1 package org.hamcrest.collection; 2 3 import org.hamcrest.Description; 4 import org.hamcrest.Matcher; 5 import org.hamcrest.TypeSafeMatcher; 6 7 import java.util.Collection; 8 9 /** 10 * Tests if collection is empty. 11 */ 12 public class IsEmptyCollection<E> extends TypeSafeMatcher<Collection<? extends E>> { 13 14 @Override matchesSafely(Collection<? extends E> item)15 public boolean matchesSafely(Collection<? extends E> item) { 16 return item.isEmpty(); 17 } 18 19 @Override describeMismatchSafely(Collection<? extends E> item, Description mismatchDescription)20 public void describeMismatchSafely(Collection<? extends E> item, Description mismatchDescription) { 21 mismatchDescription.appendValue(item); 22 } 23 24 @Override describeTo(Description description)25 public void describeTo(Description description) { 26 description.appendText("an empty collection"); 27 } 28 29 /** 30 * Creates a matcher for {@link java.util.Collection}s matching examined collections whose <code>isEmpty</code> 31 * method returns <code>true</code>. 32 * For example: 33 * <pre>assertThat(new ArrayList<String>(), is(empty()))</pre> 34 * 35 */ empty()36 public static <E> Matcher<Collection<? extends E>> empty() { 37 return new IsEmptyCollection<E>(); 38 } 39 40 /** 41 * Creates a matcher for {@link java.util.Collection}s matching examined collections whose <code>isEmpty</code> 42 * method returns <code>true</code>. 43 * For example: 44 * <pre>assertThat(new ArrayList<String>(), is(emptyCollectionOf(String.class)))</pre> 45 * 46 * @param unusedToForceReturnType 47 * the type of the collection's content 48 */ 49 @SuppressWarnings({"unchecked", "UnusedParameters"}) emptyCollectionOf(Class<E> unusedToForceReturnType)50 public static <E> Matcher<Collection<E>> emptyCollectionOf(Class<E> unusedToForceReturnType) { 51 return (Matcher)empty(); 52 } 53 } 54