diff --git a/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/respect_interface.php.inc b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/respect_interface.php.inc
new file mode 100644
index 000000000000..40f80500adc0
--- /dev/null
+++ b/packages/TypeDeclaration/tests/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/respect_interface.php.inc
@@ -0,0 +1,50 @@
+<?php
+
+namespace Rector\TypeDeclaration\Tests\Rector\ClassMethod\ReturnTypeDeclarationRector\Fixture;
+
+interface RespectInterface
+{
+    /**
+     * @return string
+     */
+    public function toString(): string;
+}
+
+class Respect implements RespectInterface
+{
+    /**
+     * @return string
+     */
+    public function toString(): string
+    {
+        throw new \RuntimeException('This method returns void but the return type hint has to remain "string".');
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\TypeDeclaration\Tests\Rector\ClassMethod\ReturnTypeDeclarationRector\Fixture;
+
+interface RespectInterface
+{
+    /**
+     * @return string
+     */
+    public function toString(): string;
+}
+
+class Respect implements RespectInterface
+{
+    /**
+     * @return string
+     */
+    public function toString(): string
+    {
+        throw new \RuntimeException('This method returns void but the return type hint has to remain "string".');
+    }
+}
+
+
+?>