r - 如何正确使用testthat Expect_error()？

Question

expect_error()软件包中testthat的正确用法是什么？我试图从帮助中改编示例，但是当我在错误消息中使用方括号时，此操作将失败。

library(testthat)

# Works
tmp1 <- function() stop("Input is not correct")
    expect_error(tmp1(),"Input is not correct")

# Does not work
tmp2 <- function() stop("Input (x) is not correct")
    expect_error(tmp2(),"Input (x) is not correct")

# Does not work
tmp3 <- function() stop("Input(")
    expect_error(tmp3(),"Input(")

结果是：

> library(testthat)
> 
> # Works
> tmp1 <- function() stop("Input is not correct")
> expect_error(tmp1(),"Input is not correct")
> # Does not work
> tmp2 <- function() stop("Input (x) is not correct")
> expect_error(tmp2(),"Input (x) is not correct")
Error: tmp2() does not match 'Input (x) is not correct'. Actual value: 
Error in tmp2() : Input (x) is not correct
> # Does not work
> tmp3 <- function() stop("Input(")
> expect_error(tmp3(),"Input(")
Error in grepl("Input(", "Error in tmp3() : Input(\n", fixed = FALSE,  : 
  invalid regular expression 'Input(', reason 'Missing ')''

R版本3.0.1（2013-05-16）

Answer 1

第二个参数是一个正则表达式。因此，您应该提供一个有效的正则表达式，例如，这将对3个函数起作用：

## this works for 3 , error message containing Input
lapply(list('tmp1','tmp2','tmp3'),function(x){
   expect_error(do.call(x,list()),"Input.*")
})

## this works for 3 also, but more complicated regular expression
lapply(list('tmp1','tmp2','tmp3'),function(x){
  expect_error(do.call(x,list()),"Input.?\\(?")
})