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javaarraysjunitassertions
mBria
mBria

Reputation: 2562

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

Is there a concise, built-in way to do equals assertions on two like-typed arrays in JUnit? By default (at least in JUnit 4) it seems to do an instance compare on the array object itself.

EG, doesn't work:

int[] expectedResult = new int[] { 116800,  116800 };
int[] result = new GraphixMask().sortedAreas(rectangles);
assertEquals(expectedResult, result);

Of course, I can do it manually with:

assertEquals(expectedResult.length, result.length);
for (int i = 0; i < expectedResult.length; i++)
    assertEquals("mismatch at " + i, expectedResult[i], result[i]);

..but is there a better way?

Upvotes: 233

Views: 213568

Answers (8)

Pravanjan
Pravanjan

Reputation: 1006

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

import org.junit.jupiter.api.Assertions;

Assertions.assertArrayEquals(resultArray,actualResult);

Upvotes: 19

Ankur Agarwal
Ankur Agarwal

Reputation: 24758

Class Assertions in org.junit.jupiter.api

Use:

public static void assertArrayEquals(int[] expected,
                                     int[] actual)

Upvotes: 1

winstanr
winstanr

Reputation: 51

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>]

Upvotes: 5

csharpfolk
csharpfolk

Reputation: 4280

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.

Upvotes: 22

Haroldo_OK
Haroldo_OK

Reputation: 7230

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.

Upvotes: 4

Andy Thomas
Andy Thomas

Reputation: 86401

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.

Upvotes: 420

Michael Brewer-Davis
Michael Brewer-Davis

Reputation: 14276

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

Upvotes: 18

Bozho
Bozho

Reputation: 597076

You can use Arrays.equals(..):

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

Upvotes: 46

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