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Core API and libraries of hamcrest matcher framework.

There is a newer version: 3.0

package org.hamcrest.collection;

import org.hamcrest.Description;
import org.hamcrest.Matcher;
import org.hamcrest.TypeSafeMatcher;

import java.util.Collection;

/**
 * Tests if collection is empty.
 */
public class IsEmptyCollection extends TypeSafeMatcher> {

    @Override
    public boolean matchesSafely(Collection item) {
        return item.isEmpty();
    }

    @Override
    public void describeMismatchSafely(Collection item, Description mismatchDescription) {
      mismatchDescription.appendValue(item);
    }

    @Override
    public void describeTo(Description description) {
        description.appendText("an empty collection");
    }

    /**
     * Creates a matcher for {@link java.util.Collection}s matching examined collections whose isEmpty
     * method returns true.
     * For example:
     * assertThat(new ArrayList<String>(), is(empty()))
     *
     * @param 
     *     the matcher type.
     * @return The matcher.
     */
    public static  Matcher> empty() {
        return new IsEmptyCollection<>();
    }

    /**
     * Creates a matcher for {@link java.util.Collection}s matching examined collections whose isEmpty
     * method returns true.
     * For example:
     * assertThat(new ArrayList<String>(), is(emptyCollectionOf(String.class)))
     *
     * @param 
     *     the matcher type.
     * @param unusedToForceReturnType
     *     the type of the collection's content
     * @return The matcher.
     */
    @SuppressWarnings({"unchecked", "UnusedParameters"})
    public static  Matcher> emptyCollectionOf(Class unusedToForceReturnType) {
      return (Matcher)empty();
    }

}