Spock spy-在函数（Java）中使用的间谍类

Question

How can I spy for the Class File in anthoer function in class?
Works for the test when I use new File in the test but not in my class.

public class Clazz {
    public void fun(String path) {
        File file = new File(path);
        if (!file.exists()) {
            throw new FileNotFoundException();
        }
    }
}


//Spock-test
class test extends Specification {
    given:
    GroovySpy(File, global: true, useObjenesis: true)
    def mockFile = Mock(File) {
      exists() >> true
    }
    new File(path) >> {mockFile}

    when:
    Clazz.fun("test.file")

    then:
    ...
    ...
}

Answer 1

From official spock docs about Spy :

Think twice before using this feature. It might be better to change the design of the code under specification.

http://spockframework.org/spock/docs/1.0/interaction_based_testing.html

And there are no reason to use spy object in test like that. If you don't like to redesign code, you can always use groovy metaprogramming:

File.metaClass.exists = {true}