[FIXED] My junit tests keep failing even though code is correct

Issue

I've just started to learn java coding in college a month back. Here I'm just making a very simple program to reverse a string entered by the user.

For eg- if I enter "apple" it should return "elppa". However, my JUnit tests keep failing here. I tried using the debugger on the JUnit, but it just keeps throwing an exception java.lang.reflect.InvocationTargetException.

I would really appreciate it if anyone here could help me fix this. Thanks in advance!! (Also please ignore my silly variable and class names, I was just messing around a bit)

public String word;

public wechillin (String wordin) {
    word= wordin;
}

public void Reverse() {
    String newword= "";
    for (int i= word.length()-1; i>=0; i--) {
        newword+= word.charAt(i);
    } 
    word= newword;
}

Test:

    @Test
    public void testReverse() {
        wechillin all = new wechillin("apple"); 
        all.Reverse();
        assertTrue(all.toString.equals("elppa"));
    }

Solution

1. First of all you can override toString method to return only word value.

@Override public String toString() { return word; }

2. I would recommend you to create getter for the value word and check this value in the unit test. Please see the following example:

    public class wechillin {
   
      public String word;
   
      public wechillin (String wordin) {
        word= wordin;
      }
   
      public void Reverse() {
        String newword= "";
        for (int i= word.length()-1; i>=0; i--) {
          newword+= word.charAt(i);
        }
        word= newword;
      }
   
      public String getWord() {
        return word;
      }
    }
   

And unit test:

class wechillinTest {

  @Test
  void reverse() {
    wechillin all = new wechillin("apple");
    all.Reverse();
    assertTrue(all.getWord().equals("elppa"));
  }
}

Answered By - Andrian Soluk