JUnit asserting two Strings whether they're equal or not

Question

So I looked up this question and tried it, but with no success.

My code should be testing if the method is correctly outputing the text onto the console by reading it back in using Streams.

    ByteArrayOutputStream outStream = new ByteArrayOutputStream();
    PrintStream myStream = new PrintStream(outStream);
    System.setOut(myStream);
    o.doSomething(); //printing out Hi
    System.out.flush();
    System.setOut(savedOldStream);//setting it back to System.out
    assertEquals(outStream.toString(),"Hi");

but everytime I run JUnit it fails. I also tried: assertTrue(outStream.toString().equals("Hi")); but this didn't work either.

This is the doSomething() method:

public void doSomething () {
    System.out.println("Hi");
}

Swellfish

What do you mean by "didn't work"? What actually happens? Are you getting any errors or just a failed assertion? – Mikemikel

There is no need to re-assign the System.out to test this. You can pass the ByteArrayOutputStream to the doSomething() method. – Hera

Answer 1

PrintStream#println(String str) appends a newline at the end of the string. Therefore, your assertion should trim down the additional line:

assertEquals(outStream.toString().trim(),"Hi");

Hera

Writing to System.out will not write anything in the ByteArrayOutputStream. – Ambrose

Thank you very much! SO using System.out.print would also fix the problem? – Swellfish

@Ambrose The OP has re-assigned System.out. – Hera

@Swellfish Yes using print would avoid the newline. – Hera

Agree. For this case, the OP could do as you suggested: passing the output stream as param. – Hera