Fix map/array encoding with length 31
diff --git a/test/qcbor_encode_tests.h b/test/qcbor_encode_tests.h
index ae0241a..6f921c2 100644
--- a/test/qcbor_encode_tests.h
+++ b/test/qcbor_encode_tests.h
@@ -116,6 +116,12 @@
  */
 int SimpleValuesIndefiniteLengthTest1(void);
 
+/*
+ Indefinite length arrays and maps use the 'magic' number 31, verify that
+ everything with length 31 still works properly
+ */
+int EncodeLengthThirtyoneTest(void);
+
 
 /*
  Encodes most data formats that are supported */