Pull out scope helper

And use in oauth_service_token(). Fixes r-lib#389

NEWS.md

@@ -1,5 +1,8 @@
 # httr 1.2.1.9000
 
+* `oauth_service_token()` now accepts a character vector containing multiple
+  scopes as described in the documentation (#389).
+
 * Don't export `length()` method for internal `path` class (#395)
 
 * New oauth cache files are always added to `.gitignore` and, if it exists, `.Rbuildignore`. Specifically, this now happens when option `httr_oauth_cache = TRUE` or user specifies cache file name explicitly. (@jennybc #436)

R/oauth-init.R

@@ -82,7 +82,7 @@ init_oauth2.0 <- function(endpoint, app, scope = NULL, user_params = NULL,
     state <- nonce()
   }
 
-  scope_arg <- paste(scope, collapse = ' ')
+  scope_arg <- check_scope(scope)
 
   authorize_url <- modify_url(endpoint$authorize, query = compact(list(
     client_id = app$key,
@@ -121,3 +121,14 @@ init_oauth2.0 <- function(endpoint, app, scope = NULL, user_params = NULL,
   stop_for_status(req, task = "get an access token")
   content(req, type = type)
 }
+
+check_scope <- function(x) {
+  if (is.null(x)) {
+    return(NULL)
+  }
+
+  if (!is.character(x)) {
+    stop("`scope` must be a character vector", call. = FALSE)
+  }
+  paste(x, collapse = ' ')
+}

R/oauth-token.r

@@ -273,8 +273,8 @@ oauth_service_token <- function(endpoint, secrets, scope = NULL) {
     stop("`endpoint` must be an OAuth endpoint", call. = FALSE)
   if (!is.list(secrets))
     stop("`secrets` must be a list.", call. = FALSE)
-  if (!is.null(scope) && !(is.character(scope) && length(scope) == 1))
-    stop("`scope` must be a length 1 character vector.", call. = FALSE)
+
+  scope <- check_scope(scope)
 
   TokenServiceAccount$new(
     endpoint = endpoint,

tests/testthat/test-oauth.R

@@ -52,3 +52,16 @@ test_that("oauth_encode1 works", {
 
   expect_equal(orig_string, restored_string)
 })
+
+
+# Parameter checking ------------------------------------------------------
+
+test_that("scope must be character or NULL", {
+  expect_equal(check_scope("a"), "a")
+  expect_equal(check_scope(NULL), NULL)
+  expect_error(check_scope(1), "character vector")
+})
+
+test_that("multiple scopes collapsed with space", {
+  expect_equal(check_scope(c("a", "b")), "a b")
+})