R: Add Tests to Examples

# Add Tests to Examples

## Documentation for package ‘testex’ version 0.2.1

- DESCRIPTION file
- User guides, package vignettes and other documentation
- Package NEWS
- Package README

## Help Pages

fallback_expect_no_error | Expect no Error
testex | A syntactic helper for writing quick and easy example tests
testex-roxygen-tags | 'testex' 'roxygen2' tags
testex-testthat | Support for 'testthat' Expectations
test_examples_as_testthat | Execute examples from Rd files as 'testthat' tests
uses_roxygen2 | Checks for use of 'roxygen2'
use_testex | Add 'testex' tags and configure package to fully use 'testex' features
use_testex_as_testthat | Run examples as 'testthat' expectations
with_attached | Temporarily attach a namespace
with_srcref | Raise 'testthat' Expectations With A Known Source Reference