java Mockito isA(Class<T> clazz) 如何解决类型安全问题？
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Mockito isA(Class<T> clazz) How to resolve type safety?
提问by Mike
in my test I have the following line:
在我的测试中，我有以下几行：
when(client.runTask(anyString(), anyString(), isA(Iterable.class)).thenReturn(...)
isA(Iterable.class)produces warning that it needs unchecked conversion to conform to Iterable<Integer>. What is syntax for that?
isA(Iterable.class)产生警告，它需要未经检查的转换才能符合Iterable<Integer>. 什么是语法？
isA(Iterable<Integer>.class)
isA((Iterable<Integer>)Iterable.class
do not work.
不工作。
Any suggestions?
有什么建议？
回答by Arend v. Reinersdorff
Mockito/Hamcrest and generic classes
Mockito/Hamcrest 和泛型类
Yes, this is a general problem with Mockito/Hamcrest. Generally using isA()with generic classes produces a warning.
是的，这是 Mockito/Hamcrest 的普遍问题。通常isA()与泛型类一起使用会产生警告。
There are predifined Mockito matchers for the most common generic classes: anyList(), anyMap(), anySet()and anyCollection().
有predifined匹配器的Mockito为最常用的通用类：anyList（） ，anyMap()，anySet()和anyCollection()。
Suggestions:
建议：
anyIterable() in Mockito 2.1.0
Mockito 2.1.0 中的 anyIterable()
Mockito 2.1.0 added a new anyIterable()method for matching Iterables:
Mockito 2.1.0 添加了一个新的anyIterable()方法来匹配可迭代对象：
when(client.runTask(anyString(), anyString(), anyIterable()).thenReturn(...)
Ignore in Eclipse
在 Eclipse 中忽略
If you just want to get rid of the warning in Eclipse. Option exists since Eclipse Indigo:
如果您只是想摆脱 Eclipse 中的警告。选项自Eclipse Indigo起就存在：
Window > Preferences > Java > Compiler > Errors/Warnings > Generic types > Ignore unavoidable generic type problems
窗口 > 首选项 > Java > 编译器 > 错误/警告 > 泛型类型 > 忽略不可避免的泛型类型问题
Quick Fix with @SuppressWarnings
使用@SuppressWarnings 快速修复
I suggest you do this if you have the problem only once. I personally don't remember ever needing an isA(Iterable.class).
如果您只遇到一次问题，我建议您这样做。我个人不记得曾经需要一个isA(Iterable.class).
As Daniel Pryden says, you can limit the @SuppressWarningsto a local variable or a helper method.
正如 Daniel Pryden 所说，您可以将 限制@SuppressWarnings为局部变量或辅助方法。
Use a generic isA() matcher with TypeToken
使用带有 TypeToken 的通用 isA() 匹配器
This solves the problem for good. But it has two disadvantages:
这很好地解决了问题。但它有两个缺点：
- The syntax is not too pretty and might confuse some people.
- You have an additional dependency on the library providing the
TypeTokenclass. Here I used the TypeToken class from Guava. There's also aTypeTokenclass in Gson and aGenericTypein JAX-RS.
- 语法不太漂亮，可能会让一些人感到困惑。
- 您对提供
TypeToken类的库有额外的依赖。这里我使用了来自 Guava的TypeToken 类。TypeToken在 Gson 中还有一个类，GenericType在 JAX-RS 中也有一个类。
Using the generic matcher:
使用通用匹配器：
import static com.arendvr.matchers.InstanceOfGeneric.isA;
import static org.mockito.ArgumentMatchers.argThat;
// ...
when(client.runTask(anyString(), anyString(), argThat(isA(new TypeToken<Iterable<Integer>>() {}))))
.thenReturn(...);
Generic matcher class:
通用匹配器类：
package com.arendvr.matchers;
import com.google.common.reflect.TypeToken;
import org.mockito.ArgumentMatcher;
public class InstanceOfGeneric<T> implements ArgumentMatcher<T> {
private final TypeToken<T> typeToken;
private InstanceOfGeneric(TypeToken<T> typeToken) {
this.typeToken = typeToken;
}
public static <T> InstanceOfGeneric<T> isA(TypeToken<T> typeToken) {
return new InstanceOfGeneric<>(typeToken);
}
@Override
public boolean matches(Object item) {
return item != null && typeToken.getRawType().isAssignableFrom(item.getClass());
}
}
回答by Daniel Pryden
Here's what I do:
这是我所做的：
// Cast from Class<Iterable> to Class<Iterable<Integer>> via the raw type.
// This is provably safe due to erasure, but will generate an unchecked warning
// nonetheless, which we suppress.
@SuppressWarnings("unchecked")
Class<Iterable<Integer>> klass
= (Class<Iterable<Integer>>) (Class) Iterable.class;
// later
isA(klass) // <- now this is typesafe
回答by Garrett Hall
You can add @SuppressWarnings("unchecked")above the statement. No other way but if it bothers you, you can move the cast to a helper method.
您可以@SuppressWarnings("unchecked")在语句上方添加。别无他法，但如果它打扰您，您可以将强制转换移动到辅助方法。
回答by gontard
There is no way to do this. To simplify, you can't initialize this variable without warning :
没有办法做到这一点。为简化起见，您不能在没有警告的情况下初始化此变量：
Class<Iterable<Integer>> iterableIntegerClass = ?
One solution might be to use the pseudo-typedef antipattern,
,you create and use an IntegerIterableinterface
一种解决方案可能是使用伪 typedef 反模式，您创建并使用IntegerIterable接口
interface IntegerIterable extends Iterable<Integer> {}
then
然后
isA(IntegerIterable.class)
will no more produce warning. But you will have to extend the class implementing Iterableto let them implements IntegerIterable:) For example :
将不再产生警告。但是您必须扩展实现类Iterable才能让它们实现IntegerIterable:) 例如：
public class IntegerArrayList extends ArrayList<Integer> implements IntegerIterable {}
Mmm tasty...
嗯好吃...
So, i will sugest you to consider to just paper over the cracks by adding to your method :
所以，我会建议你考虑通过添加到你的方法来掩盖裂缝：
@SuppressWarnings("unchecked")
