diff --git a/src/Contracts/NestedSetCollection.php b/src/Contracts/NestedSetCollection.php
index c65040c..cb4162e 100644
--- a/src/Contracts/NestedSetCollection.php
+++ b/src/Contracts/NestedSetCollection.php
@@ -46,4 +46,32 @@ public function toTree($root = false): NestedSetCollection;
 	 * @return NestedSetCollection<Tmodel>
 	 */
 	public function toFlatTree($root = false): NestedSetCollection;
+
+	/**
+	 * Count the number of items in the collection.
+	 *
+	 * @return int
+	 */
+	public function count(): int;
+
+	/**
+	 * Get the values of a given key.
+	 *
+	 * @param string|int|array<array-key, string>|null $value
+	 * @param string|null                              $key
+	 *
+	 * @return \Illuminate\Support\Collection<array-key, mixed>
+	 */
+	public function pluck($value, $key = null);
+
+	/**
+	 * Run a map over each of the items.
+	 *
+	 * @template TMapValue
+	 *
+	 * @param callable(NodeModel, int): TMapValue $callback
+	 *
+	 * @return \Illuminate\Support\Collection<int, TMapValue>
+	 */
+	public function map(callable $callback);
 }
diff --git a/tests/NodeTest.php b/tests/NodeTest.php
index d9b93ac..b0c4d3e 100644
--- a/tests/NodeTest.php
+++ b/tests/NodeTest.php
@@ -1,9 +1,14 @@
 <?php
 
+namespace tests;
+
 use Illuminate\Database\Capsule\Manager as Capsule;
+use Illuminate\Database\Schema\Blueprint;
 use Kalnoy\Nestedset\NestedSet;
+use PHPUnit\Framework\TestCase;
+use tests\models\Category;
 
-class NodeTest extends PHPUnit\Framework\TestCase
+class NodeTest extends TestCase
 {
 	public static function setUpBeforeClass(): void
 	{
@@ -13,7 +18,7 @@ public static function setUpBeforeClass(): void
 
 		Capsule::disableQueryLog();
 
-		$schema->create('categories', function (Illuminate\Database\Schema\Blueprint $table) {
+		$schema->create('categories', function (Blueprint $table) {
 			$table->increments('id');
 			$table->string('name');
 			$table->softDeletes();
@@ -225,7 +230,7 @@ public function testCategoryMovesUp()
 
 	public function testFailsToInsertIntoChild()
 	{
-		$this->expectException(Exception::class);
+		$this->expectException(\Exception::class);
 
 		$node = $this->findCategory('notebooks');
 		$target = $node->children()->first();
@@ -235,7 +240,7 @@ public function testFailsToInsertIntoChild()
 
 	public function testFailsToAppendIntoItself()
 	{
-		$this->expectException(Exception::class);
+		$this->expectException(\Exception::class);
 
 		$node = $this->findCategory('notebooks');
 
@@ -244,7 +249,7 @@ public function testFailsToAppendIntoItself()
 
 	public function testFailsToPrependIntoItself()
 	{
-		$this->expectException(Exception::class);
+		$this->expectException(\Exception::class);
 
 		$node = $this->findCategory('notebooks');
 
@@ -339,7 +344,7 @@ public function testParentIdAttributeAccessorAppendsNode()
 
 	public function testFailsToSaveNodeUntilNotInserted()
 	{
-		$this->expectException(Exception::class);
+		$this->expectException(\Exception::class);
 
 		$node = new Category();
 		$node->save();
@@ -405,7 +410,7 @@ public function testSoftDeletedNodeisDeletedWhenParentIsDeleted()
 
 	public function testFailsToSaveNodeUntilParentIsSaved()
 	{
-		$this->expectException(Exception::class);
+		$this->expectException(\Exception::class);
 
 		$node = new Category(['title' => 'Node']);
 		$parent = new Category(['title' => 'Parent']);
diff --git a/tests/ScopedNodeTest.php b/tests/ScopedNodeTest.php
index 6886263..9e91cce 100644
--- a/tests/ScopedNodeTest.php
+++ b/tests/ScopedNodeTest.php
@@ -1,11 +1,13 @@
 <?php
 
+namespace tests;
+
 use Illuminate\Database\Capsule\Manager as Capsule;
 use Kalnoy\Nestedset\NestedSet;
+use PHPUnit\Framework\TestCase;
+use tests\models\MenuItem;
 
-include __DIR__ . '/models/MenuItem.php';
-
-class ScopedNodeTest extends PHPUnit\Framework\TestCase
+class ScopedNodeTest extends TestCase
 {
 	public static function setUpBeforeClass(): void
 	{
@@ -15,7 +17,7 @@ public static function setUpBeforeClass(): void
 
 		Capsule::disableQueryLog();
 
-		$schema->create('menu_items', function (Illuminate\Database\Schema\Blueprint $table) {
+		$schema->create('menu_items', function (\Illuminate\Database\Schema\Blueprint $table) {
 			$table->increments('id');
 			$table->unsignedInteger('menu_id');
 			$table->string('title')->nullable();
@@ -204,7 +206,7 @@ protected function assertOtherScopeNotAffected()
 
 	public function testAppendingToAnotherScopeFails()
 	{
-		$this->expectException(LogicException::class);
+		$this->expectException(\LogicException::class);
 
 		$a = MenuItem::find(1);
 		$b = MenuItem::find(3);
@@ -214,7 +216,7 @@ public function testAppendingToAnotherScopeFails()
 
 	public function testInsertingBeforeAnotherScopeFails()
 	{
-		$this->expectException(LogicException::class);
+		$this->expectException(\LogicException::class);
 
 		$a = MenuItem::find(1);
 		$b = MenuItem::find(3);
diff --git a/tests/models/Category.php b/tests/models/Category.php
index e3ce3a5..1f1e7d2 100644
--- a/tests/models/Category.php
+++ b/tests/models/Category.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace tests\models;
+
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\SoftDeletes;
 use Kalnoy\Nestedset\Contracts\Node;
diff --git a/tests/models/DuplicateCategory.php b/tests/models/DuplicateCategory.php
index 6a64503..63d5969 100644
--- a/tests/models/DuplicateCategory.php
+++ b/tests/models/DuplicateCategory.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace tests\models;
+
 use Illuminate\Database\Eloquent\Model;
 use Kalnoy\Nestedset\Contracts\Node;
 use Kalnoy\Nestedset\NodeTrait;
diff --git a/tests/models/MenuItem.php b/tests/models/MenuItem.php
index cadb9fa..e90cb47 100644
--- a/tests/models/MenuItem.php
+++ b/tests/models/MenuItem.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace tests\models;
+
 use Illuminate\Database\Eloquent\Model;
 use Kalnoy\Nestedset\Contracts\Node;
 use Kalnoy\Nestedset\NodeTrait;