Issue #3418136 by shalini_jha, smustgrave, rohit sankhla: Add last() function...

Issue #3418136 by shalini_jha, smustgrave, rohit sankhla: Add last() function to ItemInterface/ItemList

(cherry picked from commit b7ce2ab9)

core/lib/Drupal/Core/TypedData/ListInterface.php

@@ -91,6 +91,14 @@ public function set($index, $value);
    */
   public function first();
 
+  /**
+   * Returns the last item in this list.
+   *
+   * @return \Drupal\Core\TypedData\TypedDataInterface|null
+   *   The last item in this list, or NULL if there are no items.
+   */
+  public function last(): ?TypedDataInterface;
+
   /**
    * Appends a new item to the list.
    *

core/lib/Drupal/Core/TypedData/Plugin/DataType/ItemList.php

@@ -303,4 +303,11 @@ public function __clone() {
     }
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function last(): ?TypedDataInterface {
+    return $this->get($this->count() - 1);
+  }
+
 }

core/tests/Drupal/KernelTests/Core/TypedData/TypedDataTest.php

@@ -695,4 +695,25 @@ public function testTypedDataValidation(): void {
     $this->assertSame('0.value', $violations[0]->getPropertyPath());
   }
 
+  /**
+   * Tests the last() method on typed data lists.
+   */
+  public function testTypedDataListsLast(): void {
+    // Create an ItemList with two string items.
+    $value = ['zero', 'one'];
+    $typed_data = $this->createTypedData(ListDataDefinition::create('string'), $value);
+
+    // Assert that the last item is the second one ('one').
+    $this->assertEquals('one', $typed_data->last()->getValue());
+
+    // Add another item to the list and check the last item.
+    $value[] = 'two';
+    $typed_data = $this->createTypedData(ListDataDefinition::create('string'), $value);
+    $this->assertEquals('two', $typed_data->last()->getValue());
+
+    // Check behavior with an empty list.
+    $typed_data = $this->createTypedData(ListDataDefinition::create('string'), []);
+    $this->assertNull($typed_data->last(), 'Empty list should return NULL.');
+  }
+
 }