@Test
public void testsGetHeadLinked() {
FunctionalList testList = new FunctionalLinkedList();
assertEquals("get Head on empty", ErrorMessage.EMPTY_STRUCTURE, testList.head().getError());
testList.add("zero");
testList.add("one");
testList.add("two");
assertEquals(
"get Head when not empty, no error", ErrorMessage.NO_ERROR, testList.head().getError());
assertEquals("get Head when not empty, correct item", "zero", testList.head().getReturnValue());
}
