expectation_lint() message and marker bugs

[fangly]

Hi,

I found a few issues with expectation_lint():

> lintr:::expect_lint("x <- 1", NULL)                # markers displayed!
> lintr:::expect_lint("x <- 1\n", NULL)              # markers displayed!
Error:  returned ...
> lintr:::expect_lint("x <- 1\n\n", NULL)            # markers displayed!
Error in stop(exp) : bad error message

> lintr:::expect_lint("x <- 1", "superfluous")
Error:  did not return 1 lints as expected from content:x <- 1
> lintr:::expect_lint("x <- 1\n", "superfluous")
As expected
> lintr:::expect_lint("x <- 1\n\n", "superfluous")
Error in stop(exp) : bad error message

1. Markers displayed:
   When running tests, I expect no lint markers to be displayed in Rstudio (or other IDEs). Simply replacing print(lints) by lints in expectation_lint() fixes this issue.

2. Bad error message:
   This second problem is due to expectation_lint() passing a "msg" containing more than one element to testthat::expect(); the lints variable contains more than one lint. In addition, the name of the linters are supposed to be shown, but since I am using the default linters (using ...), no linter name is shown. Personally, I would drop this information as long as the details of the lints (which contain the linter name) are shown.
   In the case where check=NULL, "msg" could be:

paste0("Got ", length(lints), " lints instead of none!\n", paste0(lints, collapse="\n"))

In the case where check="superfluous", "msg" could be:

paste0("Got ", length(lints), " lints instead of ", length(checks), "!\n", paste0(lints, collapse="\n"))

That's it! Cheers,
Florent

PS/ The sofware versions used are:

• R 3.2.5
• RStudio 1.0.136
• lintr development version (23/02/2017)

[fangly]

Fixed in #214