Cyclops Data Structure: Immutability Test

ImmutabilityTest.java

public class ImmutabilityTest {

    private String a = "Tom";
    private String b = "Marc";
    private String c = "Lucy";
    private String d = "Bert";

    @Test
    public void givenUsingJava8List_whenListIsCreated_thenListIsMutable() {
        List<String> java8MutableList = new ArrayList<>(Arrays.asList(a, b, c));
        java8MutableList.add(d);
        assertThat(java8MutableList).contains(d);
    }

    @Test
    public void givenUsingListX_whenListIsCreated_thenListXIsMutable() {
        ListX<String> list = ListX.of(a, b, c);
        list.add(d);
        assertThat(list).contains(d);
        assertThat(list).isInstanceOf(List.class).isInstanceOf(LazyCollectionX.class);
    }

    @Test
    public void givenUsingCyclopsVector_whenVectorIsCreated_thenVectorIsImmutable() {
        Vector<String> vector = Vector.of(a, b, c);
        assertThat(vector).isInstanceOf(ImmutableList.class);
    }

    @Test
    public void givenUsingCyclopsVectorX_whenVectorIsCreated_thenVectorIsPersistentAndLazy() {
        VectorX<String> vectorLazy = VectorX.of(a, b, c);
        assertThat(vectorLazy).isInstanceOf(PersistentList.class).isInstanceOf(LazyCollectionX.class);
    }

    @Test
    public void givenUsingJava8List_whenUnmodifiableListIsCreated_thenListIsImmutable() {
        List<String> java8List = new ArrayList<>(Arrays.asList(a, b, c));
        List<String> unmodifiableList = Collections.unmodifiableList(java8List);
        ThrowingCallable throwingCallable = () -> unmodifiableList.add(d);
        assertThatExceptionOfType(UnsupportedOperationException.class).isThrownBy(throwingCallable);
    }

    @Test
    public void givenUsingJava9List_whenListIsCreated_thenListIsImmutable() {
        List<String> java9List = List.of(a, b, c);
        ThrowingCallable throwingCallable = () -> java9List.add(d);
        assertThatExceptionOfType(UnsupportedOperationException.class).isThrownBy(throwingCallable);
    }
}