Issue #2671446 by heykarthikwithu, mikeker: The Boolean field formatter does not provide a settings summary

core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/BooleanFormatter.php

@@ -114,6 +114,30 @@ class BooleanFormatter extends FormatterBase {
     return $form;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function settingsSummary() {
+    $summary = [];
+    $setting = $this->getSetting('format');
+
+    if ($setting == 'custom') {
+      $summary[] = $this->t('Custom text: @true_label / @false_label', [
+        '@true_label' => $this->getSetting('format_custom_true'),
+        '@false_label' => $this->getSetting('format_custom_false'),
+      ]);
+    }
+    else {
+      $formats = $this->getOutputFormats();
+      $summary[] = $this->t('Display: @true_label / @false_label', [
+        '@true_label' => $formats[$setting][0],
+        '@false_label' => $formats[$setting][1],
+      ]);
+    }
+
+    return $summary;
+  }
+
   /**
    * {@inheritdoc}
    */

core/modules/field/src/Tests/Boolean/BooleanFormatterSettingsTest.php

@@ -125,6 +125,12 @@ class BooleanFormatterSettingsTest extends WebTestBase {
       }
       $this->assertText(SafeMarkup::format($default, array('@on' => $values[0], '@off' => $values[1])));
     }
+
+    foreach ($settings as $values) {
+      $this->drupalGet('admin/structure/types/manage/' . $this->bundle . '/display');
+      $result = $this->xpath('//div[contains(@class, :class) and contains(text(), :text)]', [':class' => 'field-plugin-summary', ':text' => 'Display: TRUE / FALSE']);
+      $this->assertEqual(count($result), 1, "Boolean formatter settings summary exist.");
+    }
   }
 
 }