package <- "TestPackage"
dir.create(file.path(package, "R"), recursive = TRUE)

cat(file = file.path(package, "DESCRIPTION"), "
Package: TestPackage
Version: 0.0-0
License: GPL (>= 2)
Description: A (one paragraph) description of what
  the package does and why it may be useful.
Title: My First Collection of Functions
Author: First Last [aut, cre]
Maintainer: First Last <First.Last@some.domain.net>
Imports: Matrix, methods
")

cat(file = file.path(package, "NAMESPACE"), "
export(zzz)
importFrom(methods, setClass)
importClassesFrom(Matrix, dgCMatrix, CsparseMatrix)
")

cat(file = file.path(package, "R", paste0(package, ".R")), "
zzz <- function() double(3L)
#setClass(\"whatever\", contains = \"dgCMatrix\")
")

tools:::Rcmd(c("build", package))
tools:::Rcmd(c("INSTALL", Sys.glob(paste0(package, "_*.tar.gz"))))

## unlink(Sys.glob(paste0(package, "*")), recursive = TRUE)