Testing Programs that use command line input

Question

Hi,
I've written a program that takes values the user enters from the Standard Input (i.e. Dos/UNIX prompt) using the usual buffered reader. I now want to automate testing of this program using a second Java class.
What is the best way to pass values from the test harness into the program, when it is expecting them from the Standard Input?
hope someone can help!
Cheers

Answer 1

You can also create a new java process with the class you want to test.
String commandToTest[] = {
"java", "your.class", ...
Process process = Runtime.getRuntime().exec( commandToTest );
InputStream input = process.getInputStream();
OutputStream output = process.getOutputStream();
// and then send some input to your sub-process
//          read the outputIn the same spirit, you can also work with two threads:
- the first thread reassigns System.in, out and err
spawns a new Thread that will call your.class.main(...)
- the first thread sends some input to the new "System.in"
reads the output from the new "System.out"