This is a follow up from a previous question.
How to integrate new R6Class functions stored in independent files into an existing R package?
In summary, in trying to load a function stored in a file. I managed to do it by altering manually the NAMESPACE and Collate in the DESCRIPTION and rebuilding the package. However, I am sure this is not standard practice since the package already has a man folder and .Rd files created with roxygen2. However, when I try to use roxygen2 to manage my NAMESPACE and Collate in the DESCRIPTION, the following error pops up.
==> devtools::document(roclets=c('rd', 'collate', 'namespace'))
Updating mypackage documentation
Loading mypackage
Error in loadNamespace(name) : there is no package called ‘testthat’
Calls: suppressPackageStartupMessages ... tryCatch -> tryCatchList -> tryCatchOne -> <Anonymous>
Execution halted
Exited with status 1.
The working directory contains a folder tests with a testhat.R file and a second folder full of functions.
Any hint of why roxygen2 is falling to produce the documentation and update the NAMESPACE and DESCRIPTION?
You need to install the testthat package
testthat is a package that is
A unit testing system designed to be fun, flexible and easy to set up.
The test section of Hadley's R Packages book (online) is a good guide on how to use it.
In fact, I recommend going through the whole book as it will introduce you to some best-practices for creating packages. I've used it a lot!