Add full string assertion for Document

src/Document.php

@@ -8,8 +8,9 @@ use PHPUnit\Framework\Assert;
 use ReflectionClass;
 use ReflectionMethod;
 use ReflectionProperty;
+use Spatie\LaravelData\Data;
 
-abstract class Document
+abstract class Document extends Data
 {
     abstract public function basename(): string;
 
@@ -35,6 +36,15 @@ abstract class Document
         );
     }
 
+    public function assertIsContent(string $content): void
+    {
+        Assert::assertEquals(
+            $content,
+            $this->renderBody(),
+            "Failed asserting that Content is {$content}"
+        );
+    }
+
     /**
      * @param array<int, string> $content
      */