Don't prompt user to install template package from CRAN

Fixes #2076

NEWS.md

@@ -1,5 +1,6 @@
 # pkgdown (development version)
 
+* `as.pkgdown()` will no longer prompt you to install a missing template package from CRAN, since these are almost always found in GitHub (#2076).
 * `init_site()` once again describes one copy per line, and now uses a better prefix when copying assets from pkgdown itself (#2445).
 * Very wide words are now automatically broken across lines and hyphenated (when possible) when they'd otherwise create a horizontal scrollbar on mobile (#1888).
 * The `repo.source.url` field no longer requires a trailing slash (#2017).

R/package.R

@@ -331,12 +331,19 @@ package_vignettes <- function(path = ".") {
   out[order(basename(out$file_out)), ]
 }
 
-find_template_config <- function(package, bs_version = NULL) {
+find_template_config <- function(package,
+                                 bs_version = NULL,
+                                 error_call = caller_env()) {
   if (is.null(package)) {
     return(list())
   }
 
-  config <- path_package_pkgdown("_pkgdown.yml", package, bs_version)
+  config <- path_package_pkgdown(
+    "_pkgdown.yml",
+    package,
+    bs_version,
+    error_call = error_call
+  )
   if (!file_exists(config)) {
     return(list())
   }

R/utils-fs.R

@@ -96,8 +96,21 @@ path_first_existing <- function(...) {
   NULL
 }
 
-path_package_pkgdown <- function(path, package, bs_version) {
-  check_installed(package)
+path_package_pkgdown <- function(path,
+                                 package,
+                                 bs_version,
+                                 error_call = caller_env()) {
+  # package will usually be a github package, and check_installed()
+  # tries to install from CRAN, which is highly likely to fail.
+  if (!is_installed(package)) {
+    cli::cli_abort(
+      c(
+        "Template package {.val {package}} is not installed.",
+        i = "Please install before continuing"
+      ),
+      call = error_call
+    )
+  }
   base <- system_file("pkgdown", package = package)
 
   # If bs_version supplied, first try for versioned template

tests/testthat/_snaps/utils-fs.md

@@ -0,0 +1,9 @@
+# missing template package yields custom error
+
+    Code
+      path_package_pkgdown("x", "missing", 3)
+    Condition
+      Error:
+      ! Template package "missing" is not installed.
+      i Please install before continuing
+

tests/testthat/test-utils-fs.R

@@ -0,0 +1,3 @@
+test_that("missing template package yields custom error", {
+  expect_snapshot(path_package_pkgdown("x", "missing", 3), error = TRUE)
+})