]'
+  workflow_dispatch:
+  # Once weekly On Sundays at 00:00 UTC.
+  schedule:
+    - cron: '0 0 * * 0'
+
+# Cancels all previous workflow runs for pull requests that have not completed.
+concurrency:
+  # The concurrency group contains the workflow name and the branch name for pull requests
+  # or the commit hash for any other events.
+  group: ${{ github.workflow }}-${{ github.event_name == 'pull_request' && github.head_ref || github.sha }}
+  cancel-in-progress: true
+
+env:
+  PUPPETEER_SKIP_CHROMIUM_DOWNLOAD: ${{ true }}
+  COMPOSER_INSTALL: ${{ false }}
+  # Controls which NPM script to use for running PHPUnit tests. Options ar `php` and `php-composer`.
+  PHPUNIT_SCRIPT: php
+  LOCAL_PHP_MEMCACHED: ${{ false }}
+
+jobs:
+  # Runs the PHPUnit tests for WordPress on MySQL.
+  #
+  # Performs the following steps:
+  # - Set environment variables.
+  # - Sets up the environment variables needed for testing with memcached (if desired).
+  # - Installs NodeJS 14.
+  # - Sets up caching for NPM.
+  # - Installs NPM dependencies
+  # - Configures caching for Composer.
+  # - Installs Composer dependencies (if desired).
+  # - Logs Docker debug information (about both the Docker installation within the runner).
+  # - Starts the WordPress Docker container.
+  # - Starts the memcached server after the Docker network has been created (if desired).
+  # - Logs WordPress Docker container debug information.
+  # - Logs debug general information.
+  # - Logs the running Docker containers.
+  # - Logs debug information about what's installed within the WordPress Docker containers.
+  # - Install WordPress within the Docker container.
+  # - Run the PHPUnit tests.
+  # - Checks out the WordPress Test reporter repository.
+  # - Reconnect the directory to the Git repository.
+  # - Submit the test results to the WordPress.org host test results.
+  # - todo: Configure Slack notifications for failing tests.
+  test-mysql:
+    name: ${{ matrix.php }}${{ matrix.multisite && ' multisite' || '' }}${{ matrix.memcached && ' with memcached' || '' }} with MySQL ${{ matrix.mysql }} on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    if: ${{ github.repository == 'WordPress/wordpress-develop' || github.event_name == 'pull_request' }}
+    strategy:
+      fail-fast: false
+      matrix:
+        php: [ '5.6.20', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0' ]
+        mysql: [ '5.6', '5.7', '8.0' ]
+        os: [ ubuntu-latest ]
+        memcached: [ false ]
+        multisite: [ false, true ]
+        include:
+          # Include jobs for PHP 7.4 with memcached.
+          - php: '7.4'
+            mysql: '8.0'
+            os: ubuntu-latest
+            memcached: true
+            multisite: false
+          - php: '7.4'
+            mysql: '8.0'
+            os: ubuntu-latest
+            memcached: true
+            multisite: true
+        exclude:
+          # Exclude jobs for PHP 5.6/MySQL 8.0.
+          - php: '5.6.20'
+            mysql: '8.0'
+            os: ubuntu-latest
+            multisite: false
+          - php: '5.6.20'
+            mysql: '8.0'
+            os: ubuntu-latest
+            multisite: true
+
+    env:
+      LOCAL_PHP: ${{ matrix.php }}-fpm
+      LOCAL_PHP_MEMCACHED: ${{ matrix.memcached }}
+      LOCAL_DB_TYPE: mysql
+      LOCAL_DB_VERSION: ${{ matrix.mysql }}
+      PHPUNIT_CONFIG: ${{ matrix.multisite && 'tests/phpunit/multisite.xml' || 'phpunit.xml.dist' }}
+
+    steps:
+      - name: Configure environment variables
+        run: |
+          echo "PHP_FPM_UID=$(id -u)" >> $GITHUB_ENV
+          echo "PHP_FPM_GID=$(id -g)" >> $GITHUB_ENV
+
+      - name: Checkout repository
+        uses: actions/checkout@5a4ac9002d0be2fb38bd78e4b4dbde5606d7042f # v2.3.4
+
+      - name: Install NodeJS
+        uses: actions/setup-node@46071b5c7a2e0c34e49c3cb8a0e792e86e18d5ea # v2.1.5
+        with:
+          node-version: 14
+
+      - name: Use cached Node modules
+        uses: actions/cache@26968a09c0ea4f3e233fdddbafd1166051a095f6 # v2.1.4
+        env:
+          cache-name: cache-node-modules
+        with:
+          # npm cache files are stored in `~/.npm` on Linux/macOS
+          path: ~/.npm
+          key: ${{ runner.os }}-npm-${{ hashFiles('**/package-lock.json') }}
+
+      - name: Install Dependencies
+        run: npm ci
+
+      - name: Get composer cache directory
+        id: composer-cache
+        if: ${{ env.COMPOSER_INSTALL == true || env.LOCAL_PHP == '8.0-fpm' }}
+        run: echo "::set-output name=dir::$(composer config cache-files-dir)"
+
+      - name: Cache Composer dependencies
+        if: ${{ env.COMPOSER_INSTALL == true || env.LOCAL_PHP == '8.0-fpm' }}
+        uses: actions/cache@26968a09c0ea4f3e233fdddbafd1166051a095f6 # v2.1.4
+        env:
+          cache-name: cache-composer-dependencies
+        with:
+          path: ${{ steps.composer-cache.outputs.dir }}
+          key: ${{ runner.os }}-php-${{ matrix.php }}-composer-${{ hashFiles('**/composer.lock') }}
+
+      - name: Install Composer dependencies
+        if: ${{ env.COMPOSER_INSTALL == true || env.LOCAL_PHP == '8.0-fpm' }}
+        run: |
+          docker-compose run --rm php composer --version
+
+          # The PHPUnit 7.x phar is not compatible with PHP 8 and won't be updated,
+          # as PHPUnit 7 is no longer supported. The Composer-installed PHPUnit should be
+          # used for PHP 8 testing instead.
+          if [ ${{ env.LOCAL_PHP }} == '8.0-fpm' ]; then
+            docker-compose run --rm php composer install --ignore-platform-reqs
+            echo "PHPUNIT_SCRIPT=php-composer" >> $GITHUB_ENV
+          else
+            docker-compose run --rm php composer install
+          fi
+
+      - name: Docker debug information
+        run: |
+          docker -v
+          docker-compose -v
+
+      - name: Start Docker environment
+        run: |
+          npm run env:start
+
+      # The memcached server needs to start after the Docker network has been set up with `npm run env:start`.
+      - name: Start the Memcached server.
+        if: ${{ matrix.memcached }}
+        run: |
+          cp tests/phpunit/includes/object-cache.php src/wp-content/object-cache.php
+          docker run --name memcached --net $(basename "$PWD")_wpdevnet -d memcached
+
+      - name: General debug information
+        run: |
+          npm --version
+          node --version
+          curl --version
+          git --version
+          svn --version
+
+      - name: Log running Docker containers
+        run: docker ps -a
+
+      - name: WordPress Docker container debug information
+        run: |
+          docker-compose run --rm mysql mysql --version
+          docker-compose run --rm php php --version
+          docker-compose run --rm php php -m
+          docker-compose run --rm php php -i
+          docker-compose run --rm php locale -a
+
+      - name: Install WordPress
+        run: npm run env:install
+
+      - name: Run database tests
+        run: npm run test:${{ env.PHPUNIT_SCRIPT }} -- --verbose -c ${{ env.PHPUNIT_CONFIG }} --group wpdb,dbDelta,query,compat
+
+  #
+  # Performs the following steps:
+  # - Set environment variables.
+  # - Sets up the environment variables needed for testing with memcached (if desired).
+  # - Installs NodeJS 14.
+  # - Sets up caching for NPM.
+  # - Installs NPM dependencies
+  # - Configures caching for Composer.
+  # - Installs Composer dependencies (if desired).
+  # - Logs Docker debug information (about both the Docker installation within the runner).
+  # - Starts the WordPress Docker container.
+  # - Starts the memcached server after the Docker network has been created (if desired).
+  # - Logs WordPress Docker container debug information.
+  # - Logs debug general information.
+  # - Logs the running Docker containers.
+  # - Logs debug information about what's installed within the WordPress Docker containers.
+  # - Install WordPress within the Docker container.
+  # - Run the PHPUnit tests.
+  # - Checks out the WordPress Test reporter repository.
+  # - Reconnect the directory to the Git repository.
+  # - Submit the test results to the WordPress.org host test results.
+  # - todo: Configure Slack notifications for failing tests.
+  test-mariadb:
+    name: ${{ matrix.php }}${{ matrix.multisite && ' multisite' || '' }}${{ matrix.memcached && ' with memcached' || '' }} with MariaDB ${{ matrix.mariadb }} on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    if: ${{ github.repository == 'WordPress/wordpress-develop' || github.event_name == 'pull_request' }}
+    strategy:
+      fail-fast: false
+      matrix:
+        php: [ '5.6.20', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0' ]
+        mariadb: [ '10.1', '10.2', '10.3', '10.4', '10.5', '10.6' ]
+        os: [ ubuntu-latest ]
+        memcached: [ false ]
+        multisite: [ false, true ]
+        include:
+          # Include jobs for PHP 7.4 with memcached.
+          - php: '7.4'
+            os: ubuntu-latest
+            memcached: true
+            multisite: false
+          - php: '7.4'
+            os: ubuntu-latest
+            memcached: true
+            multisite: true
+    env:
+      LOCAL_PHP: ${{ matrix.php }}-fpm
+      LOCAL_PHP_MEMCACHED: ${{ matrix.memcached }}
+      LOCAL_DB_TYPE: mariadb
+      LOCAL_DB_VERSION: ${{ matrix.mariadb }}
+      PHPUNIT_CONFIG: ${{ matrix.multisite && 'tests/phpunit/multisite.xml' || 'phpunit.xml.dist' }}
+
+    steps:
+      - name: Configure environment variables
+        run: |
+          echo "PHP_FPM_UID=$(id -u)" >> $GITHUB_ENV
+          echo "PHP_FPM_GID=$(id -g)" >> $GITHUB_ENV
+
+      - name: Checkout repository
+        uses: actions/checkout@5a4ac9002d0be2fb38bd78e4b4dbde5606d7042f # v2.3.4
+
+      - name: Install NodeJS
+        uses: actions/setup-node@46071b5c7a2e0c34e49c3cb8a0e792e86e18d5ea # v2.1.5
+        with:
+          node-version: 14
+
+      - name: Use cached Node modules
+        uses: actions/cache@26968a09c0ea4f3e233fdddbafd1166051a095f6 # v2.1.4
+        env:
+          cache-name: cache-node-modules
+        with:
+          # npm cache files are stored in `~/.npm` on Linux/macOS
+          path: ~/.npm
+          key: ${{ runner.os }}-npm-${{ hashFiles('**/package-lock.json') }}
+
+      - name: Install Dependencies
+        run: npm ci
+
+      - name: Get composer cache directory
+        id: composer-cache
+        if: ${{ env.COMPOSER_INSTALL == true || env.LOCAL_PHP == '8.0-fpm' }}
+        run: echo "::set-output name=dir::$(composer config cache-files-dir)"
+
+      - name: Cache Composer dependencies
+        if: ${{ env.COMPOSER_INSTALL == true || env.LOCAL_PHP == '8.0-fpm' }}
+        uses: actions/cache@26968a09c0ea4f3e233fdddbafd1166051a095f6 # v2.1.4
+        env:
+          cache-name: cache-composer-dependencies
+        with:
+          path: ${{ steps.composer-cache.outputs.dir }}
+          key: ${{ runner.os }}-php-${{ matrix.php }}-composer-${{ hashFiles('**/composer.lock') }}
+
+      - name: Install Composer dependencies
+        if: ${{ env.COMPOSER_INSTALL == true || env.LOCAL_PHP == '8.0-fpm' }}
+        run: |
+          docker-compose run --rm php composer --version
+
+          # The PHPUnit 7.x phar is not compatible with PHP 8 and won't be updated,
+          # as PHPUnit 7 is no longer supported. The Composer-installed PHPUnit should be
+          # used for PHP 8 testing instead.
+          if [ ${{ env.LOCAL_PHP }} == '8.0-fpm' ]; then
+            docker-compose run --rm php composer install --ignore-platform-reqs
+            echo "PHPUNIT_SCRIPT=php-composer" >> $GITHUB_ENV
+          else
+            docker-compose run --rm php composer install
+          fi
+
+      - name: Docker debug information
+        run: |
+          docker -v
+          docker-compose -v
+
+      - name: Start Docker environment
+        run: |
+          npm run env:start
+
+      # The memcached server needs to start after the Docker network has been set up with `npm run env:start`.
+      - name: Start the Memcached server.
+        if: ${{ matrix.memcached }}
+        run: |
+          cp tests/phpunit/includes/object-cache.php src/wp-content/object-cache.php
+          docker run --name memcached --net $(basename "$PWD")_wpdevnet -d memcached
+
+      - name: General debug information
+        run: |
+          npm --version
+          node --version
+          curl --version
+          git --version
+          svn --version
+
+      - name: Log running Docker containers
+        run: docker ps -a
+
+      - name: WordPress Docker container debug information
+        run: |
+          docker-compose run --rm mysql mysql --version
+          docker-compose run --rm php php --version
+          docker-compose run --rm php php -m
+          docker-compose run --rm php php -i
+          docker-compose run --rm php locale -a
+
+      - name: Install WordPress
+        run: npm run env:install
+
+      - name: Run database tests
+        run: npm run test:${{ env.PHPUNIT_SCRIPT }} -- --verbose -c ${{ env.PHPUNIT_CONFIG }} --group wpdb,dbDelta,query,compat
diff --git a/.github/workflows/expanded-db-testing.yml b/.github/workflows/expanded-db-testing.yml
new file mode 100644
index 0000000000000..ca78b93a513ef
--- /dev/null
+++ b/.github/workflows/expanded-db-testing.yml
@@ -0,0 +1,374 @@
+name: Expanded Database Testing
+
+on:
+  pull_request:
+  # Once weekly On Sundays at 00:00 UTC.
+  schedule:
+    - cron: '0 0 * * 0'
+
+env:
+  LOCAL_DIR: build
+  PUPPETEER_SKIP_CHROMIUM_DOWNLOAD: ${{ true }}
+  COMPOSER_INSTALL: ${{ false }}
+  # Controls which NPM script to use for running PHPUnit tests. Options ar `php` and `php-composer`.
+  PHPUNIT_SCRIPT: php
+  LOCAL_PHP_MEMCACHED: ${{ false }}
+
+jobs:
+  # Sets up WordPress for testing or development use.
+  #
+  # Performs the following steps:
+  # - Cancels all previous workflow runs for pull requests that have not completed.
+  # - Checks out the repository.
+  # - Checks out the WordPress Importer plugin (needed for the Core PHPUnit tests).
+  # - Logs debug information about the runner container.
+  # - Installs NodeJS 14.
+  # - Sets up caching for NPM.
+  # _ Installs NPM dependencies using install-changed to hash the `package.json` file.
+  # - Builds WordPress to run from the `build` directory.
+  # - Creates a ZIP file of compiled WordPress.
+  # - Uploads ZIP file as an artifact.
+  setup-wordpress:
+    name: Setup WordPress
+    runs-on: ubuntu-latest
+    if: ${{ github.repository == 'WordPress/wordpress-develop' || github.event_name == 'pull_request' }}
+
+    steps:
+      - name: Cancel previous runs of this workflow (pull requests only)
+        if: ${{ github.event_name == 'pull_request' }}
+        uses: styfle/cancel-workflow-action@0.5.0
+        with:
+          access_token: ${{ github.token }}
+
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Checkout the WordPress Importer plugin
+        run: svn checkout -r 2387243 https://plugins.svn.wordpress.org/wordpress-importer/trunk/ tests/phpunit/data/plugins/wordpress-importer
+
+      - name: Log debug information
+        run: |
+          echo "$GITHUB_REF"
+          echo "$GITHUB_EVENT_NAME"
+          npm --version
+          node --version
+          curl --version
+          git --version
+          svn --version
+          php --version
+          php -i
+          locale -a
+
+      - name: Install NodeJS
+        uses: actions/setup-node@v1
+        with:
+          node-version: 14
+
+      - name: Cache NodeJS modules
+        uses: actions/cache@v2
+        env:
+          cache-name: cache-node-modules
+        with:
+          # npm cache files are stored in `~/.npm` on Linux/macOS
+          path: ~/.npm
+          key: ${{ runner.os }}-npm-${{ hashFiles('**/package-lock.json') }}
+          restore-keys: |
+            ${{ runner.os }}-npm-
+
+      - name: Install Dependencies
+        run: npx install-changed --install-command="npm ci"
+
+      - name: Build WordPress
+        run: npm run build
+
+      - name: Create ZIP artifact
+        uses: thedoctor0/zip-release@0.4.1
+        with:
+          filename: built-wp-${{ github.sha }}.zip
+          exclusions: '*.git* /*node_modules/* packagehash.txt'
+
+      - name: Upload build artifact
+        uses: actions/upload-artifact@v2
+        with:
+          name: built-wp-${{ github.sha }}
+          path: built-wp-${{ github.sha }}.zip
+          if-no-files-found: error
+
+  # Runs the PHPUnit tests for WordPress.
+  #
+  # Performs the following steps:
+  # - Set environment variables.
+  # - Downloads the built WordPress artifact from the previous job.
+  # - Unzips the artifact.
+  # - Installs NodeJS 14.
+  # - Sets up caching for NPM.
+  # _ Installs NPM dependencies using install-changed to hash the `package.json` file.
+  # - Configures caching for Composer.
+  # _ Installs Composer dependencies (if desired).
+  # - Logs Docker debug information (about both the Docker installation within the runner).
+  # - Starts the WordPress Docker container.
+  # - Logs WordPress Docker container debug information.
+  # - Logs debug general information.
+  # - Logs the running Docker containers.
+  # - Logs debug information about what's installed within the WordPress Docker containers.
+  # - Install WordPress within the Docker container.
+  # - Run the PHPUnit tests.
+  # - Checks out the WordPress Test reporter repository.
+  # - Reconnect the directory to the Git repository.
+  # - Submit the test results to the WordPress.org host test results.
+  # - todo: Configure Slack notifications for failing tests.
+  test-mysql:
+    name: PHP ${{ matrix.php }} with MySQL ${{ matrix.db_version }}
+    needs: setup-wordpress
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        php: [ '8.0', '7.4', '7.3', '7.2', '7.1', '7.0', '5.6.20' ]
+        os: [ ubuntu-latest ]
+        db_type: [ 'mysql' ]
+        db_version: [ '5.6', '5.7', '8.0' ]
+    env:
+      LOCAL_PHP: ${{ matrix.php }}-fpm
+      LOCAL_DB_TYPE: ${{ matrix.db_type }}
+      LOCAL_DB_VERSION: ${{ matrix.db_version }}
+
+    steps:
+      - name: Configure environment variables
+        run: |
+          echo "PHP_FPM_UID=$(id -u)" >> $GITHUB_ENV
+          echo "PHP_FPM_GID=$(id -g)" >> $GITHUB_ENV
+
+      - name: Download the built WordPress artifact
+        uses: actions/download-artifact@v2
+        with:
+          name: built-wp-${{ github.sha }}
+
+      - name: Unzip built artifact
+        run: unzip built-wp-${{ github.sha }}.zip
+
+      - name: Install NodeJS
+        uses: actions/setup-node@v1
+        with:
+          node-version: 14
+
+      - name: Use cached Node modules
+        uses: actions/cache@v2
+        env:
+          cache-name: cache-node-modules
+        with:
+          # npm cache files are stored in `~/.npm` on Linux/macOS
+          path: ~/.npm
+          key: ${{ runner.os }}-npm-${{ hashFiles('**/package-lock.json') }}
+          restore-keys: |
+            ${{ runner.os }}-npm-
+
+      - name: Install Dependencies
+        run: npx install-changed --install-command="npm ci"
+
+      - name: Get composer cache directory
+        id: composer-cache
+        if: ${{ env.COMPOSER_INSTALL == true || env.LOCAL_PHP == '8.0-fpm' }}
+        run: echo "::set-output name=dir::$(composer config cache-files-dir)"
+
+      - name: Cache Composer dependencies
+        if: ${{ env.COMPOSER_INSTALL == true || env.LOCAL_PHP == '8.0-fpm' }}
+        uses: actions/cache@v2
+        env:
+          cache-name: cache-composer-dependencies
+        with:
+          path: ${{ steps.composer-cache.outputs.dir }}
+          key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-composer-
+
+      - name: Install Composer dependencies
+        if: ${{ env.COMPOSER_INSTALL == true || env.LOCAL_PHP == '8.0-fpm' }}
+        run: |
+          docker-compose run --rm php composer --version
+
+          # The PHPUnit 7.x phar is not compatible with PHP 8 and won't be updated,
+          # as PHPUnit 7 is no longer supported. The Composer-installed PHPUnit should be
+          # used for PHP 8 testing instead.
+          if [ ${{ env.LOCAL_PHP }} == '8.0-fpm' ]; then
+            docker-compose run --rm php composer install --ignore-platform-reqs
+            echo "PHPUNIT_SCRIPT=php-composer" >> $GITHUB_ENV
+          else
+            docker-compose run --rm php composer install
+          fi
+
+      - name: Docker debug information
+        run: |
+          docker -v
+          docker-compose -v
+
+      - name: Start Docker environment
+        run: |
+          npm run env:start
+
+      - name: General debug information
+        run: |
+          npm --version
+          node --version
+          curl --version
+          git --version
+          svn --version
+
+      - name: Log running Docker containers
+        run: docker ps -a
+
+      - name: WordPress Docker container debug information
+        run: |
+          docker-compose run --rm mysql mysql --version
+          docker-compose run --rm php php --version
+          docker-compose run --rm php php -m
+          docker-compose run --rm php php -i
+          docker-compose run --rm php locale -a
+
+      - name: Install WordPress
+        run: npm run env:install
+
+      - name: Run PHPUnit tests
+        run: npm run test:${{ env.PHPUNIT_SCRIPT }} -- --verbose -c phpunit.xml.dist
+
+      - name: Run tests as a multisite install
+        run: npm run test:${{ env.PHPUNIT_SCRIPT }} -- --verbose -c tests/phpunit/multisite.xml
+
+
+  # Runs the PHPUnit tests for WordPress.
+  #
+  # Performs the following steps:
+  # - Set environment variables.
+  # - Downloads the built WordPress artifact from the previous job.
+  # - Unzips the artifact.
+  # - Installs NodeJS 14.
+  # - Sets up caching for NPM.
+  # _ Installs NPM dependencies using install-changed to hash the `package.json` file.
+  # - Configures caching for Composer.
+  # _ Installs Composer dependencies (if desired).
+  # - Logs Docker debug information (about both the Docker installation within the runner).
+  # - Starts the WordPress Docker container.
+  # - Logs WordPress Docker container debug information.
+  # - Logs debug general information.
+  # - Logs the running Docker containers.
+  # - Logs debug information about what's installed within the WordPress Docker containers.
+  # - Install WordPress within the Docker container.
+  # - Run the PHPUnit tests.
+  # - Checks out the WordPress Test reporter repository.
+  # - Reconnect the directory to the Git repository.
+  # - Submit the test results to the WordPress.org host test results.
+  # - todo: Configure Slack notifications for failing tests.
+  test-mariadb:
+    name: PHP ${{ matrix.php }} with MariaDB ${{ matrix.db_version }}
+    needs: setup-wordpress
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        php: [ '8.0', '7.4', '7.3', '7.2', '7.1', '7.0', '5.6.20' ]
+        os: [ ubuntu-latest ]
+        db_type: [ 'mysql' ]
+        db_version: [ '10.5', '10.4', '10.3', '10.2', '10.1' ]
+    env:
+      LOCAL_PHP: ${{ matrix.php }}-fpm
+      LOCAL_DB_TYPE: ${{ matrix.db_type }}
+      LOCAL_DB_VERSION: ${{ matrix.db_version }}
+
+    steps:
+      - name: Configure environment variables
+        run: |
+          echo "PHP_FPM_UID=$(id -u)" >> $GITHUB_ENV
+          echo "PHP_FPM_GID=$(id -g)" >> $GITHUB_ENV
+
+      - name: Download the built WordPress artifact
+        uses: actions/download-artifact@v2
+        with:
+          name: built-wp-${{ github.sha }}
+
+      - name: Unzip built artifact
+        run: unzip built-wp-${{ github.sha }}.zip
+
+      - name: Install NodeJS
+        uses: actions/setup-node@v1
+        with:
+          node-version: 14
+
+      - name: Use cached Node modules
+        uses: actions/cache@v2
+        env:
+          cache-name: cache-node-modules
+        with:
+          # npm cache files are stored in `~/.npm` on Linux/macOS
+          path: ~/.npm
+          key: ${{ runner.os }}-npm-${{ hashFiles('**/package-lock.json') }}
+          restore-keys: |
+            ${{ runner.os }}-npm-
+
+      - name: Install Dependencies
+        run: npx install-changed --install-command="npm ci"
+
+      - name: Get composer cache directory
+        id: composer-cache
+        if: ${{ env.COMPOSER_INSTALL == true || env.LOCAL_PHP == '8.0-fpm' }}
+        run: echo "::set-output name=dir::$(composer config cache-files-dir)"
+
+      - name: Cache Composer dependencies
+        if: ${{ env.COMPOSER_INSTALL == true || env.LOCAL_PHP == '8.0-fpm' }}
+        uses: actions/cache@v2
+        env:
+          cache-name: cache-composer-dependencies
+        with:
+          path: ${{ steps.composer-cache.outputs.dir }}
+          key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-composer-
+
+      - name: Install Composer dependencies
+        if: ${{ env.COMPOSER_INSTALL == true || env.LOCAL_PHP == '8.0-fpm' }}
+        run: |
+          docker-compose run --rm php composer --version
+
+          # The PHPUnit 7.x phar is not compatible with PHP 8 and won't be updated,
+          # as PHPUnit 7 is no longer supported. The Composer-installed PHPUnit should be
+          # used for PHP 8 testing instead.
+          if [ ${{ env.LOCAL_PHP }} == '8.0-fpm' ]; then
+            docker-compose run --rm php composer install --ignore-platform-reqs
+            echo "PHPUNIT_SCRIPT=php-composer" >> $GITHUB_ENV
+          else
+            docker-compose run --rm php composer install
+          fi
+
+      - name: Docker debug information
+        run: |
+          docker -v
+          docker-compose -v
+
+      - name: Start Docker environment
+        run: |
+          npm run env:start
+
+      - name: General debug information
+        run: |
+          npm --version
+          node --version
+          curl --version
+          git --version
+          svn --version
+
+      - name: Log running Docker containers
+        run: docker ps -a
+
+      - name: WordPress Docker container debug information
+        run: |
+          docker-compose run --rm mysql mysql --version
+          docker-compose run --rm php php --version
+          docker-compose run --rm php php -m
+          docker-compose run --rm php php -i
+          docker-compose run --rm php locale -a
+
+      - name: Install WordPress
+        run: npm run env:install
+
+      - name: Run PHPUnit tests
+        run: npm run test:${{ env.PHPUNIT_SCRIPT }} -- --verbose -c phpunit.xml.dist
+
+      - name: Run tests as a multisite install
+        run: npm run test:${{ env.PHPUNIT_SCRIPT }} -- --verbose -c tests/phpunit/multisite.xml