java UT为Some&None

Posted 2021-05-07

public class OptionTest {
    private List<Option<String>> names = null;
    @Before
    public void setup() {
        names = new ArrayList<Option<String>>();
        names.add(new Some<String>("Dean"));
        names.add(new None<String>());
        names.add(new Some<String>("Wampler"));
    }
    @Test
    public void getOrElseUsesValueForSomeAndAlternativeForNone() {
        String[] expected = { "Dean", "Unknown!", "Wampler"};;
        System.out.println("*** Using getOrElse:");
        for (int i = 0; i < names.size(); i++) {
            Option<String> name = names.get(i);
            String value = name.getOrElse("Unknown!");
            System.out.println(name + ": " + value);
            assertEquals(expected[i], value);
        }
    }


    @Test
    public void hasNextWithGetUsesOnlyValuesForSomes() {
        String[] expected = { "Dean", null, "Wampler"};;
        System.out.println("*** Using hasValue:");
        for (int i = 0; i < names.size(); i++) {
            Option<String> name = names.get(i);
            if (name.hasValue()) {
                String value = name.get();
                System.out.println(name + ": " + value);
                assertEquals(expected[i], value);
            }
        }
    }
    static Option<String> wrap(String s) {
        if (s == null)
            return new None<String>();
        else
            return new Some<String>(s);
    }
    @Test
    public void exampleMethodReturningOption() {
        System.out.println("*** Method that Returns an Option:");
        Option<String> opt1 = wrap("hello!");
        System.out.println("hello! -> "+opt1);
        assertEquals(Some.class, opt1.getClass());
        assertEquals("hello!", opt1.get());
        Option<String> opt2 = wrap(null);
        System.out.println("null -> "+opt2);
        assertEquals(None.class, opt2.getClass());
        assertEquals("str", opt2.getOrElse("str"));
    }
}