Does assertEquals(Object o1, Object o2) uses the equals method

Question

In other words, does assertEquals works with a class that overrides equals

Answer 1

yes - TestNG overrides equals -

static public void assertEquals(Object actual, Object expected, String message) {
    if((expected == null) && (actual == null)) {
      return;
    }
    if(expected != null) {
      if (expected.getClass().isArray()) {
        assertArrayEquals(actual, expected, message);
        return;
      } else if (expected.equals(actual)) {
        return;
      }
    }
    failNotEquals(actual, expected, message);
  }

Answer 2

Yes it does.

Object m = new Object() {

    @Override
    public boolean equals(Object obj) {
        System.out.println("proof!");
        return super.equals(obj);
    }
};
Assert.assertEquals(m, m);

Answer 3

From the source code of the assertEquals method that you can find on the Junit GitHub Repo:

/**
 * Asserts that two objects are equal. If they are not
 * an AssertionFailedError is thrown with the given message.
 */
static public void assertEquals(String message, Object expected, Object actual) {
    if (expected == null && actual == null) {
        return;
    }
    if (expected != null && expected.equals(actual)) {
        return;
    }
    failNotEquals(message, expected, actual);
}

You can see that Junit is using the .equals() method.

Edit:

The code snippet is coming from a deprecated version of Junit.

You can read about the source of the 'new' Junit here. The idea is pretty much the same, the .equals() method is also used.

Answer 4

Yes, it calls equals and there is a separate method, assertSame, that uses ==. Just to clear things up, assertEquals works with any object since all objects declare equals.

Answer 5

does assertEquals works with a class that overrides equals?

Yes, assertEquals() invokes the overridden equals() if the class has one.

Answer 6

JUnit is opensource, so you could have looked it up yourself in the source: https://github.com/junit-team/junit4/blob/master/src/main/java/org/junit/Assert.java

static public void assertEquals(String message, Object expected,
        Object actual) {
    if (equalsRegardingNull(expected, actual)) {
        return;
    } else if (expected instanceof String && actual instanceof String) {
        String cleanMessage = message == null ? "" : message;
        throw new ComparisonFailure(cleanMessage, (String) expected,
                (String) actual);
    } else {
        failNotEquals(message, expected, actual);
    }
}

private static boolean equalsRegardingNull(Object expected, Object actual) {
    if (expected == null) {
        return actual == null;
    }

    return isEquals(expected, actual);
}

private static boolean isEquals(Object expected, Object actual) {
    return expected.equals(actual);
}

So as you can see it uses equals. If you want to compare identity, you use assertSame.