[SOLVED] How to properly document S4 "[" and “[<-“ methods using roxygen?

How to properly document S4 "[" and “[<-“ methods using roxygen?

Below I posted a mini example in which I want do write documentation for an “[“ method for a S4 class. Does someone know how to properly document a method for the generic "[" using roxygen and S4?
I get a warning when checking the package after building (see below).

#' An S4 class that stores a string.
#' @slot a contains a string
#' @export
setClass("testClass", 
         representation(a="character"))

#' extract method for testClass
#'
#' @docType methods
#' @rdname extract-methods
setMethod("[", signature(x = "testClass", i = "ANY", j="ANY"),
         function (x, i, j, ..., drop){
             print("void function")
         }
)

Excerpt from package check:

* checking for missing documentation entries ... WARNING
Undocumented S4 methods:
  generic '[' and siglist 'testClass'
All user-level objects in a package (including S4 classes and methods)
should have documentation entries.
See the chapter 'Writing R documentation files' in manual 'Writing R Extensions'.

Solution

As of roxygen2 >3.0.0, you no longer need work arounds and only need:

#' Extract parts of testClass.
#'
setMethod("[", signature(x = "testClass", i = "ANY", j="ANY"),
  function (x, i, j, ..., drop){
    print("void function")
  }
)