assertEquals doesn't work for sets

TestNG Version

7.1.0

Expected behavior

assertEquals yields true if called with two sets that contain the same elements, even if they are defined as Collection.

Actual behavior

Depending on the type of set and the type of objects they contain assertEquals might work well or fail because it relies on iterators to compare the two sets and in the case of sets the iteration order is not guaranteed. This behavior is is most evident on LinkedHashSets but also appears on HashSets depending on the type of objects they contain. I suspect it works well with TreeSets, which have a predictable iteration order.

Is the issue reproductible on runner?

• Shell
• Maven
• Gradle
• Ant
• Eclipse
• IntelliJ
• NetBeans

Test case sample

Test case excerpt (full test in attachment):

    @Test
    public void assertEqualsWorksOnLinkedHashSets() {
        final Collection<Integer> oneSet = new LinkedHashSet<>();
        oneSet.add(1);
        oneSet.add(2);
        final Collection<Integer> anotherSet = new LinkedHashSet<>();
        anotherSet.add(2);
        anotherSet.add(1);
        assertTrue(oneSet.equals(anotherSet)); //passes
        assertEquals(oneSet, anotherSet); //fails
    }

AssertEqualsOnSetsTest.zip

[mchintoanu]

I believe the contract of assertEquals is broken as long as it doesn’t return the same result as equals. And I have just thought of a simpler, cleaner solution than the one I proposed initially:

    if (actual.equals(expected)) {
      return;
    }
    //rest of assertEquals(Collection, Collection, String) implementation

I’ll check out the project and try to create a pull request if I have some spare time in the following days.

[amitbhoraniya]

@mchintoanu - You are using an instance of LinkedHashSet, which means you are expecting that order should be maintained.

assertEquals method with Collection argument expects that order also should be same. If you don’t wont to maintain the order then use HashSet instead of LinkedHashSet . Same method will work for you.

final Collection<Integer> oneSet = new HashSet<>();
oneSet.add(1);
oneSet.add(2);
final Collection<Integer> anotherSet = new HashSet<>();
anotherSet.add(2);
anotherSet.add(1);
Assert.assertTrue(oneSet.equals(anotherSet)); //passes
Assert.assertEquals(oneSet, anotherSet); //passes