add test case for nested generic arg with Self

Author: Young-Flash

crates/ide-assists/src/handlers/extract_struct_from_enum_variant.rs

@@ -461,6 +461,23 @@ enum Foo {
             r#"
 struct Bar{ node: Box<Foo> }
 
+enum Foo {
+    Bar(Bar),
+    Nil,
+}
+"#,
+        );
+        check_assist(
+            extract_struct_from_enum_variant,
+            r#"
+enum Foo {
+    Bar $0{ node: Box<Self>, a: Arc<Box<Self>> },
+    Nil,
+}
+"#,
+            r#"
+struct Bar{ node: Box<Foo>, a: Arc<Box<Foo>> }
+
 enum Foo {
     Bar(Bar),
     Nil,