单元测试Java 8谓词

Question

我有一个这样的Java8谓词。我如何为此编写单元测试？

 Predicate<DTO> isDone = (dtO) ->
                (!dto.isFinished() &&
                !dto.isCompleted());

谢谢

Answer 1

我会这样测试它：

private final Predicate<DTO> isDone = (dto) ->
        (!dto.isFinished() && !dto.isCompleted());

@Test
public void a() throws Exception {
    // given
    DTO dto = new DTO(true, true);

    // when
    boolean result = isDone.test(dto);

    // then
    assertThat(result).isFalse();
}

@Test
public void s() throws Exception {
    // given
    DTO dto = new DTO(true, false);

    // when
    boolean result = isDone.test(dto);

    // then
    assertThat(result).isFalse();
}

@Test
public void d() throws Exception {
    // given
    DTO dto = new DTO(false, true);

    // when
    boolean result = isDone.test(dto);

    // then
    assertThat(result).isFalse();
}

@Test
public void f() throws Exception {
    // given
    DTO dto = new DTO(false, false);

    // when
    boolean result = isDone.test(dto);

    // then
    assertThat(result).isTrue();
}

@AllArgsConstructor
public static class DTO {
    private final boolean isFinished;
    private final boolean isCompleted;

    public boolean isFinished() {
        return isFinished;
    }

    public boolean isCompleted() {
        return isCompleted;
    }
}

将测试命名为：should_be_done_when_it_is_both_finished_and_completed，而不是a、s和f。

我认为DTO只是一个值对象，所以我宁愿创建真实的实例，而不是使用模拟。

Answer 2

如果您有对谓词的引用(就像在您的示例中一样)，那么我认为没有问题。以下是Mockito/JUnit的简单示例：

@Mock
private DTO mockDTO;

@Test
public void testIsDone_Finished_NotComplete()
{
    when(mockDTO.isFinished()).thenReturn(true);
    when(mockDTO.isCompleted()).thenReturn(false);

    boolean expected = false;
    boolean actual = isDone.test(mockDTO);

    Assert.assertEquals(expected, actual);
}