From be8e6b6ae87642c157c5ed6510076ba37e1bc0ed Mon Sep 17 00:00:00 2001
From: Jim Hester <james.f.hester@gmail.com>
Date: Thu, 29 Mar 2018 12:00:46 -0400
Subject: [PATCH] Add skip_if_offline

This is useful for packages which test against online APIs. We use
`curl::nslookup()` rather than `utils::nsl()` because the latter is not
available on Windows.
---
 DESCRIPTION |  1 +
 NAMESPACE   |  1 +
 NEWS.md     |  5 +++++
 R/skip.R    | 14 ++++++++++++++
 man/skip.Rd |  8 ++++++++
 5 files changed, 29 insertions(+)

diff --git a/DESCRIPTION b/DESCRIPTION
index d69c37d05..2acd04001 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -27,6 +27,7 @@ Imports:
     withr (>= 2.0.0)
 Suggests: 
     covr,
+    curl (>= 0.9.5),
     devtools,
     knitr,
     rmarkdown,
diff --git a/NAMESPACE b/NAMESPACE
index d549c6daa..b01386f5a 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -124,6 +124,7 @@ export(skip)
 export(skip_if)
 export(skip_if_not)
 export(skip_if_not_installed)
+export(skip_if_offline)
 export(skip_if_translated)
 export(skip_on_appveyor)
 export(skip_on_bioc)
diff --git a/NEWS.md b/NEWS.md
index 3099fd28d..616909221 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,10 @@
 # testthat 2.0.0.9000
 
+## New and improved skips
+
+* `skip_if_offline()` skips tests if an internet connection is not available
+  (#685).
+
 ## Minor improvements and bug fixes
 
 * `expect_equal_to_reference` `update` parameter default value restored to
diff --git a/R/skip.R b/R/skip.R
index 0392dde4a..d378222ce 100644
--- a/R/skip.R
+++ b/R/skip.R
@@ -14,6 +14,9 @@
 #' `skip_if_not()` works like [stopifnot()], generating
 #' a message automatically based on the first argument.
 #'
+#' `skip_if_offline()` skips tests if an internet connection is not available
+#' using [curl::nslookup()].
+#'
 #' `skip_on_cran()` skips tests on CRAN, using the `NOT_CRAN`
 #' environment variable set by devtools.
 #'
@@ -31,6 +34,7 @@
 #' a side effect, because the package is likely to be used anyway.
 #'
 #' @param message A message describing why the test was skipped.
+#' @param host A string with a hostname to lookup
 #' @export
 #' @examples
 #' if (FALSE) skip("No internet connection")
@@ -98,6 +102,16 @@ skip_if_not_installed <- function(pkg, minimum_version = NULL) {
   return(invisible(TRUE))
 }
 
+#' @export
+#' @rdname skip
+skip_if_offline <- function(host = "r-project.org") {
+  skip_if_not_installed("curl")
+  has_internet <- !is.null(curl::nslookup(host, error = FALSE))
+  if (!has_internet) {
+    skip("offline")
+  }
+}
+
 #' @export
 #' @rdname skip
 skip_on_cran <- function() {
diff --git a/man/skip.Rd b/man/skip.Rd
index b5b86a4b3..7997fca7a 100644
--- a/man/skip.Rd
+++ b/man/skip.Rd
@@ -5,6 +5,7 @@
 \alias{skip_if_not}
 \alias{skip_if}
 \alias{skip_if_not_installed}
+\alias{skip_if_offline}
 \alias{skip_on_cran}
 \alias{skip_on_os}
 \alias{skip_on_travis}
@@ -21,6 +22,8 @@ skip_if(condition, message = deparse(substitute(condition)))
 
 skip_if_not_installed(pkg, minimum_version = NULL)
 
+skip_if_offline(host = "r-project.org")
+
 skip_on_cran()
 
 skip_on_os(os)
@@ -43,6 +46,8 @@ skip_if_translated()
 
 \item{minimum_version}{Minimum required version for the package}
 
+\item{host}{A string with a hostname to lookup}
+
 \item{os}{Character vector of system names. Supported values are
 \code{"windows"}, \code{"mac"}, \code{"linux"} and \code{"solaris"}.}
 }
@@ -63,6 +68,9 @@ statement, not how many expectations were skipped.
 \code{skip_if_not()} works like \code{\link[=stopifnot]{stopifnot()}}, generating
 a message automatically based on the first argument.
 
+\code{skip_if_offline()} skips tests if an internet connection is not available
+using \code{\link[curl:nslookup]{curl::nslookup()}}.
+
 \code{skip_on_cran()} skips tests on CRAN, using the \code{NOT_CRAN}
 environment variable set by devtools.