Checks if a Number is Valid Using the Luhn Algorithm
Confirms if the number is Luhn compliant.
Can check if credit card, IMEI number or any other Luhn based number is correct.
For more info see: <https://en.wikipedia.org/wiki/Luhn_algorithm>.

c(
person("Adam", "Deacon", email = "adam@deaconsworld.org.uk", role = c("aut", "cre")),
person("Karina", "Marks", email = "kmarks@mango-solutions.com", role = c("ctb")),
person("Owen", "Jones", email = "olj23@bath.ac.uk", role = c("ctb"))
)
Adam Deacon [aut, cre],
Karina Marks [ctb],
Owen Jones [ctb]

Check the Basic Validity of a (Function) Argument
c(person("Ivo Van Walle", "Developer", role = c("aut", "cre"),
email = "ivo.van.walle@gmail.com"))
Utility functions that allow checking the basic validity of a function argument or any other value,
including generating an error and assigning a default in a single line of code. The main purpose of
the package is to provide simple and easily readable argument checking to improve code robustness.
Ivo Van Walle Developer <ivo.van.walle@gmail.com>

Check-Fields and Check-Boxes for 'rmarkdown'
Creates auto checking check-fields and check-boxes for 'rmarkdown' html. It could be used in class, when teacher share materials and tasks, so student can solve some problems and check themselves. In contrast with the 'learnr' package the 'checkdown' package works without 'shiny'.

c(person("George", "Moroz",
role = c("aut", "cre"),
email = "agricolamz@gmail.com",
comment = c(ORCID="0000-0003-1990-6083")))

Michel Lang <michellang@gmail.com>,
Bernd Bischl <bernd_bischl@gmx.net>

Tests and assertions to perform frequent argument checks. A
substantial part of the package was written in C to minimize any worries
about execution time overhead.

ggplot2, microbenchmark, knitr, data.table, dplyr

data.table, dplyr, ggplot2, knitr, microbenchmark, testthat

data.table, devtools, dplyr, ggplot2, knitr, rmarkdown,
magrittr, microbenchmark, testthat
'AssertCollection.r' 'allMissing.r' 'anyInfinite.r'
'anyMissing.r' 'anyNaN.r' 'asInteger.r' 'assert.r'
'backports.r' 'helper.r' 'makeExpectation.r' 'makeTest.r'
'makeAssertion.r' 'checkAccess.r' 'checkArray.r'
'checkAtomic.r' 'checkAtomicVector.r' 'checkCharacter.r'
'checkChoice.r' 'checkClass.r' 'checkComplex.r' 'checkCount.r'
'checkDataFrame.r' 'checkDataTable.r' 'checkDirectory.r'
'checkEnvironment.r' 'checkFactor.r' 'checkFile.r'
'checkFlag.r' 'checkFunction.r' 'checkInt.r' 'checkInteger.r'
'checkIntegerish.r' 'checkList.r' 'checkLogical.r'
'checkMatrix.r' 'checkNamed.r' 'checkNames.r' 'checkNull.r'
'checkNumber.r' 'checkNumeric.r' 'checkPathForOutput.r'
'checkScalar.r' 'checkScalarNA.r' 'checkSetEqual.r'
'checkString.r' 'checkSubset.r' 'checkVector.r' 'coalesce.r'
'isIntegerish.r' 'qassert.r' 'qassertr.r' 'wfwl.r' 'zzz.r'