Fix override when used in as_pkgdown() (#2406)

Fixes #2257

R/package.R

@@ -9,6 +9,7 @@
 #' @export
 as_pkgdown <- function(pkg = ".", override = list()) {
   if (is_pkgdown(pkg)) {
+    pkg$meta <- modify_list(pkg$meta, override)
     return(pkg)
   }
 
@@ -21,7 +22,7 @@ as_pkgdown <- function(pkg = ".", override = list()) {
 
   desc <- read_desc(pkg)
   meta <- read_meta(pkg)
-  meta <- utils::modifyList(meta, override)
+  meta <- modify_list(meta, override)
 
   template_config <- find_template_config(
     package = meta$template$package,

R/utils.R

@@ -86,7 +86,9 @@ isFALSE <- function(x) {
 }
 
 modify_list <- function(x, y) {
-  if (is.null(y)) {
+  if (is.null(x)) {
+    return(y)
+  } else if (is.null(y)) {
     return(x)
   }
 

tests/testthat/test-package.R

@@ -48,6 +48,15 @@ test_that("package_vignettes() sorts articles alphabetically by file name", {
   )
 })
 
+test_that("override works correctly for as_pkgdown", {
+  pkgdown <- as_pkgdown("assets/man-figures")
+  expected_list <- list(figures = list(dev = "jpeg", fig.ext = "jpg", fig.width = 3, fig.asp = 1))
+  expect_equal(pkgdown$meta, expected_list)
+  modified_pkgdown <- as_pkgdown(pkgdown, override = list(figures = list(dev = "png")))
+  modified_list <- list(figures = list(dev = "png", fig.ext = "jpg", fig.width = 3, fig.asp = 1))
+  modified_pkgdown$meta
+  expect_equal(modified_pkgdown$meta, modified_list)
+})
 # titles ------------------------------------------------------------------
 
 test_that("multiline titles are collapsed", {