如何在预期时使用 testthat 将消息和警告静音

Question

为了开发一个包，我使用testthat。我想测试我的函数是否发送正确的消息和警告。我想同时测试函数的结果。这就是我正在尝试的方式：

## R/foo.r
foo <- function() {
  message("This is a message")
  warning("This is a warning")
  "This is a result"
}

我编写了这些测试：

## tests/testthat/test-foo.R

test_that("foo works", {
  expect_equal(foo(), "This is a result")
  expect_message(foo(), "This is a message")
  expect_warning(foo(), "This is a warning")
})

但是现在当我运行测试时，我有这个：

Loading testWarnMess
Testing testWarnMess
v |  OK F W S | Context
/ |   0       | foo                                                                           This is a message
v |   3   2   | foo [0.3 s]                                                                   
----------------------------------------------------------------------------------------------
Warning (test-foo.R:2:3): foo works
This is a warning
Backtrace:
 1. testthat::expect_equal(foo(), "This is a result") test-foo.R:2:2
 4. testWarnMess::foo()

Warning (test-foo.R:3:3): foo works
This is a warning
Backtrace:
 1. testthat::expect_message(foo(), "This is a message") test-foo.R:3:2
 7. testWarnMess::foo()
----------------------------------------------------------------------------------------------

== Results ===================================================================================
Duration: 0.3 s

[ FAIL 0 | WARN 2 | SKIP 0 | PASS 3 ]
This is a message

当我预期它们会发生时，如何防止在测试结果中看到消息和警告？

Answer 1

一个很好的方法是使用副词purrr::quietly。

test_that("foo works", {
  qfoo <- purrr::quietly(foo)
  qfoo_call <- qfoo()
  expect_equal(qfoo_call$result, "This is a result")
  expect_equal(qfoo_call$message, "This is a message")
  expect_equal(qfoo_call$warning, "This is a warning")
})