chore: improve test suite (#3814)

Allows running tests without constantly running `composer install` on each extension.

php-packages/testing/bootstrap/monorepo.php

@@ -0,0 +1,42 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+/*
+|
+| This is specific to a monorepo setup. If you're using a single
+| repository for your extension, checkout the extension skeleton
+| at https://github.com/flarum/cli/tree/main/boilerplate/skeleton/extension.
+|
+| ---------------------------------------------------------------
+|
+| We symlink local vendor bins to the framework vendor bin
+| to be able to run scripts from the extension directory.
+|
+| We also use a `FLARUM_TEST_VENDOR_PATH` environment variable
+| to tell each extension where to find the framework vendor,
+| instead of a SetupScript property, because it is also needed
+| when running the tests.
+|
+*/
+
+$monorepoVendor = __DIR__.'/../../../vendor';
+
+// The root directory of the extension where tests are run from.
+$localVendor = getcwd().'/vendor';
+
+if (! file_exists("$localVendor/bin")) {
+    mkdir("$localVendor");
+    symlink("$monorepoVendor/bin", "$localVendor/bin");
+}
+
+require $monorepoVendor.'/autoload.php';
+
+putenv('FLARUM_TEST_VENDOR_PATH='.$monorepoVendor);
+
+return new Flarum\Testing\integration\Setup\SetupScript();