diff --git a/.github/workflows/mutation.yml b/.github/workflows/mutation.yml
index 6d35498..aa68e8a 100644
--- a/.github/workflows/mutation.yml
+++ b/.github/workflows/mutation.yml
@@ -21,7 +21,59 @@ jobs:
   mutation:
     uses: php-forge/actions/.github/workflows/infection.yml@main
     with:
+      extensions: pdo, pdo_pgsql, pdo_sqlite
+      framework-options: --test-framework-options="--group=sqlite,mutation"
+      hook: |
+        # Config MySQL with Docker
+        docker run -d \
+          --name mysql-test \
+          -e MYSQL_ROOT_PASSWORD=root \
+          -e MYSQL_DATABASE=yiitest \
+          -e MYSQL_USER=test \
+          -e MYSQL_PASSWORD=test \
+          -p 3306:3306 \
+          --health-cmd="mysqladmin ping -h localhost" \
+          --health-interval=10s \
+          --health-timeout=5s \
+          --health-retries=5 \
+          mysql:8.0
+
+        # Config PostgreSQL with Docker
+        docker run -d \
+          --name postgres-test \
+          -e POSTGRES_DB=yiitest \
+          -e POSTGRES_USER=root \
+          -e POSTGRES_PASSWORD=root \
+          -p 5432:5432 \
+          --health-cmd="pg_isready -U postgres" \
+          --health-interval=10s \
+          --health-timeout=5s \
+          --health-retries=3 \
+          postgres:16
+
+        # Wait for MySQL to be ready
+        echo "Waiting for MySQL to be ready..."
+        timeout 120s bash -c 'until docker exec mysql-test mysqladmin ping -h localhost --silent; do sleep 3; done'
+
+        # Wait for PostgreSQL to be ready
+        echo "Waiting for PostgreSQL to be ready..."
+        timeout 60s bash -c 'until docker exec postgres-test pg_isready -U postgres; do sleep 2; done'
+
+        # Check if MySQL is running
+        echo "Testing MySQL connection..."
+        docker exec mysql-test mysql -u root -proot -e "SELECT VERSION();"
+
+        # Check if PostgreSQL is running
+        echo "Testing PostgreSQL connection..."
+        docker exec postgres-test psql -U root -d yiitest -c "SELECT version();"
+
+        # Set environment variables for MySQL and PostgreSQL
+        echo "MYSQL_DSN=mysql:host=localhost;port=3306;dbname=yiitest" >> $GITHUB_ENV
+        echo "MYSQL_USERNAME=root" >> $GITHUB_ENV
+        echo "MYSQL_PASSWORD=root" >> $GITHUB_ENV
+        echo "PGSQL_DSN=pgsql:host=localhost;port=5432;dbname=yiitest" >> $GITHUB_ENV
+        echo "PGSQL_USERNAME=root" >> $GITHUB_ENV
+        echo "PGSQL_PASSWORD=root" >> $GITHUB_ENV
       phpstan: true
-      framework-options: --test-framework-options="--group=sqlite"
     secrets:
       STRYKER_DASHBOARD_API_KEY: ${{ secrets.STRYKER_DASHBOARD_API_KEY }}
diff --git a/tests/mysql/MutationTest.php b/tests/mysql/MutationTest.php
new file mode 100644
index 0000000..53eac97
--- /dev/null
+++ b/tests/mysql/MutationTest.php
@@ -0,0 +1,84 @@
+<?php
+
+declare(strict_types=1);
+
+namespace yii2\extensions\nestedsets\tests\mysql;
+
+use PHPUnit\Framework\Attributes\Group;
+use yii2\extensions\nestedsets\tests\support\model\MultipleTree;
+use yii2\extensions\nestedsets\tests\TestCase;
+
+#[Group('mutation')]
+final class MutationTest extends TestCase
+{
+    protected string $driverName = 'mysql';
+    protected string|null $dsn = 'mysql:host=127.0.0.1;dbname=yiitest;charset=utf8mb4';
+    protected string $password = 'root';
+    protected string $username = 'root';
+
+    public function testLeavesMethodRequiresLeftAttributeOrderingForConsistentResults(): void
+    {
+        $this->createDatabase();
+
+        $root = new MultipleTree(['name' => 'Root']);
+
+        $root->makeRoot();
+
+        $leaf1 = new MultipleTree(['name' => 'Leaf A']);
+
+        $leaf1->appendTo($root);
+
+        $leaf2 = new MultipleTree(['name' => 'Leaf B']);
+
+        $leaf2->appendTo($root);
+
+        $initialLeaves = MultipleTree::find()->leaves()->all();
+
+        self::assertCount(
+            2,
+            $initialLeaves,
+            "Should have exactly '2' initial leaf nodes.",
+        );
+
+        $command = $this->getDb()->createCommand();
+
+        $command->update('multiple_tree', ['lft' => 3, 'rgt' => 4], ['name' => 'Leaf B'])->execute();
+        $command->update('multiple_tree', ['lft' => 5, 'rgt' => 6], ['name' => 'Leaf A'])->execute();
+        $command->update('multiple_tree', ['lft' => 1, 'rgt' => 7], ['name' => 'Root'])->execute();
+
+        $leaves = MultipleTree::find()->leaves()->all();
+
+        /** @phpstan-var array<array{name: string, lft: int}> */
+        $expectedLeaves = [
+            ['name' => 'Leaf B', 'lft' => 3],
+            ['name' => 'Leaf A', 'lft' => 5],
+        ];
+
+        self::assertCount(
+            2,
+            $leaves,
+            "Should return exactly '2' leaf nodes.",
+        );
+
+        foreach ($leaves as $index => $leaf) {
+            self::assertInstanceOf(
+                MultipleTree::class,
+                $leaf,
+                "Leaf at index {$index} should be an instance of 'MultipleTree'.",
+            );
+
+            if (isset($expectedLeaves[$index])) {
+                self::assertEquals(
+                    $expectedLeaves[$index]['name'],
+                    $leaf->getAttribute('name'),
+                    "Leaf at index {$index} should be {$expectedLeaves[$index]['name']} in correct order.",
+                );
+                self::assertEquals(
+                    $expectedLeaves[$index]['lft'],
+                    $leaf->getAttribute('lft'),
+                    "Leaf at index {$index} should have left value {$expectedLeaves[$index]['lft']}.",
+                );
+            }
+        }
+    }
+}
diff --git a/tests/pgsql/MutationTest.php b/tests/pgsql/MutationTest.php
new file mode 100644
index 0000000..a6ded69
--- /dev/null
+++ b/tests/pgsql/MutationTest.php
@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+namespace yii2\extensions\nestedsets\tests\pgsql;
+
+use PHPUnit\Framework\Attributes\Group;
+use yii2\extensions\nestedsets\tests\TestCase;
+
+#[Group('mutation')]
+final class MutationTest extends TestCase
+{
+    protected string $driverName = 'pgsql';
+    protected string|null $dsn = 'pgsql:host=localhost;dbname=yiitest;port=5432;';
+    protected string $password = 'root';
+    protected string $username = 'root';
+
+    public function testChildrenMethodRequiresOrderByForCorrectTreeTraversal(): void
+    {
+        $expectedOrder = ['Child A', 'Child B', 'Child C'];
+
+        $treeStructure = [
+            ['name' => 'Root', 'children' => ['Child B', 'Child C', 'Child A']],
+        ];
+
+        $updates = [
+            ['name' => 'Child B', 'lft' => 4, 'rgt' => 5],
+            ['name' => 'Child C', 'lft' => 6, 'rgt' => 7],
+            ['name' => 'Child A', 'lft' => 2, 'rgt' => 3],
+            ['name' => 'Root', 'rgt' => 8],
+        ];
+
+        $tree = $this->createTreeStructure($treeStructure, $updates);
+        $nodeList = $tree->children()->all();
+
+        $this->assertNodesInCorrectOrder($nodeList, $expectedOrder, 'Child');
+    }
+}