java - 可选是否级联？

Question

级联返回Optional的模拟时会有什么行为？我的期望是the returned Optional object is also a mock .

但是，下面的测试表明情况并非如此:

@RunWith(JMockit.class)
public class CascadingTest {
    public static interface Foo {
        Optional<Bar> getOptionalBar();
    }

    public static interface Bar {
    }

    @Test
    public void cascadingOptional(@Mocked final Foo foo) {
        final Optional<Bar> opt = foo.getOptionalBar();
        assertThat(opt.get(), is(not(nullValue())));
    }
}

由于opt.get()抛出异常而进行的cascadingOptional测试:

java.util.NoSuchElementException: No value present
    at java.util.Optional.get(Optional.java:135)
    at jmockit.CascadingTest.cascadingOptional(CascadingTest.java:39)

这似乎表明 opt 不是一个模拟。顺便说一句，如何(直接)检查对象是否是 JMockit 模拟？

谢谢

JMockit v1.17

Answer 1

mocking API documentation根据模拟方法的返回类型指定默认返回的内容:

If no result is recorded for a given expectation, then all matching invocations will return the appropriate default value according to the method return type:

• Most java.lang types (String, Object, etc.): returns null.
• java.math types (BigDecimal, etc.): returns null.
• Primitive/wrapper types: returns the standard default value (false for boolean/Boolean, 0 for int/Integer, and so on).
• java.util.List, java.util.Collection, or java.lang.Iterable: returns Collections.EMPTY_LIST.
• java.util.Iterator or java.util.ListIterator: returns an empty iterator.
• java.util.Set: returns Collections.EMPTY_SET.
• java.util.SortedSet: returns an unmodifiable empty sorted set.
• java.util.Map: returns Collections.EMPTY_MAP.
• java.util.SortedMap: returns an unmodifiable empty sorted map.
• java.util.Optional: returns Optional.empty().
• Other reference types: returns a mocked instance through cascading.
• Array types: returns an array with zero elements (empty) in each dimension.