check_missing_topics() error on CI (#1395)

Fixes #1378

NEWS.md

@@ -1,5 +1,8 @@
 # pkgdown (development version)
 
+* Missing topics makes the build fail when the environment variable `CI` is set
+  to `"true"` (@ThierryO, #1378).
+
 * The default navbar no longer includes a home icon - this took up precious
   horizontal space and wasn't very useful since there is already a link to the 
   home page immediately to its left (#1383).

R/build-reference-index.R

@@ -104,6 +104,14 @@ check_missing_topics <- function(rows, pkg) {
 
   missing <- !in_index & !pkg$topics$internal
   if (any(missing)) {
-    warn(c("Topics missing from index: ", unname(pkg$topics$name[missing])))
+    if (on_ci()) {
+      stop(c("Topics missing from index: ", unname(pkg$topics$name[missing])))
+    } else {
+      warn(c("Topics missing from index: ", unname(pkg$topics$name[missing])))
+    }
   }
 }
+
+on_ci <- function() {
+  isTRUE(as.logical(Sys.getenv("CI")))
+}

R/build-reference.R

@@ -88,6 +88,9 @@
 #'
 #' pkgdown will check that all non-internal topics are included on
 #' the reference index page, and will generate a warning if you have missed any.
+#' When the code is run in a continuous integration environment (i.e. when the
+#' CI envar is "true"), this is an error so that the build will fail if you
+#' forget to include topics in the index.
 #'
 #' ## Icons
 #' You can optionally supply an icon for each help topic. To do so, you'll need

tests/testthat/test-build-reference-index.R

@@ -18,7 +18,10 @@ test_that("warns if missing topics", {
   )
   meta <- list(reference = ref)
   pkg <- as_pkgdown(test_path("assets/reference"), override = meta)
+  withr::local_envvar(new = c(CI = "false"))
   expect_warning(data_reference_index(pkg), "Topics missing")
+  withr::local_envvar(new = c(CI = "true"))
+  expect_error(data_reference_index(pkg), "Topics missing")
 })
 
 test_that("default reference includes all functions", {