Issue #2910445 by pfrenssen: Add a warning to the status report if config is writable

config_readonly.install

+<?php
+
+/**
+ * @file
+ * Install, uninstall, requirements and schema hooks for Config Read-only mode.
+ */
+
+use Drupal\Core\Site\Settings;
+
+/**
+ * Implements hook_requirements().
+ */
+function config_readonly_requirements($phase) {
+  $requirements = [];
+
+  if ($phase == 'runtime') {
+    if (!Settings::get('config_readonly')) {
+      $requirements['config_readonly'] = [
+        'title' => t('Config Read-only mode'),
+        'description' => t('The Config Read-only module is enabled but not active.'),
+        'severity' => REQUIREMENT_WARNING,
+        'value' => t('Config is writable'),
+      ];
+    }
+    else {
+      $requirements['config_readonly'] = [
+        'title' => t('Config Read-only mode'),
+        'description' => t('The Config Read-only module is enabled and active.'),
+        'severity' => REQUIREMENT_INFO,
+        'value' => t('Config is readonly'),
+      ];
+    }
+  }
+
+  return $requirements;
+}

tests/src/Functional/ReadOnlyConfigTest.php

@@ -141,4 +141,24 @@ class ReadOnlyConfigTest extends ReadOnlyConfigTestBase {
     $this->assertSession()->pageTextContains($this->message);
   }
 
+  /**
+   * Test the status page to ensure the correct message is displayed.
+   *
+   * @see https://www.drupal.org/project/config_readonly/issues/2910445
+   */
+  public function testModuleStatusPage() {
+    // Verify if we can successfully access file system route.
+    $status_url = Url::fromRoute('system.status');
+    $this->drupalGet($status_url);
+    $this->assertSession()->statusCodeEquals(200);
+    // Status page displays REQUIREMENT_WARNING because read-only is disabled.
+    $this->assertSession()->pageTextContains("The Config Read-only module is enabled but not active.");
+
+    // Switch forms to read-only.
+    $this->turnOnReadOnlySetting();
+    $this->drupalGet($status_url);
+    // Status page displays REQUIREMENT_INFO because read-only is enabled.
+    $this->assertSession()->pageTextContains("The Config Read-only module is enabled and active.");
+  }
+
 }