test_that expect_silent fails with sink

[lcougnaud]

I use sink to export the messages (message/warning/error) generated by R function to a log file in a R package (via a specific parameter logFile).
I would expect expect_silent to return TRUE if the output is exported to a file with sink, as no message/warning/error are printed to the console.
However, expect_silent mentions that messages have been produced:

library(testthat)
myFct <- function(logFile = NULL){
  if(!is.null(logFile)){
      logFileCon <- file(logFile, "w");
      sink(file = logFileCon, type = "message");
      on.exit(sink(type="message"))
  }
  message("This is a test message")
}
testthat::expect_silent(myFct(logFile = "log.txt")))
Error: `myFct(logFile = "log.txt")` produced messages.

(This could be linked to #460)

[hadley]

Unfortunately I think it's going to be too difficult to tell if sink() is activated inside of expect_silent(), so you'll need to tackle this a different way.

[pdbailey0]

I can reproduce this by sleeping my computer. The problem appears to be with the temporary file not being a valid path and not being opened in such a way that the containing folder is created. a tryCatch seems like it could fix this by simply creating the path. But the actual problem is that this file is not valid and that's not part of testthat.