JUnit 4 compare Sets

You can assert that the two Sets are equal to one another, which invokes the Set equals() method.

public class SimpleTest {

    private Set<String> setA;
    private Set<String> setB;

    @Before
    public void setUp() {
        setA = new HashSet<String>();
        setA.add("Testing...");
        setB = new HashSet<String>();
        setB.add("Testing...");
    }

    @Test
    public void testEqualSets() {
        assertEquals( setA, setB );
    }
}

This @Test will pass if the two Sets are the same size and contain the same elements.

Apache commons to the rescue again.

assertTrue(CollectionUtils.isEqualCollection(coll1, coll2));

Works like a charm. I don't know why but I found that with collections the following assertEquals(coll1, coll2) doesn't always work. In the case where it failed for me I had two collections backed by Sets. Neither hamcrest nor junit would say the collections were equal even though I knew for sure that they were. Using CollectionUtils it works perfectly.

with hamcrest:

assertThat(s1, is(s2));

with plain assert:

assertEquals(s1, s2);

NB:t the equals() method of the concrete set class is used