Can assertEquals only be applicable for same data types?-CodePudding

Can AssertEquals be applied for different data typed input and outputs ?When I have applied AssertEquals to different data typed input and output,the AssertEquals gets striked off..and even the successful test case are not passing ?

What I meant by different data typed input and outputs means..Say example,Consider a program to check whether a number is even or odd.The input to this program is a number which is 'int' data type and output to this program is a 'String' datatype,which prints the number is "even" or "odd".

Here is the code

package BasicTesting;

import java.util.*;
class EvenOdd
{
    
  public static void main(String args[])
  {
    System.out.println("Enter any integer to check whether its odd or even...");
    Scanner ob = new Scanner(System.in);
    int i;
    
    i = ob.nextInt();
    OddEven(i);
    
  }
  public static void OddEven(int i) {
      if(i%2==0)
        {
            System.out.println("You entered an even number");
        }
        else
        {
            System.out.println("You entered an odd number");
        }
  }
}

This is the JUnit test case I have tried to written...but there are some errors in it because of the different data types. package BasicTesting;

import static org.junit.Assert.*;

import org.junit.Test;

public class EvenOddTest {

    @Test
    public static void test() {
        
        

        // TODO Auto-generated method stub
        EvenOdd a=new EvenOdd();
        //int res=a.OddEven(10);
        assertEquals("You entered an even number",a.OddEven(10));
        
    }

}

Please help me to write parameterized JUnit test case.Hope you will help.

CodePudding user response：

I'm afraid your test is nonsensical. You can't compare the result of a call to OddEven to anything. It is a void method. It doesn't return anything.

(Presumably the "different types" the compiler is talking about are String and void or Void. But void not really a type at all. Or at least, not in any useful sense.)

Unfortunately, a method whose sole observable action is to write to standard output is difficult to write a unit test for. You would need to use a mocking framework and mock System.out. (Or use System.setOut so replace standard output with some stream that allows you to capture the output.)

A better idea (and a better design) is to have your evenOdd method NOT write to standard output. Instead, have it return a boolean, and let the caller write the message ... or do something else with the result.

CodePudding user response：

If you're trying to compare different data types, like int with long something like this -

Assert.assertEquals(23.374f, 23.374d)

You can wrap the values in BigDecimal and compare like this -

float f = 23.374f;
double  d = 23.374d;
BigDecimal decimal_f = new BigDecimal(Float.toString(f));
BigDecimal decimal_d = new BigDecimal(Double.toString(d));
assertEquals(decimal_f,decimal_d);

Note - Usage of BigDecimal will also add some overhead.