groovy – 使用metaClass的Mock Gradle project.exec {…}

Project proj = ProjectBuilder.builder().build()

proj.MetaClass.exec = { Closure obj ->
    println 'mock EXEC'
}

proj.exec {
    executable 'echo'
    args 'PROjeCT EXEC'
}
// prints 'PROjeCT EXEC' instead of the 'mock EXEC' I expected

Project proj = ProjectBuilder.builder().build()

proj.MetaClass.othername = { Closure obj ->
    println 'mock EXEC'
}

proj.othername {
    executable 'echo'
    args 'PROjeCT EXEC'
}
// prints 'mock EXEC' as expected

在Groovy中,使用MetaClass替换接口中定义的方法已被破坏.在这种情况下,exec方法在Project类中定义,它是一个接口.从 GROOVY-3493(最初在2009年报道)：

"CAnnot override methods via Metaclass that are part of an interface implementation"

替代方法

invokeMethod拦截所有方法并且可以工作.这有点矫枉过正,但确实有效.当方法名称与exec匹配时,它会将调用转移到mySpecialInstance对象.否则它将传递给委托,即现有方法.感谢invokeMethod delegation和Logging All Methods对此的输入.

// This intercepts all methods,stubbing out exec and passing through all other invokes
this.project.MetaClass.invokeMethod = { String name,args ->
    if (name == 'exec') {
        // Call special instance to track verifications
        mySpecialInstance.exec((ClosurE) args.first())
    } else {
        // This calls the delegate without causing infinite recursion
        @L_326_5@method @L_326_5@method = delegate.class.MetaClass.get@L_326_5@method(name,args)
        return @L_326_5@method?.invoke(delegate,args)
    }
}

这很有效,除了你可能会看到关于“错误的参数数量”或“无法在Null对象上调用方法xxxxx”的异常.问题是上面的代码不处理方法参数的强制转换.对于project.files(Object … paths),invokeMethod的args应该是[[‘path1′,’path2’]]的形式.但是,在某些情况下,调用文件(null)或文件(),因此invokeMethod的args分别为[null]和[],因为它预期[[]]失败.产生上述错误.

以下代码仅解决了文件方法的问题,但这对我的单元测试来说已经足够了.我仍然想找到一种更好的强制类型或更换单一方法的方法.

// As above but handle coercing of the files parameter types
this.project.MetaClass.invokeMethod = { String name,args ->
    if (name == 'exec') {
        // Call special instance to track verifications
        mySpecialInstance.exec((ClosurE) args.first())
    } else {
        // This calls the delegate without causing infinite recursion
        // https://stackoverflow.com/a/10126006/1509221
        @L_326_5@method @L_326_5@method = delegate.class.MetaClass.get@L_326_5@method(name,args)
        logInvokeMethod(name,args,@L_326_5@method)

        // Special case 'files' method which can throw exceptions
        if (name == 'files') {
            // Coerce the arguments to match the signature of Project.files(Object... paths)
            // TODO: is there a way to do this automatically,e.g. coerceArgumentsToClasses?
            assert 0 == args.size() || 1 == args.size()

            if (args.size() == 0 ||  // files()
                args.first() == null) {  // files(null)
                return @L_326_5@method?.invoke(delegate,[[] as Object[]] as Object[])
            } else {
                // files(ArrayList) possibly,so cast ArrayList to Object[]
                return @L_326_5@method?.invoke(delegate,[(Object[]) args.first()] as Object[])
            }
        } else {
            // Normal pass through 
            return @L_326_5@method?.invoke(delegate,args)
        }
    }
}