message: Display the demos UI if argv[1] isn't a valid test
diff: @@ -328,14 +328,28 @@ Usage: %s Test_Name [test_options]
  return 1;
  }
  - std::string testchoice;
  + // Check if the first arg is a valid test name. If it isn't,
  + // allow the UI to appear, so that flags can be used with the UI
  + bool validTestArg = false;
  + if(argc >= 2)
  + {
  + for(const TestMetadata &test : tests)
  + {
  + if(!strcmp(test.Name, argv[1]))
  + {
  + validTestArg = true;
  + break;
  + }
  + }
  + }
  + std::string testchoice;
  if(tests.size() == 1)
  {
  // if there's only one test we've probably hardcoded this for a repro. Launch it
  testchoice = tests[0].Name;
  }
  - else if(argc >= 2)
  + else if(validTestArg)
  {
  testchoice = argv[1];
  }
  