Why isn't the system() command working for me?

I'm new to c, so I'm probably stupid.

Here is somewhat my code:

#include <stdio.h>
#include <stdlib.h>

int main() {
  int input;
  setvbuf(stdout, NULL, _IONBF, 0);
  printf("Welcome to example");
  printf("\n" "Select an option." "\n" "1. ex1" "\n" "2. ex2" "\n");
  scanf("%d", &input);
  if (input == 1) {
    printf ("You selected ex1.");
    system("echo 'testing.'");
  }
  else if (input == 2) {
    printf ("You selected ex2.");
  }
  return 0;
}

If you're wondering, I'm running the exe in MSYS2 with ./a.exe

If I input 1, then it should execute the command echo. However, it does nothing.

How do I fix this?

Edit: Heres the output

You selected ex1.

And then the program ends. It could be because system uses command prompt (I'm having issues with command prompt...), so how do I switch it to use MSYS2 as the system terminal?