The provided functions parse rules which allow to express some of the most frequent argument checks by typing just a few letters.
qassert(x, rules, .var.name = vname(x)) qtest(x, rules) qexpect(x, rules, info = NULL, label = vname(x))
qassert throws an
R exception if object
not comply to at least one of the
rules and returns the tested object invisibly
qtest behaves the same way but returns
FALSE if none of the
qexpect is intended to be inside the unit test framework
The rule is specified in up to three parts.
Class and missingness check. The first letter is an abbreviation for the class. If it is provided uppercase, missing values are prohibited. Supported abbreviations:
|Bool / logical.|
|Integerish (numeric convertible to integer, see |
|Real / double.|
|Numeric (integer or double).|
|String / character.|
|Atomic vector (see |
|List. Missingness is defined as |
|Data.frame. Missingness is checked recursively on columns.|
|placeholder to allow any type.|
NA. Infinite values are not treated as missing, but can be caught using boundary checks (part 3).
Length definition. This can be one of
|length of zero or one,|
|length of at least one, or|
|exact length specified as integer.|
>is also supported.
Range check as two numbers separated by a comma, enclosed by square brackets
(endpoint included) or parentheses (endpoint excluded).
For example, “[0, 3)” results in
all(x >= 0 & x < 3).
The lower and upper bound may be omitted which is the equivalent of a negative or
positive infinite bound, respectively.
[0,) does not.
The same holds for the left (lower) boundary and
E.g., the rule “N1()” checks for a single finite numeric which is not NA,
while “N1[)” allows
The functions are inspired by the blog post of Bogumił Kamiński: http://rsnippets.blogspot.de/2013/06/testing-function-agruments-in-gnu-r.html. The implementation is mostly written in C to minimize the overhead.
# logical of length 1 qtest(NA, "b1")#>  TRUE# logical of length 1, NA not allowed qtest(NA, "B1")#>  FALSE# logical of length 0 or 1, NA not allowed qtest(TRUE, "B?")#>  TRUE# numeric with length > 0 qtest(runif(10), "n+")#>  TRUE# integer with length > 0, NAs not allowed, all integers >= 0 and < Inf qtest(1:3, "I+[0,)")#>  TRUE# either an emtpy list or a character vector with <=5 elements qtest(1, c("l0", "s<=5"))#>  FALSE# data frame with at least one column and no missing value in any column qtest(iris, "D+")#>  TRUE