Add assertion to check non-empty result in CacheTypeTest

Ensure `$ro` cast to string is not empty in the `testFetch` method. This additional assertion enhances the test to validate that the resource's returned data is not only a specific format but also non-empty.

tests/CacheTypeTest.php

@@ -50,6 +50,8 @@ public function testValue(): void
         $this->assertSame('1' . $time, $ro->view);
         $ro = $this->resource->get($uri);
         (string) $ro;
+        $result = (string) $ro;
+        $this->assertNotEmpty($result);
         $this->assertSame('2' . $time, $ro->view);
     }