R tryCatch与testthat期望

Question

我有以下功能:

fun = function(expr) {
  mc = match.call()

  env = as.environment(within(
    list(),
    expr = eval(mc$expr)
  ))

  return(env)
}

在一个内部调用,tryCatch()以便expr优雅地处理任何错误条件.

它在标准错误条件下工作正常:

tryCatch({
  fun({
    stop('error')
  })
}, error = function(e) {
  message('error happened')
})

# error happened

但是,它不会捕获testthat期望错误(这是我特定用例的首选):

library(testthat)

tryCatch({
  fun({
    expect_true(FALSE)
  })
}, error = function(e) {
  message('expectation not met')
})

# Error: FALSE isn't true.

或更简单地说:

library(testthat)

tryCatch({
  expect_true(FALSE)
}, error = function(e) {
  message('expectation not met')
})

# Error: FALSE isn't true.

期望错误未被捕获.

从R 3.2.2升级到R 3.3.0之后出现了这个问题 - 即期望错误在R 3.2.2中被捕获.

有没有办法让R 3.3.0中的testthat期望得到满足tryCatch()？

Answer 1

我设置调试器expect()然后逐步执行几行代码(为简洁起见编辑输出),并查看发出信号的条件的类

> debug(expect)
> xx = expect_true(FALSE)
...
Browse[2]> n
debug: exp <- as.expectation(exp, ..., srcref = srcref)
Browse[2]>
...
Browse[2]> class(exp)
[1] "expectation_failure" "expectation"         "condition"   
Browse[2]> Q
> undebug(expect)       

所以它不是类'错误'的条件,可以明确地捕获

> tryCatch(expect_true(FALSE), expectation_failure=conditionMessage)
[1] "FALSE isn't true.\n"

你也可以expectation上课.

重启允许你继续,如果这是重要的.

result <- withCallingHandlers({
    expect_true(FALSE)
    expect_true(!TRUE)
    expect_true("this sentence")
}, expectation_failure=function(e) {
    cat(conditionMessage(e))
    invokeRestart("continue_test")
})

与输出

FALSE isn't true.
!TRUE isn't true.
"this sentence" isn't true.
> result
[1] FALSE

人们也可以抓住或处理成功

> tryCatch(expect_true(TRUE), expectation_success=class)
[1] "expectation_success" "expectation"         "condition"