fuzzr

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fuzzr implements some simple "fuzz tests" for your R functions, passing in a wide array of inputs and returning a report on how your function reacts.

Installation

install.package("fuzzr")

# Or, for the development version:
devtools::install_github("mdlincoln/fuzzr")

Usage

Tests are set by passing functions that return named lists of input values. These values will be passed as function arguments. Several default suites are provided with this package, such as test_char, however you may implement your own by passing a function that returns a similarly-formatted list.

library(fuzzr)
str(test_char())
#> List of 8
#>  $ char_empty         : chr(0) 
#>  $ char_single        : chr "a"
#>  $ char_single_blank  : chr ""
#>  $ char_multiple      : chr [1:3] "a" "b" "c"
#>  $ char_multiple_blank: chr [1:4] "a" "b" "c" ""
#>  $ char_with_na       : chr [1:3] "a" "b" NA
#>  $ char_single_na     : chr NA
#>  $ char_all_na        : chr [1:3] NA NA NA

Evaluate a function argument by supplying fuzz_function its quoted name, the tests to run, along with any other required static values. fuzz_function returns a fuzz_results object that stores conditions raised by a function (message, warning, or error) along with any value returned by that function.

fuzz_results <- fuzz_function(fun = lm, arg_name = "subset", data = iris, 
                              formula = Sepal.Length ~ Petal.Width + Petal.Length, 
                              tests = test_all())

You can render these results as a data frame:

fuzz_df <- as.data.frame(fuzz_results)
knitr::kable(head(fuzz_df))
subset data formula output messages warnings errors result_classes results_index
char_empty iris Sepal.Length ~ Petal.Width + Petal.Length NA NA NA 0 (non-NA) cases NA 1
char_single iris Sepal.Length ~ Petal.Width + Petal.Length NA NA NA 0 (non-NA) cases NA 2
char_single_blank iris Sepal.Length ~ Petal.Width + Petal.Length NA NA NA 0 (non-NA) cases NA 3
char_multiple iris Sepal.Length ~ Petal.Width + Petal.Length NA NA NA 0 (non-NA) cases NA 4
char_multiple_blank iris Sepal.Length ~ Petal.Width + Petal.Length NA NA NA 0 (non-NA) cases NA 5
char_with_na iris Sepal.Length ~ Petal.Width + Petal.Length NA NA NA 0 (non-NA) cases NA 6

You can also access the value returned by any one test by matching the argument tested with its test name:

model <- fuzz_value(fuzz_results, subset = "int_multiple")
coefficients(model)
#>  (Intercept)  Petal.Width Petal.Length 
#>          0.8           NA          3.0

Multiple-argument tests

Specify multiple-argument tests with p_fuzz_function, passing a named list of arguments and tests to run on each. p_fuzz_function will test every combination of argument and variable.

fuzz_p <- p_fuzz_function(agrep, list(pattern = test_char(), x = test_char()))
length(fuzz_p)
#> [1] 64
knitr::kable(head(as.data.frame(fuzz_p)))
pattern x output messages warnings errors result_classes results_index
char_empty char_empty NA NA NA invalid 'pattern' argument NA 1
char_single char_empty NA NA NA NA integer 2
char_single_blank char_empty NA NA NA 'pattern' must be a non-empty character string NA 3
char_multiple char_empty NA NA argument 'pattern' has length > 1 and only the first element will be used NA integer 4
char_multiple_blank char_empty NA NA argument 'pattern' has length > 1 and only the first element will be used NA integer 5
char_with_na char_empty NA NA argument 'pattern' has length > 1 and only the first element will be used NA integer 6

Matthew Lincoln