Is there a Hamcrest matcher to check that a Collection is neither empty nor null?

Question

Is there a Hamcrest matcher which checks that the argument is neither an empty Collection nor null?

I guess I could always use

both(notNullValue()).and(not(hasSize(0))

but I was wondering whether there is a simpler way and I missed it.

Answer 1

You can combine the IsCollectionWithSize and the OrderingComparison matcher:

@Test
public void test() throws Exception {
    Collection<String> collection = ...;
    assertThat(collection, hasSize(greaterThan(0)));
}

• For collection = null you get

  java.lang.AssertionError: 
  Expected: a collection with size a value greater than <0>
      but: was null
  

• For collection = Collections.emptyList() you get

  java.lang.AssertionError: 
  Expected: a collection with size a value greater than <0>
      but: collection size <0> was equal to <0>
  

• For collection = Collections.singletonList("Hello world") the test passes.

---

Edit:

Just noticed that the following approch is not working:

assertThat(collection, is(not(empty())));

The more i think about it the more i would recommend a slightly altered version of the statement written by the OP if you want to test explicitly for null.

assertThat(collection, both(not(empty())).and(notNullValue()));