tests: Add one dummy test

...so that cmake has something to build.

Change-Id: I0b1747b51a3a000695ccf5769676035c696e24c5
diff --git a/tests/dummy.cpp b/tests/dummy.cpp
new file mode 100644
index 0000000..481c155
--- /dev/null
+++ b/tests/dummy.cpp
@@ -0,0 +1,13 @@
+/*
+ * Copyright (C) 2018 CESNET, https://photonics.cesnet.cz/
+ *
+ * Written by Jan Kundrát <jan.kundrat@cesnet.cz>
+ *
+*/
+
+#include "trompeloeil_catch.h"
+
+TEST_CASE("a do-nothing test sample")
+{
+    REQUIRE(1 == 1);
+}