如何测试使用LocalDateTime.now()创建的日期 [英] How to test date created with LocalDateTime.now()

问题描述

我有这堂课

class MyObject {
    private LocalDateTime date;

    public LocalDateTime getDate() { return this.date; }

    public void myMethod() {
        this.date = LocalDateTime.now();
    }
}

如何测试日期设置正确?我不能模拟 now()，因为它是静态的，如果我在测试中使用LocalDateTime，则两个日期将不相同.

How can I test that the date is properly set? I cannot mock now() because it is static and if I used LocalDateTime in the test both dates won't be the same.

推荐答案

您可以在调用 myMethod()之前生成日期时间，并确保该日期在之前或等于到 getDate()返回的日期，类似这样:

You could generate a date time just before calling myMethod() and make sure that this date is before or equals to the date returned by getDate(), something like that:

@Test
public void testDate() {
    MyObject object = new MyObject();
    // Get the current date time 
    LocalDateTime time = LocalDateTime.now();
    // Affect the current date time to the field date
    object.myMethod();
    // Make sure that it is before or equals
    Assert.assertTrue(time.isBefore(object.getDate()) || time.isEqual(object.getDate()));
}

---

如果您不希望在类中添加耦合，则更好的方法可能是提供

---

If you don't care adding coupling to your class a better approach could be to provide a Supplier<LocalDateTime> to your class as next:

public class MyObject {
    private final Supplier<LocalDateTime> supplier;
    private LocalDateTime date;

    public MyObject() {
        this(LocalDateTime::now);
    }

    public MyObject(final Supplier<LocalDateTime> supplier) {
        this.supplier = supplier;
    }

    public LocalDateTime getDate() { return this.date; }

    public void myMethod() {
        this.date = supplier.get();
    }
}

通过这种方式，可以轻松创建 供应商 用于测试用例.

This way it will be easy to create a Supplier for testing purpose in your test case.

例如，测试用例可以是:

For example the test case could then be:

@Test
public void testDate() {
    LocalDateTime time = LocalDateTime.now();
    MyObject object = new MyObject(() -> time);
    object.myMethod();
    Assert.assertTrue(time.isEqual(object.getDate()));
}

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