Build/Test Tools: Improve messaging when PHPUnit Polyfills cannot be …

…found.

Previously, two situations were taken in to account:
1. The `WP_TESTS_PHPUNIT_POLYFILLS_PATH` constant is defined => show message specific to that constant not being set correctly.
    This message would typically be shown for plugin/theme integration tests which are already aware of the changes in WP 5.9.
2. The constant is not defined => show a message to run `composer update`.
    This message is intended for people trying to run the WP Core tests.

This left two situations unaccounted for:
- Someone trying to run the WP Core tests, but not having set the `WP_RUN_CORE_TESTS` constant or not having set it to `1`.
- Someone trying to run plugin/theme integration tests without the new `WP_TESTS_PHPUNIT_POLYFILLS_PATH` constant being defined as they are not (yet) aware of the changes made in WP 5.9.

The changes made in this commit, are intended to improve the error messages displayed in those situations.

Follow-up to [51598], [51810].

Props jrf, schlessera, hellofromTonya, jeherve, lucatume.
See #46149.

git-svn-id: https://develop.svn.wordpress.org/trunk@51811 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/includes/bootstrap.php

@@ -105,15 +105,19 @@
 
 	if ( $phpunit_polyfills_error || ! file_exists( $phpunit_polyfills_autoloader ) ) {
 		echo 'Error: The PHPUnit Polyfills library is a requirement for running the WP test suite.' . PHP_EOL;
-		if ( isset( $phpunit_polyfills_path ) ) {
+		if ( defined( 'WP_TESTS_PHPUNIT_POLYFILLS_PATH' ) ) {
 			printf(
 				'The PHPUnit Polyfills autoload file was not found in "%s"' . PHP_EOL,
 				WP_TESTS_PHPUNIT_POLYFILLS_PATH
 			);
 			echo 'Please verify that the file path provided in the WP_TESTS_PHPUNIT_POLYFILLS_PATH constant is correct.' . PHP_EOL;
-		} else {
+		} elseif ( defined( 'WP_RUN_CORE_TESTS' ) && WP_RUN_CORE_TESTS ) {
 			echo 'You need to run `composer update` before running the tests.' . PHP_EOL;
 			echo 'Once the dependencies are installed, you can run the tests using the Composer-installed version of PHPUnit or using a PHPUnit phar file, but the dependencies do need to be installed whichever way the tests are run.' . PHP_EOL;
+		} else {
+			echo 'If you are trying to run plugin/theme integration tests, make sure the PHPUnit Polyfills library is available and either load the autoload file of this library in your own test bootstrap before calling the WP Core test bootstrap file; or set the path to the PHPUnit Polyfills library in a "WP_TESTS_PHPUNIT_POLYFILLS_PATH" constant to allow the WP Core bootstrap to load the Polyfills.' . PHP_EOL . PHP_EOL;
+			echo 'If you are trying to run the WP Core tests, make sure to set the "WP_RUN_CORE_TESTS" constant to 1 and run `composer update` before running the tests.' . PHP_EOL;
+			echo 'Once the dependencies are installed, you can run the tests using the Composer-installed version of PHPUnit or using a PHPUnit phar file, but the dependencies do need to be installed whichever way the tests are run.' . PHP_EOL;
 		}
 		exit( 1 );
 	}