@Test
public void testCreate_WithNullFunction() {

    final MultiLevelSource lonSource = new TestMultiLevelSource(10, 10);
    final MultiLevelSource latSource = new TestMultiLevelSource(10, 10);
    final LonLatFunction function = null;
    try {
        LonLatMultiLevelSource.create(lonSource, latSource, function, DataBuffer.TYPE_DOUBLE);
        fail();
    } catch (IllegalArgumentException ignored) {
    }
}