Comparing arrays in JUnit assertions, concise built-in way?

Question

Use org.junit.Assert's method assertArrayEquals:

import org.junit.Assert;
...

Assert.assertArrayEquals( expectedResult, result );

If this method is not available, you may have accidentally imported the Assert class from junit.framework.

You can use Arrays.equals(..):

assertTrue(Arrays.equals(expectedResult, result));

I prefer to convert arrays to strings:

Assert.assertEquals(
                Arrays.toString(values),
                Arrays.toString(new int[] { 7, 8, 9, 3 }));

this way I can see clearly where wrong values are. This works effectively only for small sized arrays, but I rarely use arrays with more items than 7 in my unit tests.

This method works for primitive types and for other types when overload of toString returns all essential information.

Assert.assertArrayEquals("message", expectedResult, result)

Using junit4 and Hamcrest you get a concise method of comparing arrays. It also gives details of where the error is in the failure trace.

import static org.junit.Assert.*
import static org.hamcrest.CoreMatchers.*;

//...

assertThat(result, is(new int[] {56, 100, 2000}));

Failure Trace output:

java.lang.AssertionError: 
   Expected: is [<56>, <100>, <2000>]
   but: was [<55>, <100>, <2000>]

I know the question is for JUnit4, but if you happen to be stuck at JUnit3, you could create a short utility function like that:

private void assertArrayEquals(Object[] esperado, Object[] real) {
    assertEquals(Arrays.asList(esperado), Arrays.asList(real));     
}

In JUnit3, this is better than directly comparing the arrays, since it will detail exactly which elements are different.

JUnit 5 we can just import Assertions and use Assertions.assertArrayEquals method

import org.junit.jupiter.api.Assertions;

Assertions.assertArrayEquals(resultArray,actualResult);