Java Mockito何时返回创建对象

Question

我试图测试一个计算年龄的类。计算年龄的方法是这样的：

public static int getAge(LocalDate birthdate) { 
    LocalDate today = new LocalDate(); 
    Period period = new Period(birthdate, today, PeriodType.yearMonthDay()); 
    return period.getYears(); 
} 

因为我想了JUnit是时间无关我想today变量始终是2016年1月1日，为了做到这一点，我试图去了Mockito.when路线，但我遇到了麻烦。

我第一次有这样的：

public class CalculatorTest { 

    @Before 
    public void setUp() throws Exception { 
     LocalDate today = new LocalDate(2016,1,1); 

     Mockito.when(new LocalDate()).thenReturn(today); 
    } 
} 

但是到我得到这个错误：

org.mockito.exceptions.misusing.MissingMethodInvocationException: 
when() requires an argument which has to be 'a method call on a mock'. 
For example: 
    when(mock.getArticles()).thenReturn(articles); 

Also, this error might show up because: 
1. you stub either of: final/private/equals()/hashCode() methods. 
    Those methods *cannot* be stubbed/verified. 
    Mocking methods declared on non-public parent classes is not supported. 
2. inside when() you don't call method on mock but on some other object. 

于是我试图让计算器类中的方法返回当前的日期，像这样：

public static LocalDate getCurrentDate() { 
    return new LocalDate(); 
} 

public static int getAge(LocalDate birthdate) { 
    LocalDate today = getCurrentDate(); 
    Period period = new Period(birthdate, today, PeriodType.yearMonthDay()); 
    return period.getYears(); 
} 

，这样我可以做到这一点：

public class CalculatorTest { 

    @Before 
    public void setUp() throws Exception { 
     CalculatorTest mock = Mockito.mock(CalculatorTest.class); 
     LocalDate today = new LocalDate(2016,1,1); 

     Mockito.when(mock.getCurrentDate()).thenReturn(today); 
    } 
} 

但是，我得到了完全相同的问题。那么，有关如何在触发年龄计算时返回预定义的本地对象的任何想法？

Answer 1

而不是嘲笑，我建议使用乔达的DateTimeUtils来“冻结”时间。您还需要在应用程序代码中使用org.joda.time.LocalDate而不是java.time.LocalDate。

public class CalculatorTest { 

    @Before 
    public void setUp() throws Exception { 
     DateTimeUtils.setCurrentMillisFixed(new LocalDate(2016,1,1).toDateTimeAtStartOfDay().getMillis()); 
    } 

    @After 
    public void tearDown() { 
     DateTimeUtils.setCurrentMillisSystem(); 
    } 
} 

对于纯Java，可以考虑一些方法描述here，具体地，注入Clock或使用PowerMock。

注入Clock与Joda示例非常相似;你只需要保持自己的静态Clock。您的应用程序代码应该是这样的：

static Clock appClock = Clock.systemDefaultZone(); 

public static int getAge(LocalDate birthdate) { 
    LocalDate today = LocalDate.now(appClock); 
    Period period = new Period(birthdate, today, PeriodType.yearMonthDay()); 
    return period.getYears(); 
} 

并且测试将冻结这样的时候：

public class CalculatorTest { 

    @Before 
    public void setUp() { 
     appClock = Clock.fixed(LocalDate(2016,1,1).toDateTimeAtStartOfDay(), ZoneId.systemDefault()); 
    } 

    @After 
    public void tearDown() { 
     appClock = Clock.systemDefaultZone(); 
    } 
} 

Answer 2

我八方通用我自己的TimeFactory来检索我的应用程序的currentdate。这样我可以灵活地操作它（在JUnit测试期间）。这就是TimeFactory样子：

public final class TimeFactory { 

    static int offsetAmount = 0; 
    static TemporalUnit offsetUnit = ChronoUnit.MILLIS; 

    public static LocalDateTime getLocalDateTimeNow() { 
     return LocalDateTime.now().plus(offsetAmount, offsetUnit); 
    } 

    public static void reset() { 
     offsetAmount = 0; 
    } 

    public static void travelToPast(int amount, TemporalUnit unit) { 
     offsetAmount = amount * -1; 
     offsetUnit = unit; 
    } 

    public static void travelToFuture(int amount, TemporalUnit unit) { 
     offsetAmount = amount; 
     offsetUnit = unit; 
    } 
} 

使用这个TimeFactory我可以很容易做到时间旅行：

// start test 
TimeFactory.travelToPast(10, ChronoUnit.HOURS); 
// continue tests 
TimeFactory.reset(); 
// check that things have happend in the past. 

可以扩大这个代码来解决的时间。

Answer 3

我建议你欺骗到测试方法：

public static int getAge(LocalDate currDate, LocalDate birthdate) { 
    Period period = new Period(birthdate, currDate, PeriodType.yearMonthDay()); 
    return period.getYears(); 
} 

public static int getAge(LocalDate birthdate) { 
    return getAge(new LocalDate(), birthdate); 
}