{testthat} `quasi_label` 和 `expect_match` 抛出“错误：参数类型无效”

Question

我是 {testthat} 的新手，我正在为一个修改字符串的函数构建测试，并希望为某些输入模式生成特定的输出。

作为示例（下面的表示形式），add_excitement 在其输入字符串中添加了一个感叹号。当输入“hello”时，它应该返回“hello！”；当给出任何其他输入时，它应该不返回“hello！”。我想{testthat}一系列模式的行为并返回信息性错误，指定哪个模式导致错误。

根据 {testthat} 包文档，我相信我应该使用expect_match。但是，这会引发“无效参数类型”错误，而 expect_identical 有效。我不明白为什么会这样。我的问题是：

• 为什么expect_identical 而不是expect_match 接受quasi_label 参数？
• 我是否可以使用 expect_identical 而不是 expect_match 来实现我的目的，或者这会带来其他错误的风险吗？

这是一个代表：

library(testthat)
library(purrr)

patterns = c("hello", "goodbye", "cheers")
add_excitement <- function(pattern) paste0(pattern, "!")

# For a single pattern
show_failure(expect_identical(add_excitement(!!patterns[2]), "hello!"))
#> Failed expectation:
#> add_excitement("goodbye") not identical to "hello!".
#> 1/1 mismatches
#> x[1]: "goodbye!"
#> y[1]: "hello!"
try(
  show_failure(expect_match(add_excitement(!!patterns[2]), "hello!", fixed = TRUE,all = TRUE))
)
#> Error in !patterns[2] : invalid argument type

# For multiple patterns
purrr::map(
  patterns, 
  ~ show_failure(expect_identical(add_excitement(!!.), "hello!"))
)
#> Failed expectation:
#> add_excitement("goodbye") not identical to "hello!".
#> 1/1 mismatches
#> x[1]: "goodbye!"
#> y[1]: "hello!"
#> Failed expectation:
#> add_excitement("cheers") not identical to "hello!".
#> 1/1 mismatches
#> x[1]: "cheers!"
#> y[1]: "hello!"
#> [[1]]
#> NULL
#> 
#> [[2]]
#> NULL
#> 
#> [[3]]
#> NULL

try(
  purrr::map(
    patterns, 
    ~ show_failure(expect_match(add_excitement(!!.), "hello!", 
                                fixed = TRUE, all = TRUE)
    )
  )
)
#> Error in !. : invalid argument type

^{由reprex package (v0.3.0) 于 2021-02-04 创建}

感谢您的帮助！

Answer 1

我能够在 https://r-pkgs.org/tests.html#building-your-own-testing-tools 之后解决这个问题，它使用非标准评估 bquote() 和 eval()（而不是 quasi_label()）来产生更多信息错误。

library(testthat)
library(purrr)

patterns = c("hello", "goodbye", "cheers")
add_excitement <- function(pattern) paste0(pattern, "!")

show_failure(eval(bquote(expect_match(add_excitement(.(patterns[2])), "hello!", fixed = TRUE, all = TRUE))))
#> Failed expectation:
#> add_excitement("goodbye") does not match "hello!".
#> Actual value: "goodbye!"


purrr::walk(
  patterns,
  ~ show_failure(eval(bquote(expect_match(add_excitement(.(.)), "hello!", fixed = TRUE, all = TRUE))))
)
#> Failed expectation:
#> add_excitement("goodbye") does not match "hello!".
#> Actual value: "goodbye!"
#> Failed expectation:
#> add_excitement("cheers") does not match "hello!".
#> Actual value: "cheers!"

^{由reprex package (v0.3.0) 于 2021 年 2 月 4 日创建}

或者对于一个整洁的版本：

library(testthat)
library(purrr)

patterns = c("hello", "goodbye", "cheers")
add_excitement <- function(pattern) paste0(pattern, "!")

expect_hello <- function(pattern) {
  show_failure(eval(bquote(expect_match(add_excitement(.(pattern)), "hello!", fixed = TRUE, all = TRUE))))
}

expect_hello(patterns[2])
#> Failed expectation:
#> add_excitement("goodbye") does not match "hello!".
#> Actual value: "goodbye!"

walk(patterns, expect_hello)
#> Failed expectation:
#> add_excitement("goodbye") does not match "hello!".
#> Actual value: "goodbye!"
#> Failed expectation:
#> add_excitement("cheers") does not match "hello!".
#> Actual value: "cheers!"

^{由reprex package (v0.3.0) 于 2021-02-04 创建}

Answer 2

该错误与tidyeval bang bang !! operator 的使用有关。
This is superseded，您提供的示例没有：

show_failure(expect_identical(add_excitement(patterns[2]), "hello!"))

# Failed expectation:
# add_excitement(patterns[2]) not identical to "hello!".
# 1/1 mismatches
# x[1]: "goodbye!"
# y[1]: "hello!"

show_failure(expect_match(add_excitement(patterns[2]), "hello!", fixed = TRUE,all = TRUE))

# Failed expectation:
# add_excitement(patterns[2]) does not match "hello!".
# Actual value: "goodbye!"

purrr::map(
  patterns, 
  ~ show_failure(expect_match(add_excitement(.x), "hello!", 
                              fixed = TRUE, all = TRUE)
  )
)

Failed expectation:
add_excitement(.x) does not match "hello!".
Actual value: "goodbye!"
Failed expectation:
add_excitement(.x) does not match "hello!".
Actual value: "cheers!"
[[1]]
NULL

[[2]]
NULL

[[3]]
NULL