Junit assert OR condition in my test case

You can use Hamcrest matchers to get a clearer error message here:

int i = 2;
assertThat(i, Matchers.either(Matchers.is(3)).or(Matchers.is(5))

or

int i = 2;
assertThat(i, Matchers.anyOf(Matchers.is(3),Matchers.is(5)));

This will more clearly explain:

Expected: (is <3> or is <5>)
     but: was <2>

showing exactly the expectation and the incorrect value that was provided.