Checking package installation

package_install.R

if(!require(testthat)) {
	install.package("testthat")
}

library(testthat)
# If you're going to require dplyr it would make sense to have students be on at least version 3.
expect_equal(R.version$major, "3")
package_list <- installed.packages (fields = c ("Package", "Version"))
# Next check to see that people have at least the major versions of key packages
expect_equal(package_list["plyr","Version"], "1.8")
# And similarly for the remaining packages

# Last bit only makes sense if you need the use of devtools
# Looks like you don't though since you wont be installing anything from GitHub
# or teaching any parts of package developement. In case you needed it:

library(devtools)
expect_true(has_devel())

# This should return true of people have correctly followed instructions for their OS.
# More info here:  https://github.com/karthik/dlab-advanced-r/blob/master/installation.md#installation