JMock, Hamcrest, Guava and Java8 lambdas collide in expressive ways

gistfile1.java

@Test
public void saves_results() throws IOException {
    ImmutableList<Associate> associates = ImmutableList.of(
        new Associate("id1", "fn1", "ln2"),
        new Associate("id2", "fn1", "ln2"));
        
    mockery.given((given) -> {
        given.oneOf(source).findAssociates("token");
        given.will(returnValue(associates.stream()));
    });
    mockery.when(() -> {
        assertThat(finder.findAssociates("token"), streamContaining(associates.toArray()));
    }).then((then) -> {
        then.oneOf(database).save(
            new AssociateList(Ids.NO_ID, OAuthAccount.STRAVA_PROD, "stravaId", associates));
    });
}