diff --git a/core/modules/field/src/Tests/DisplayApiTest.php b/core/modules/field/src/Tests/DisplayApiTest.php
index 60f1fdf..2fe67a3 100644
--- a/core/modules/field/src/Tests/DisplayApiTest.php
+++ b/core/modules/field/src/Tests/DisplayApiTest.php
@@ -17,6 +17,13 @@
 class DisplayApiTest extends FieldUnitTestBase {
 
   /**
+   * The field name to use in this test.
+   *
+   * @var string
+   */
+  protected $fieldName;
+
+  /**
    * The field label to use in this test.
    *
    * @var string
@@ -55,18 +62,18 @@ protected function setUp() {
     parent::setUp();
 
     // Create a field and its storage.
-    $this->field_name = 'test_field';
+    $this->fieldName = 'test_field';
     $this->label = $this->randomMachineName();
     $this->cardinality = 4;
 
     $field_storage = array(
-      'field_name' => $this->field_name,
+      'field_name' => $this->fieldName,
       'entity_type' => 'entity_test',
       'type' => 'test_field',
       'cardinality' => $this->cardinality,
     );
     $field = array(
-      'field_name' => $this->field_name,
+      'field_name' => $this->fieldName,
       'entity_type' => 'entity_test',
       'bundle' => 'entity_test',
       'label' => $this->label,
@@ -91,18 +98,18 @@ protected function setUp() {
     entity_create('field_config', $field)->save();
     // Create a display for the default view mode.
     entity_get_display($field['entity_type'], $field['bundle'], 'default')
-      ->setComponent($this->field_name, $this->displayOptions['default'])
+      ->setComponent($this->fieldName, $this->displayOptions['default'])
       ->save();
     // Create a display for the teaser view mode.
     EntityViewMode::create(array('id' =>  'entity_test.teaser', 'targetEntityType' => 'entity_test'))->save();
     entity_get_display($field['entity_type'], $field['bundle'], 'teaser')
-      ->setComponent($this->field_name, $this->displayOptions['teaser'])
+      ->setComponent($this->fieldName, $this->displayOptions['teaser'])
       ->save();
 
     // Create an entity with values.
     $this->values = $this->_generateTestFieldValues($this->cardinality);
     $this->entity = entity_create('entity_test');
-    $this->entity->{$this->field_name}->setValue($this->values);
+    $this->entity->{$this->fieldName}->setValue($this->values);
     $this->entity->save();
   }
 
@@ -110,7 +117,7 @@ protected function setUp() {
    * Tests the FieldItemListInterface::view() method.
    */
   function testFieldItemListView() {
-    $items = $this->entity->get($this->field_name);
+    $items = $this->entity->get($this->fieldName);
 
     // No display settings: check that default display settings are used.
     $build = $items->view();
@@ -280,16 +287,16 @@ function testFieldEmpty() {
     );
     // $this->entity is set by the setUp() method and by default contains 4
     // numeric values.  We only want to test the display of this one field.
-    $build = $this->entity->get($this->field_name)->view($display);
+    $build = $this->entity->get($this->fieldName)->view($display);
     $this->render($build);
     // The test field by default contains values, so should not display the
     // default "empty" text.
     $this->assertNoText($display['settings']['test_empty_string']);
 
     // Now remove the values from the test field and retest.
-    $this->entity->{$this->field_name} = array();
+    $this->entity->{$this->fieldName} = array();
     $this->entity->save();
-    $build = $this->entity->get($this->field_name)->view($display);
+    $build = $this->entity->get($this->fieldName)->view($display);
     $this->render($build);
     // This time, as the field values have been removed, we *should* show the
     // default "empty" text.
diff --git a/core/modules/field/src/Tests/ShapeItemTest.php b/core/modules/field/src/Tests/ShapeItemTest.php
index 9f7df3b..6f6c9fa 100644
--- a/core/modules/field/src/Tests/ShapeItemTest.php
+++ b/core/modules/field/src/Tests/ShapeItemTest.php
@@ -64,11 +64,11 @@ public function testShapeItem() {
     $id = $entity->id();
     $entity = entity_load('entity_test', $id);
     $this->assertTrue($entity->{$this->fieldName} instanceof FieldItemListInterface, 'Field implements interface.');
-    $this->assertTrue($entity->{$this->fieldName}[0] instanceof FieldItemInterface, 'Field item implements interface.');
+    $this->assertTrue($entity->{$this->field_name}[0] instanceof FieldItemInterface, 'Field item implements interface.');
     $this->assertEqual($entity->{$this->fieldName}->shape, $shape);
     $this->assertEqual($entity->{$this->fieldName}->color, $color);
-    $this->assertEqual($entity->{$this->fieldName}[0]->shape, $shape);
-    $this->assertEqual($entity->{$this->fieldName}[0]->color, $color);
+    $this->assertEqual($entity->{$this->field_name}[0]->shape, $shape);
+    $this->assertEqual($entity->{$this->field_name}[0]->color, $color);
 
     // Verify changing the field value.
     $new_shape = 'circle';
diff --git a/core/modules/field/src/Tests/TestItemTest.php b/core/modules/field/src/Tests/TestItemTest.php
index 7aa4679..681561c 100644
--- a/core/modules/field/src/Tests/TestItemTest.php
+++ b/core/modules/field/src/Tests/TestItemTest.php
@@ -63,9 +63,9 @@ public function testTestItem() {
     $id = $entity->id();
     $entity = entity_load('entity_test', $id);
     $this->assertTrue($entity->{$this->fieldName} instanceof FieldItemListInterface, 'Field implements interface.');
-    $this->assertTrue($entity->{$this->fieldName}[0] instanceof FieldItemInterface, 'Field item implements interface.');
+    $this->assertTrue($entity->{$this->field_name}[0] instanceof FieldItemInterface, 'Field item implements interface.');
     $this->assertEqual($entity->{$this->fieldName}->value, $value);
-    $this->assertEqual($entity->{$this->fieldName}[0]->value, $value);
+    $this->assertEqual($entity->{$this->field_name}[0]->value, $value);
 
     // Verify changing the field value.
     $new_value = rand(1, 10);
diff --git a/core/modules/field/src/Tests/TranslationTest.php b/core/modules/field/src/Tests/TranslationTest.php
index 6e1d3fc..5cd6504 100644
--- a/core/modules/field/src/Tests/TranslationTest.php
+++ b/core/modules/field/src/Tests/TranslationTest.php
@@ -133,7 +133,7 @@ function testTranslatableFieldSaveLoad() {
     foreach ($field_translations as $langcode => $items) {
       $result = TRUE;
       foreach ($items as $delta => $item) {
-        $result = $result && $item['value'] == $entity->getTranslation($langcode)->{$this->fieldName}[$delta]->value;
+        $result = $result && $item['value'] == $entity->getTranslation($langcode)->{fieldName}[$delta]->value;
       }
       $this->assertTrue($result, format_string('%language translation correctly handled.', array('%language' => $langcode)));
     }