Escape md link targets for '%'

Closes #1209.

NEWS.md

@@ -1,5 +1,8 @@
 # roxygen2 (development version)
 
+* Percent signs in markdown link targets, e.g. `[text](https://foo/ba%20r)`
+  are now handled correctly (#1209).
+
 * The new `@exmaplesIf` tag can be used to create conditional
   examples. These examples only run if a specified condition
   holds (#962).

R/markdown.R

@@ -333,7 +333,10 @@ mdxml_link <- function(xml, state) {
   } else if (dest == "" || dest == xml_text(xml)) {
     paste0("\\url{", escape_comment(xml_text(xml)), "}")
   } else {
-    paste0("\\href{", dest, "}{", mdxml_link_text(contents, state), "}")
+    paste0(
+      "\\href{", escape_comment(dest), "}",
+      "{", mdxml_link_text(contents, state), "}"
+    )
   }
 }
 

tests/testthat/test-markdown-link.R

@@ -446,3 +446,19 @@ test_that("linking to self is unqualified", {
     "foo \\code{\\link[=fun]{fun()}} and \\link{obj} bar"
   )
 })
+
+test_that("percents are escaped in link targets", {
+  out1 <- roc_proc_text(rd_roclet(), "
+    #' Title
+    #'
+    #' [link % text](https://foo.bar/link%20target)
+    #' @md
+    foo <- function() {}")[[1]]
+  out2 <- roc_proc_text(rd_roclet(), "
+    #' Title
+    #'
+    #' \\href{https://foo.bar/link%20target}{link % text}
+    #' @md
+    foo <- function() {}")[[1]]
+  expect_equivalent_rd(out1, out2)
+})