Issue #2843328 by mpdonadio, alexpott, Mile23, cburschka, xjm: Enforce minimum PHP version in composer dependencies

core/includes/bootstrap.inc

@@ -21,6 +21,9 @@ use Drupal\Core\StringTranslation\TranslatableMarkup;
  * Minimum supported version of PHP.
  *
  * Drupal cannot be installed on versions of PHP older than this version.
+ *
+ * @todo Move this to an appropriate autoloadable class. See
+ *   https://www.drupal.org/project/drupal/issues/2908079
  */
 const DRUPAL_MINIMUM_PHP = '5.5.9';
 
@@ -30,6 +33,9 @@ const DRUPAL_MINIMUM_PHP = '5.5.9';
  * Sites installing Drupal on PHP versions lower than this will see a warning
  * message, but Drupal can still be installed. Used for (e.g.) PHP versions
  * that have reached their EOL or will in the near future.
+ *
+ * @todo Move this to an appropriate autoloadable class. See
+ *   https://www.drupal.org/project/drupal/issues/2908079
  */
 const DRUPAL_RECOMMENDED_PHP = '7.1';
 
@@ -39,6 +45,9 @@ const DRUPAL_RECOMMENDED_PHP = '7.1';
  * 64M was chosen as a minimum requirement in order to allow for additional
  * contributed modules to be installed prior to hitting the limit. However,
  * 40M is the target for the Standard installation profile.
+ *
+ * @todo Move this to an appropriate autoloadable class. See
+ *   https://www.drupal.org/project/drupal/issues/2908079
  */
 const DRUPAL_MINIMUM_PHP_MEMORY_LIMIT = '64M';
 

core/tests/Drupal/Tests/ComposerIntegrationTest.php

@@ -2,6 +2,8 @@
 
 namespace Drupal\Tests;
 
+use Composer\Semver\Semver;
+
 /**
  * Tests Composer integration.
  *
@@ -9,6 +11,15 @@ namespace Drupal\Tests;
  */
 class ComposerIntegrationTest extends UnitTestCase {
 
+  /**
+   * The minimum PHP version supported by Drupal.
+   *
+   * @see https://www.drupal.org/docs/8/system-requirements/web-server
+   *
+   * @todo Remove as part of https://www.drupal.org/node/2908079
+   */
+  const MIN_PHP_VERSION = '5.5.9';
+
   /**
    * Gets human-readable JSON error messages.
    *
@@ -171,6 +182,34 @@ class ComposerIntegrationTest extends UnitTestCase {
     }
   }
 
+  /**
+   * Tests package requirements for the minimum supported PHP version by Drupal.
+   *
+   * @todo This can be removed when DrupalCI supports dependency regression
+   *   testing in https://www.drupal.org/node/2874198
+   */
+  public function testMinPHPVersion() {
+    // Check for lockfile in the application root. If the lockfile does not
+    // exist, then skip this test.
+    $lockfile = $this->root . '/composer.lock';
+    if (!file_exists($lockfile)) {
+      $this->markTestSkipped('/composer.lock is not available.');
+    }
+
+    $lock = json_decode(file_get_contents($lockfile), TRUE);
+
+    // Check the PHP version for each installed non-development  package. The
+    // testing infrastructure uses the uses the development packages, and may
+    // update them for particular environment configurations. In particular,
+    // PHP 7.2+ require an updated version of phpunit, which is incompatible
+    // with Drupal's minimum PHP requirement.
+    foreach ($lock['packages'] as $package) {
+      if (isset($package['require']['php'])) {
+        $this->assertTrue(Semver::satisfies(static::MIN_PHP_VERSION, $package['require']['php']), $package['name'] . ' has a PHP dependency requirement of "' . $package['require']['php'] . '"');
+      }
+    }
+  }
+
   // @codingStandardsIgnoreStart
   /**
    * The following method is copied from \Composer\Package\Locker.