如何测试自定义期望？

Question

假设我想要一个自定义的testthat期望。例如，我正在测试许多对象，看看它们是否没有缺失值。写东西的testhat方法应该是这样的：

expect_no_nas <- function(object, info = NULL, label = NULL)
{
  lab <- testthat:::make_label(object, label)
  expect(has_no_nas(object), sprintf("%s has nulls.", lab), 
    info = info)
  invisible(object)
}

has_no_nas <- function()
{
  !any(is.na(x))
}

我如何测试它是正确的？

我可以写通过的测试，没问题。

test_that(
  "expect_no_nas passes when there are no NAs",
  {
    expect_no_nas(1:5)
  }
)

我认为我可以将自定义期望包装在expect_error中，但这不起作用：

test_that(
  "expect_no_nas fails when there are NAs",
  {
    expect_error(expect_no_nas(c(1, NA)))
  }
)   
## Error: Test failed: 'expect_no_nas fails when there are NAs'
## * Not expected: c(1, NA) has NAs.
## * Not expected: expect_no_nas(c(1, NA)) code raised an error.

将其包装在try中也不起作用。

test_that(
  "expect_no_nas fails when there are NAs",
  {
    res <- try(expect_no_nas(c(1, NA)))
    expect_false(res$passed)
  }
) 
## Error: Test failed: 'expect_no_nas fails when there are NAs'
## Not expected: c(1, NA) has NAs.    

我如何测试失败的案例？(重要的是要记住，我们是在测试expect_no_nas是否工作，而不仅仅是编写使用expect_no_nas的测试。)

Answer 1

Nico的查询有助于澄清这一点:您需要在测试中进行测试。

test_that(
  "expect_no_nas fails when there are NAs",
  {
    expect_error(
      test_that(
        "failing test",
        {
          expect_no_nas(c(1, NA))
        }
      ) 
    )
  }
)