Issue #3262587: Show warnings when starting an update

tests/src/Unit/ReadinessTraitTest.php

+<?php
+
+namespace Drupal\Tests\automatic_updates\Unit;
+
+use Drupal\automatic_updates\Validation\ReadinessTrait;
+use Drupal\package_manager\ValidationResult;
+use Drupal\system\SystemManager;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * @coversDefaultClass \Drupal\automatic_updates\Validation\ReadinessTrait
+ *
+ * @group automatic_updates
+ */
+class ReadinessTraitTest extends UnitTestCase {
+
+  use ReadinessTrait;
+
+  /**
+   * @covers ::getOverallSeverity
+   */
+  public function testOverallSeverity(): void {
+    // An error and a warning should be counted as an error.
+    $results = [
+      ValidationResult::createError(['Boo!']),
+      ValidationResult::createWarning(['Moo!']),
+    ];
+    $this->assertSame(SystemManager::REQUIREMENT_ERROR, $this->getOverallSeverity($results));
+
+    // If there are no results, but no errors, the results should be counted as
+    // a warning.
+    array_shift($results);
+    $this->assertSame(SystemManager::REQUIREMENT_WARNING, $this->getOverallSeverity($results));
+
+    // If there are just plain no results, we should get REQUIREMENT_OK.
+    array_shift($results);
+    $this->assertSame(SystemManager::REQUIREMENT_OK, $this->getOverallSeverity($results));
+  }
+
+}