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runit-testingtestthat

Expect_equal() with empty string

I want to test a function with expect_equal() from the testthat package in R that extracts information from a string separated by |. I also want to test the case when the input string is empty. However, in this case I do not achieve the expected equality (see code snippet below). I get the error "Error: result not equal to expected. Component “info2”: 'is.NA' value mismatch: 0 in current 1 in target". How to solve this?

library(stringr)
library(testthat)


# Function to be tested
fn_extract_info <- function(some_text) {
  
  info1 <- unlist(
    stringr::str_split(
      some_text, "\\|"))[1]
  
  info2 <- unlist(
    stringr::str_split(
      some_text, "\\|"))[2]
  
  return(list(
    info1 = info1,
    info2 = info2
  ))
  
}

# Test function
fn_test_fn_extract_info <- function(some_text, expected) {
  
  result <- fn_extract_info(some_text = some_text)
  
  expect_equal(result, expected)
  
}

# Execution of test function with empty string
fn_test_fn_extract_info(
  some_text = "", 
  expected = list(info1 = "",
                  info2 = "NA")
  )

The function fn_extract_info() with an empty string as input produces:

$info1
[1] ""

$info2
[1] NA
Solution

  • Note that "NA" is not the same as NA. And also not all NA values are created the same. If you are expecting a missing character value, you should run this instead

    fn_test_fn_extract_info(
  some_text = "", 
  expected = list(info1 = "",
                  info2 = NA_character_)
)

    NA_character_ is the special typed version of NA for character values.