fix bug with backwards additions

R/add_md.R

@@ -29,8 +29,15 @@ insert_md <- function(body, md, nodes, where = "after", space = TRUE) {
 
 shove_nodes_in <- function(body, new, nodes, where = "after", space = TRUE) {
   if (inherits(nodes, "character")) {
+    xpath <- nodes
     nodes <- xml2::xml_find_all(body, nodes, ns = md_ns())
+  } else {
+    xpath <- NULL
   }
+  if (length(nodes) == 0) {
+    msg <- glue::glue("No nodes matched the expression {sQuote(xpath)}")
+    rlang::abort(msg, class = "insert-md-xpath")
+  } 
   if (!inherits(nodes, c("xml_node", "xml_nodeset"))) {
     rlang::abort("an object of class `xml_node` or `xml_nodeset` was expected",
       class = "insert-md-node"
@@ -83,16 +90,24 @@ add_nodes_to_nodes <- function(new, old, where = "after", space = TRUE) {
     # allow purrr::walk() to work on a single node
     old <- list(old)
   }
-  purrr::walk(old, add_node_siblings, new, where = where, remove = FALSE)
+  purrr::walk(.x = old, .f = add_node_siblings,
+    new = new, where = where, remove = FALSE
+  )
 }
 
 # Add siblings to a node
-add_node_siblings <- function(node, nodes, where = "after", remove = TRUE) {
+add_node_siblings <- function(node, new, where = "after", remove = TRUE) {
   # if there is a single node, then we need only add it
-  if (inherits(nodes, "xml_node")) {
-    xml2::xml_add_sibling(node, nodes, .where = where)
+  if (inherits(new, "xml_node")) {
+    xml2::xml_add_sibling(node, new, .where = where)
   } else {
-    purrr::walk(rev(nodes), ~xml2::xml_add_sibling(node, .x, .where = where))
+    if (where == "after") {
+      # Appending new nodes requires us to insert them from the bottom to
+      # the top. The reason for this is because we are always using the existing
+      # node as a reference.
+      new <- rev(new)
+    }
+    purrr::walk(new, ~xml2::xml_add_sibling(node, .x, .where = where))
   }
   if (remove) xml2::xml_remove(node)
 }

tests/testthat/test-class-yarn.R

@@ -160,7 +160,7 @@ test_that("markdown can be appended to elements", {
   path <- system.file("extdata", "example2.Rmd", package = "tinkr")
   ex <- tinkr::yarn$new(path)
   # append a note after the first heading
-  txt <- c("> Hello from *tinkr*!", ">", ">  :heart: R")
+  txt <- c("The following message is sponsored by me:\n", "> Hello from *tinkr*!", ">", ">  :heart: R")
   # Via XPath ------------------------------------------------------------------
   ex$append_md(txt, ".//md:heading[1]")
   # the block quote has been added to the first heading 
@@ -222,10 +222,12 @@ test_that("markdown can be prepended", {
   nodes <- xml2::xml_find_all(ex$body, 
     ".//node()[contains(text(), 'NERDS')]", ex$ns)
   expect_length(nodes, 0)
-  ex$prepend_md("Table: BIRDS, NERDS", ".//md:table")
+  ex$prepend_md("I come before the table.\n\nTable: BIRDS, NERDS", ".//md:table")
   nodes <- xml2::xml_find_all(ex$body, 
     ".//node()[contains(text(), 'NERDS')]", ex$ns)
   expect_length(nodes, 1)
+  pretxt <- xml2::xml_find_first(nodes[[1]], ".//parent::*/preceding-sibling::*[1]")
+  expect_equal(xml2::xml_text(pretxt), "I come before the table.")
 })
 
 
@@ -235,6 +237,13 @@ test_that("an error happens when you try to append with a number", {
   expect_error(ex$append_md("WRONG", 42), class = "insert-md-node")
 })
 
+test_that("an error happens when you try to append to a non-existant node", {
+  path <- system.file("extdata", "example2.Rmd", package = "tinkr")
+  ex <- tinkr::yarn$new(path)
+  expect_error(ex$append_md("WRONG", ".//md:nope"), 
+    "No nodes matched the expression './/md:nope'",
+    class = "insert-md-xpath")
+})
 
 
 test_that("an error happens when you try to append markdown to disparate elements", {