I have the following R function within a software package, which outputs Sys.time()
to the output for users to know how the algorithm is proceeding:
func = function(num1, num2){
result = num1 + num2
return(paste0(' ', as.character(Sys.time()), ': with result: ', result))
}
An example of using this function is as follows:
> func(2, 2)
[1] " 2018-03-11 07:24:05: with result: 4"
>
I need to test this function. Normally, I would use the testthat package:
https://cran.r-project.org/web/packages/testthat/index.html
Question: How does one set
the Sys.time() in order to test this function? Are there other methods available to test this?
If there was no Sys.time()
, this process would be simple:
library(testthat)
expect_equal(func(2, 2), 4)
expect_equal(func(2, -2), 0)
expect_error(func('a', 'b'))
You could use something like this.
func <- function(num1, num2){
result = num1 + num2
return(paste0(' ', as.character(Sys.time()), ': with result: ', result))
}
library(testthat)
uses stringr
expect_equal(as.numeric(stringr::str_extract(func(2, 2), "[0-9]*\\.*[0-9]*$")), 4)
expect_equal(as.numeric(stringr::str_extract(func(2, -2), "[0-9]*\\.*[0-9]+$")), 0)
expect_equal(as.numeric(stringr::str_extract(func(15, 21.3), "[0-9]*\\.*[0-9]+$")), 36.3)
uses base r
expect_equal(as.numeric(regmatches(func(2, 2), regexpr("[0-9]*\\.*[0-9]*$", func(2, 2)))), 4)
expect_equal(as.numeric(regmatches(func(2, -2), regexpr("[0-9]*\\.*[0-9]*$", func(2, -2)))), 0)
expect_equal(as.numeric(regmatches(func(15, 21.3), regexpr("[0-9]*\\.*[0-9]*$",func(15, 21.3)))), 36.3)
or test the internals of function exactly, but that depends on what is exactly in your function internals.
expect_equal(func(2, 2), paste0(' ', as.character(Sys.time()), ': with result: ', 4))
expect_equal(func(2, -2), paste0(' ', as.character(Sys.time()), ': with result: ', 0))
expect_equal(func(15, 21.3), paste0(' ', as.character(Sys.time()), ': with result: ', 36.3))