在类的所有实例方法中隐式使用 Groovy Category [英] Use Groovy Category implicitly in all instance methods of class

问题描述

我有一个简单的 Groovy 类别类，它向 String 实例添加方法:

I have simple Groovy category class which adds method to String instances:

final class SampleCategory {

    static String withBraces(String self) {
        "($self)"
    }

}

我想在我的单元测试中使用这个类别(例如).它看起来像这样:

I want to use this category in my unit tests (for example). It looks like this:

class MyTest {
    @Test
    void shouldDoThis() {
        use (SampleCategory) {
            assert 'this'.withBraces() == '(this)'
        }
    }

    @Test
    void shouldDoThat() {
        use (SampleCategory) {
            assert 'that'.withBraces() == '(that)'
        }
    }
}

然而，我想要实现的是能够指定在 MyTest 的每个实例方法的范围内使用类别 SampleCategory 所以我不t 必须在每个方法中指定 use(SampleCategory) { ... }.

What I'd like to achieve, however, is ability to specify that category SampleCategory is used in scope of each and every instance method of MyTest so I don't have to specify use(SampleCategory) { ... } in every method.

有可能吗?

推荐答案

您可以使用 mixin 将类别直接应用于 String 的元类.为元类分配 null 以将其重置为常规默认值.例如:

You can use mixin to apply the category directly to String's metaClass. Assign null to the metaClass to reset it to groovy defaults. For example:

@Before void setUp() { 
    String.mixin(SampleCategory)
}

@After void tearDown() {
    String.metaClass = null
}

@Test
void shouldDoThat() {
    assert 'that'.withBraces() == '(that)'
}

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