How to compare two Streams in Java 8

Question

What would be a good way to compare two Stream instances in Java 8 and find out whether they have the same elements, specifically for purposes of unit testing?

What I've got now is:

@Test void testSomething() {   Stream<Integer> expected;   Stream<Integer> thingUnderTest;   // (...)   Assert.assertArrayEquals(expected.toArray(), thingUnderTest.toArray()); } 

or alternatively:

Assert.assertEquals(     expected.collect(Collectors.toList()),     thingUnderTest.collect(Collectors.toList())); 

But that means I'm constructing two collections and discarding them. It's not a performance issue, given the size of my test streams, but I'm wondering whether there's a canonical way to compare two streams.

Answer 1

static void assertStreamEquals(Stream<?> s1, Stream<?> s2) {     Iterator<?> iter1 = s1.iterator(), iter2 = s2.iterator();     while(iter1.hasNext() && iter2.hasNext())         assertEquals(iter1.next(), iter2.next());     assert !iter1.hasNext() && !iter2.hasNext(); }