junit testing for user input using Scanner

Question

I have to test a method in a class which takes an input using Scanner class.

package com.math.calculator;

import java.util.Scanner;

public class InputOutpu         


        

Answer 1

You can write a clear test for the command line interface by using the TextFromStandardInputStream rule of the System Rules library.

public void MyTest {
  @Rule
  public final TextFromStandardInputStream systemInMock
    = emptyStandardInputStream();

  @Test
  public void shouldTakeUserInput() {
    systemInMock.provideLines("add 5", "another line");
    InputOutput inputOutput = new InputOutput();
    assertEquals("add 5", inputOutput.getInput());
  }
}