Don't override user-specified NOT_CRAN env var

Continutation of #2112

Author: hadley

R/auto-test.R

@@ -83,7 +83,7 @@ auto_test_package <- function(
   test_path <- normalizePath(file.path(path, "tests", "testthat"))
 
   # Start by loading all code and running all tests
-  withr::local_envvar("NOT_CRAN" = "true")
+  local_assume_not_on_cran()
   pkgload::load_all(path)
   test_dir(
     test_path,

R/local.R

@@ -190,8 +190,7 @@ local_test_directory <- function(path, package = NULL, .env = parent.frame()) {
 }
 
 local_interactive_reporter <- function(.env = parent.frame()) {
-  # Definitely not on CRAN
-  withr::local_envvar(NOT_CRAN = "true", .local_envir = .env)
+  local_assume_not_on_cran()
   withr::local_options(testthat_interactive = TRUE, .local_envir = .env)
 
   # Use edition from working directory

R/skip.R

@@ -190,6 +190,14 @@ local_on_cran <- function(on_cran, frame = caller_env()) {
   withr::local_envvar(NOT_CRAN = tolower(!on_cran), .local_envir = frame)
 }
 
+# Assert that we're not on CRAN, but don't override the user's setting
+local_assume_not_on_cran <- function(frame = caller_env()) {
+  if (Sys.getenv("NOT_CRAN") != "") {
+    return()
+  }
+  withr::local_envvar("NOT_CRAN" = "true", .local_envir = frame)
+}
+
 #' @export
 #' @param os Character vector of one or more operating systems to skip on.
 #'   Supported values are `"windows"`, `"mac"`, `"linux"`, `"solaris"`,

R/test-package.R

@@ -68,7 +68,7 @@ test_local <- function(
   package <- pkgload::pkg_name(path)
   test_path <- file.path(pkgload::pkg_path(path), "tests", "testthat")
 
-  withr::local_envvar(NOT_CRAN = "true")
+  local_assume_not_on_cran()
   test_dir(
     test_path,
     package = package,

tests/testthat/test-skip.R

@@ -88,6 +88,20 @@ test_that("local_on_cran sets NOT_CRAN", {
   })
 })
 
+test_that("local_assume_not_on_cran() sets NOT_CRAN if not already set", {
+  withr::local_envvar(NOT_CRAN = NA)
+  local({
+    local_assume_not_on_cran()
+    expect_equal(Sys.getenv("NOT_CRAN"), "true")
+  })
+
+  withr::local_envvar(NOT_CRAN = "false")
+  local({
+    local_assume_not_on_cran()
+    expect_equal(Sys.getenv("NOT_CRAN"), "false")
+  })
+})
+
 test_that("skip_on_ci() works as expected", {
   withr::local_envvar(CI = "false")
   expect_no_skip(skip_on_ci())