`test_if` function?

[cboettig]

Would it be appropriate to have a function to support conditional testing, for instance, tests to run only if an API was available, and would otherwise simply inform the user that certain tests couldn't be run but avoid failing the check? It seems this behavior exists in other test suites, e.g. php on skipping-tests.

Or perhaps there's a natural way to do this already? (This issue is potentially related to the httr issue #93)

[hadley]

Could you spell out a bit more how you'd expect the input and output might look?

Maybe related to #136?

[cboettig]

Sure, I was thinking something like the following (though you may imagine a more elegant construction):

test_if("Internet connection is available", { 
    ping_API() # Some function that returns TRUE only if successful, 
                       # otherwise the tests are not run and a warning is produced 
                       # that some tests not run because 'internet connection is available' failed 
     },
     { test_that("A bunch of tests that rely on the API being available", { 
        # Usual test_that construction
      })
  })

[hadley]

I was thinking of an interface more like like:

test_that("A bunch of tests that rely on the API being available", { 
  if (!ping_API()) skip("Internet connection is available") 

  expect_equal(a, b)
  expect_equal(c, d)
})

That would be a bit more verbose because you'd need to repeat the check in each test block, but skip() would be implemented in such a way that you could write:

check_API <- function() {
  if (!ping_API()) skip("Internet connection is available") 
}

test_that("A bunch of tests that rely on the API being available", { 
  check_API()

  expect_equal(a, b)
  expect_equal(c, d)
})

This would have the advantage that you'd see how many tests were skipped. skip() would be implemented something like this:

skip <- function(message = NULL, call = sys.call(-1)) {
  cond <- structure(
    list(message = message, call = call),
    class = c("skip", "condition")
  )

  stop(cond)
}

[cboettig]

looks good to me

On Wed, Apr 9, 2014 at 2:22 PM, Hadley Wickham notifications@github.comwrote:

I was thinking of an interface more like like:

test_that("A bunch of tests that rely on the API being available", { if (!ping_API()) skip("Internet connection is available")
expect_equal(a, b) expect_equal(c, d)})

That would be a bit more verbose because you'd need to repeat the check in
each test block, but skip() would be implemented in such a way that you
could write:

check_API <- function() { if (!ping_API()) skip("Internet connection is available") }
test_that("A bunch of tests that rely on the API being available", { check_API()
expect_equal(a, b) expect_equal(c, d)})

This would have the advantage that you'd see how many tests were skipped.

Reply to this email directly or view it on GitHubhttps://github.com/hadley/testthat/issues/141#issuecomment-40018156
.

Carl Boettiger
UC Santa Cruz
http://carlboettiger.info/

[hadley]

How should the results look in the basic summary reporter? Is this ok?

Basic tests : ..S.....

Should the text of the skipped message be printed? If so, how do you match up the text to the test?

[cboettig]

That summary looks good to me. If printing the text, I would prepend it
with an S or a [Skipped] tag. At the summary level though I'd be fine if
the text message was simply suppressed though.

On Wed, Sep 17, 2014 at 2:27 AM, Hadley Wickham notifications@github.com
wrote:

How should the results look in the basic summary reporter? Is this ok?

Basic tests : ..S.....

Should the text of the skipped message be printed? If so, how do you match
up the text to the test?

—
Reply to this email directly or view it on GitHub
https://github.com/hadley/testthat/issues/141#issuecomment-55869628.

Carl Boettiger
UC Santa Cruz
http://carlboettiger.info/

[hadley]

Ok, I think this is done then :)