Fix clone behavior of QueryBuilder

src/QueryBuilder.php

@@ -130,6 +130,16 @@ public function __call($name, $arguments)
 
         return $result;
     }
+
+    public function clone()
+    {
+        return clone $this;
+    }
+
+    public function __clone()
+    {
+        $this->subject = clone $this->subject;
+    }
 
     public function __get($name)
     {

tests/QueryBuilderTest.php

@@ -297,4 +297,33 @@ public function it_does_not_lose_pivot_values_with_belongs_to_many_relation()
             $foundTestModel->pivot->location
         );
     }
+
+
+    /** @test */
+    public function it_clones_the_subject_upon_cloning()
+    {
+        $queryBuilder = QueryBuilder::for(TestModel::class);
+
+        $queryBuilder1 = (clone $queryBuilder)->where('id', 1);
+        $queryBuilder2 = (clone $queryBuilder)->where('name', 'John Doe');
+
+        $this->assertNotSame(
+            $queryBuilder1->toSql(),
+            $queryBuilder2->toSql()
+        );
+    }
+
+    /** @test */
+    public function it_supports_clone_as_method()
+    {
+        $queryBuilder = QueryBuilder::for(TestModel::class);
+
+        $queryBuilder1 = $queryBuilder->clone()->where('id', 1);
+        $queryBuilder2 = $queryBuilder->clone()->where('name', 'John Doe');
+
+        $this->assertNotSame(
+            $queryBuilder1->toSql(),
+            $queryBuilder2->toSql()
+        );
+    }
 }