only run termios test if stdin is a tty

src/Compat.cpp

@@ -24,6 +24,7 @@ void resetTermios(void) {
 }
 
 TEST_CASE("init and reset termios") {
+    if (isatty(STDIN_FILENO)) {
         struct termios original;
         tcgetattr(0, &original);
         SUBCASE("no echo") {
@@ -36,6 +37,7 @@ TEST_CASE("init and reset termios") {
         struct termios current;
         tcgetattr(0, &current);
         CHECK(std::memcmp(&original, &current, sizeof(struct termios)) == 0);
+    }
 }
 
 char getch_(int echo) {