Add test

Author: VincentLanglet

tests/PHPStan/Rules/Methods/data/bug-12739.php

@@ -39,6 +39,15 @@ public static function getClassIdentify() : string {
 	}
 }
 
+/**
+ * @extends ScalarType<uppercase-string>
+ */
+class MyUpperString extends ScalarType {
+	public static function getClassIdentify() : string {
+		return MyUpperString::class;
+	}
+}
+
 /**
  * @extends ScalarType<class-string>
  */