Added unit testing with Catch2 framework

src/tests.cpp

@@ -0,0 +1,13 @@
+#include "config.hpp"
+#include <catch2/catch_all.hpp>
+#include <string>
+
+TEST_CASE("Checking config file read", "[config]") {
+  const std::string FILE_NAME = "../config/config_example.toml";
+
+  Config config = get_config(FILE_NAME);
+
+  REQUIRE(config.contact.author == "author");
+  REQUIRE(config.contact.email == "email@example.com");
+  REQUIRE(config.contact.signal == "signal url");
+}