Writing data to System.in

Question

In our application, we expect user input within a Thread as follows :

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

I want to pass that part in my unit test so that I can resume the thread to execute the rest of the code. How can I write something into System.in from junit?

Answer 1

What you want to do is use the method setIn() from System. This will let you pass data into System.in from junit.

Answer 2

Replace it for the duration of your test:

String data = "the text you want to send";
InputStream testInput = new ByteArrayInputStream( data.getBytes("UTF-8") );
InputStream old = System.in;
try {
    System.setIn( testInput );

    ...
} finally {
    System.setIn( old );
}