[FIXED] Junit Parameterized arrays

Issue

Is there any way to test cases with arrays and not integers? For example:

private int[] myArray;

public SortingTestNullCase(int[] arr){
    this.myArray=arr;
}

@Parameterized.Parameters
public static Collection testCases() {
    return Arrays.asList(new Integer[][] {
            {1,1,1},
            {2,2,2}
    });
}

I always get an error "java.lang.IllegalArgumentException: wrong number of arguments", because I am taking Integers in my constructor with Parameterized parameters, is there any way I can test inputs with arrays?

Solution

Your code has two problems:

1. You have to use the same type for your array, otherwise you will
   get IllegalArgumentException: argument type mismatch

2. Your test data creates only one parameter input by creating only one Integer[][] array.

Here is some code that should work for you

@RunWith(Parameterized.class)
public class PTest {

   private Integer[] myArray;

   public PTest(Integer[] array) {
      myArray = array;
   }

   @Parameters
   public static Collection testCases() {

      return Arrays.asList(new Integer[][] { { 1, 1, 1 } }, new Integer[][] { { 2, 2, 2 } });
   }

   @Test
   public void doTest() {

      System.out.println(Arrays.toString(myArray));
   }

}

Result looks like

[1, 1, 1]
[2, 2, 2]

Instead of using a constructor you could use the @Parameter annotation for your data member, which must be public then

@RunWith(Parameterized.class)
public class PTest {

   @Parameter
   public Integer[] myArray;

   @Parameters
   public static Collection testCases() {

      return Arrays.asList(new Integer[][] { { 1, 1, 1 } }, new Integer[][] { { 2, 2, 2 } });
   }

   @Test
   public void doTest() {

      System.out.println(Arrays.toString(myArray));
   }

}

Answered By - Michael Katt
Answer Checked By - Terry (JavaFixing Volunteer)