diff --git a/test/data/duplicate-mapping-key.loader-error b/test/data/duplicate-mapping-key.loader-error
new file mode 100644
index 0000000..55bce77
--- /dev/null
+++ b/test/data/duplicate-mapping-key.loader-error
@@ -0,0 +1,2 @@
+a: 1
+a: 2
\ No newline at end of file