Collection Util isEmpty ImmutableList Java

CollectionUtil.java

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import java.util.List;

public class CollectionUtil {

    public static <T> List<T> getImmutableNonNullList(List<T> list) {
        return isEmpty(list) ? ImmutableList.<T>of() : ImmutableList.copyOf(list);
    }

    public static <T> boolean isEmpty(Iterable<?> iterable) {
        return iterable == null || Iterables.isEmpty(iterable);
    }
}

CollectionUtilTest.java

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import java.util.List;
import org.junit.Assert;
import org.junit.Test;

public class CollectionUtilTest {

    @Test
    public void testNullList() {
        List<String> expected = ImmutableList.<String>of();
        List<String> actual = CollectionUtil.getImmutableNonNullList(null);
        
        Assert.assertEquals("expecting empty immutable instance", expected, actual);
    }

    @Test
    public void testEmptyList() {
        List<String> expected = ImmutableList.<String>of();
        List<String> actual = CollectionUtil.getImmutableNonNullList(expected);
        
        Assert.assertEquals("expecting empty immutable instance", expected, actual);
    }
    
    @Test
    public void testMutableList() {
        List<String> mutableList = Lists.newArrayList("test1", "test2");
        ImmutableList<String> expected = ImmutableList.copyOf(mutableList);
        List<String> actual = CollectionUtil.getImmutableNonNullList(expected);
        Assert.assertEquals("expecting immutable list", expected, actual);
    }

    @Test
    public void testImmutableList() {
        ImmutableList<String> expected = ImmutableList.of("test1", "test2");
        List<String> actual = CollectionUtil.getImmutableNonNullList(expected);
        Assert.assertEquals("expecting immutable list", expected, actual);
    }

    /**
     * Test of isEmpty method, of class CollectionUtil.
     */
    @Test
    public void testIsEmpty() {
        Assert.assertTrue("should be true", CollectionUtil.isEmpty(null));
        Assert.assertTrue("should be true", CollectionUtil.isEmpty(ImmutableList.<String>of()));
        Assert.assertFalse("should be false", CollectionUtil.isEmpty(ImmutableList.<String>of("test")));
    }

}