Fredriks anteckningar

public class EmptyMatcher extends TypeSafeMatcher&lt;Collection < ?>> {
 
    @Override
    public boolean matchesSafely(Collection< ?> c) {
        return c.isEmpty();
    }
 
    public void describeTo(Description desc) {
        desc.appendText("empty");
    }
 
    @Factory
    public static lt;T> Matcher< ? super Collection<?>> isEmpty() {
        return new EmptyMatcher();
    }
}

@Test
public void filteringAnEmptyListReturnsAnEmptyList() {
    List anEmptyList = new ArrayList();
    List result = testee.filter(emptyList());
    assertThat(result, isEmpty());
    // men helst: assertThat(result).isEmpty();
}