Add WooCommerce version selection to Docker PHP test suite (https://github.com/woocommerce/woocommerce-admin/pull/6119)

* Add WooCommerce version selection

The WC_VERSION environment variable is added to the docker-compose config. If the variable is not set on the shell, it defaults to the minimum supported version (4.5.0)

The ENTRYPOINT is changed to automatically re-install the test suite when the version number is changed.

* Add documentation

* Add versioning to force image rebuild

plugins/woocommerce-admin/docker/wc-admin-php-test-suite/docker-compose.yml

@@ -3,11 +3,13 @@ version: "3"
 services:
   phpunit:
     build: "."
+    image: wc-admin-php-test-suite-phpunit:1.1.0
     volumes:
       - "test-suite:/tmp"
       - "../../:/app"
     environment:
       - WC_CORE_DIR=/tmp/wordpress/wp-content/plugins/woocommerce
+      - WC_VERSION=${WC_VERSION:-4.5.0}
       - DB_USER=root
       - DB_PASS=password
       - DB_NAME=wordpress_test

plugins/woocommerce-admin/docker/wc-admin-php-test-suite/entrypoint.sh

@@ -5,12 +5,35 @@ until mysqladmin ping -h"$DB_HOST" --silent; do
   >&2 echo "MySQL is unavailable - sleeping"
   sleep 2
 done
-  
+
 >&2 echo "MySQL is up - executing tests"
 
+# Function to install the test suite.
+function install {
+	# Delete previous state.
+	rm -f /tmp/.INSTALLED_WC_VERSION
+
+	# Run the install script.
+	bin/install-wp-tests.sh $DB_NAME $DB_USER $DB_PASS $DB_HOST latest true
+
+	# Remember the installed WooCommerce version.
+	echo "$WC_VERSION" > /tmp/.INSTALLED_WC_VERSION
+}
+
+# Run the install script if the installed WooCommerce version is unknown.
+if [ ! -f /tmp/.INSTALLED_WC_VERSION ]; then
+	install
+else
+	# Run the install script if the WooCommerce version has changed.
+	INSTALLED_WC_VERSION=`cat /tmp/.INSTALLED_WC_VERSION`
+	if [ "$WC_VERSION" != "$INSTALLED_WC_VERSION" ]; then
+		install
+	fi
+fi
+
 # Run the install script if the WordPress directory is not found.
 if [ ! -d /tmp/wordpress-tests-lib ]; then
-	bin/install-wp-tests.sh $DB_NAME $DB_USER $DB_PASS $DB_HOST latest true
+	install
 fi
 
 exec phpunit "$@"

plugins/woocommerce-admin/docker/wc-admin-php-test-suite/readme.md

@@ -15,7 +15,7 @@ This runs the the `phpunit` container with `docker-compose -f run --rm phpunit`.
 
 ## Re-install Test Suite
 
-Re-installation is useful to update WordPress and WooCommerce to the latest versions. To do this, remove the existing `test-suite` volume using Docker. For example:
+Re-installation is useful to update WordPress to the latest version. To do this, remove the existing `test-suite` volume using Docker. For example:
 
 ```shell
 docker volume rm -f wc-admin-php-test-suite_test-suite
@@ -30,3 +30,15 @@ PHPUnit flags can be passed to the npm script. To limit testing to a single test
 ```shell
 npm run test:php -- --filter=<name of test>
 ```
+
+## Selecting the WooCommerce Version
+
+By default, the minimum supported version of WooCommerce is used to build the test suite. This can be overridden with an environment variable.
+
+```shell
+WC_VERSION=4.9.0 npm run test:php
+```
+
+## Development
+
+When comitting changes to the `Dockerfile` or `entrypoint.sh` files, bump the `wc-admin-php-test-suite-phpunit` image tag version in `docker-composer.xml`. This will result in an image  rebuild automatically upon next use, enabling the changes to be applied for all users.