support delay test

src/xs-test.cc

+#include <chrono>
 #include <cstdlib>
 #include <iostream>
+#include <string>
+#include <thread>
 
 #include <boost/filesystem.hpp>
 
@@ -10,10 +13,12 @@
 
 int main(int argc, char* argv[]) {
     if (argc < 2) {
-        std::cerr << "usage: " << argv[0] << " config" << std::endl;
+        std::cerr << "usage: " << argv[0] << " config [delay]" << std::endl;
         return EXIT_SUCCESS;
     }
 
+    const unsigned testDelay = (3 <= argc ? std::stoul(argv[2]) : 0u);
+
     namespace fs = boost::filesystem;
     const auto configFile = fs::absolute(argv[1]);
     if (!fs::is_regular_file(configFile)) {
@@ -22,5 +27,10 @@ int main(int argc, char* argv[]) {
     }
 
     xs::test::Tester tester{configFile};
+
+    std::this_thread::sleep_for(
+        std::chrono::seconds(testDelay)
+    );
+
     tester.run();
 }