Issue #3328058: Expand the phpunit test coverage for module_filter

tests/modules/red/red.permissions.yml

+'buy_f':
+  title: 'Buy flowers'
+  description: 'The description is not used for filtering'
+'send':
+  title: 'Send flowers'

tests/modules/yellow/yellow.permissions.yml

+'buy_b':
+  title: 'Buy fruit'

tests/src/FunctionalJavascript/ModuleFilterJavascriptPermissionsTest.php

+<?php
+
+namespace Drupal\Tests\module_filter\FunctionalJavascript;
+
+/**
+ * Tests the Permisions tab on admin/people/permissions.
+ *
+ * @group module_filter
+ */
+class ModuleFilterJavascriptPermissionsTest extends ModuleFilterJavascriptTestBase {
+
+  /**
+   * Tests the filtering of permissions.
+   */
+  public function testPermissionsFiltering() {
+    /** @var \Drupal\Tests\WebAssert $assert */
+    $assert = $this->assertSession();
+
+    $this->drupalLogin($this->adminUser);
+    $this->drupalGet('admin/people/permissions');
+    $page = $this->getSession()->getPage();
+
+    // Check hat the test modules and their permissions are shown by default.
+    $assert->pageTextContains('Roses');
+    $assert->pageTextContains('Buy flowers');
+    $assert->pageTextContains('Send flowers');
+    $assert->pageTextContains('Banana');
+    $assert->pageTextContains('Buy fruit');
+
+    // Enter 'ses' as the filter and check that the Red Roses module is
+    // displayed and both of its permissions are displayed. Check that the other
+    // module and its permissions are not displayed. This shows that filtering
+    // works on the module's readable name.
+    $page->fillField('edit-text', 'ses');
+    $this->waitForNoText('Banana');
+    $assert->pageTextContains('Roses');
+    $assert->pageTextContains('Buy flowers');
+    $assert->pageTextContains('Send flowers');
+    $assert->pageTextNotContains('Banana');
+    $assert->pageTextNotContains('Buy fruit');
+  }
+
+}

tests/src/FunctionalJavascript/ModuleFilterJavascriptTestBase.php

@@ -51,6 +51,7 @@ abstract class ModuleFilterJavascriptTestBase extends WebDriverTestBase {
     // Create an administrator user with the required permissions.
     $this->adminUser = $this->drupalCreateUser([
       'administer modules',
+      'administer permissions',
     ]);
     $this->adminUser->set('name', 'Minnie the Admin')->save();
   }