[10.x] Add assertViewEmpty to TestView (#49558)

* Add assertEmpty to TestView

* Update TestView.php

---------

Co-authored-by: Taylor Otwell <[email protected]>

Author: dwightwatson

src/Illuminate/Testing/TestView.php

@@ -106,6 +106,16 @@ public function assertViewMissing($key)
         return $this;
     }
 
+    /**
+     * Assert that the view's rendered content is empty.
+     */
+    public function assertViewEmpty()
+    {
+        PHPUnit::assertEmpty($this->rendered);
+
+        return true;
+    }
+
     /**
      * Assert that the given string is contained within the view.
      *