From 97de9061e45f108051fccd1edfc1f166dec1b3d4 Mon Sep 17 00:00:00 2001
From: Vincent Guyader <10470699+VincentGuyader@users.noreply.github.com>
Date: Sat, 25 Apr 2026 22:41:50 +0200
Subject: [PATCH] Use forward slashes when substituting bib path into Rmd
 template
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create_biblio_file() interpolated tempdir() into the bibliography Rmd
template as-is. On Windows, tempdir() returns a path with backslashes
(e.g. "C:\Users\RUNNER~1\AppData\..."). Once that path landed in the
Rmd, the chunk re-evaluating it tripped over substrings like \U, \R,
\T, which R parses as Unicode escapes — yielding `Error in file():
cannot open the connection` from xfun::pkg_bib at vignette build time.

Convert backslashes to forward slashes before substitution. R accepts
forward-slash paths on Windows, so the resulting string is a valid
file path on every OS. (There was already a commented-out attempt at
this same fix in the source: `# escape \`.)

Add a unit test that asserts the substitution result parses cleanly
and contains no backslash, plus a smoke test that the html artifact is
produced.
---
 R/bibliography.R                   |  5 +++-
 tests/testthat/test-bibliography.R | 40 ++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 tests/testthat/test-bibliography.R

diff --git a/R/bibliography.R b/R/bibliography.R
index 0dead86..001e105 100644
--- a/R/bibliography.R
+++ b/R/bibliography.R
@@ -66,9 +66,12 @@ create_biblio_file <- function(packages, out.dir,
     x = bib_lines[grep("PACKAGES_HERE", bib_lines)])
 
   # path to bib
+  # Use forward slashes: on Windows, tempdir() returns "C:\Users\...",
+  # and a substring like "\U..." is parsed as an invalid Unicode escape
+  # when the chunk is re-evaluated in the Rmd.
   bib_lines[grep("BIBPATH_HERE", bib_lines)] <- gsub(
     pattern = "BIBPATH_HERE",
-    replacement = paste0('"', dir_temp, '"'),
+    replacement = paste0('"', gsub("\\\\", "/", dir_temp), '"'),
     x = bib_lines[grep("BIBPATH_HERE", bib_lines)])
 
   # Link citation
diff --git a/tests/testthat/test-bibliography.R b/tests/testthat/test-bibliography.R
new file mode 100644
index 0000000..ec52408
--- /dev/null
+++ b/tests/testthat/test-bibliography.R
@@ -0,0 +1,40 @@
+test_that("create_biblio_file substitutes BIBPATH with forward slashes", {
+  # On Windows, tempdir() returns a path with backslashes (e.g. "C:\Users\...").
+  # If that path is interpolated as-is into the rendered Rmd, R parses
+  # substrings like "\U..." as Unicode escapes and the chunk fails with
+  # `Error in file(): cannot open the connection`. The substitution must
+  # use forward slashes so the path is a valid R string literal on every OS.
+
+  fake_dir <- "C:\\Users\\RUNNER~1\\AppData\\Local\\Temp\\RtmpXXXX"
+  bib_template <- c(
+    "knitr::write_bib(packages, file.path(BIBPATH_HERE, 'packages.bib'))"
+  )
+  substituted <- gsub(
+    pattern = "BIBPATH_HERE",
+    replacement = paste0('"', gsub("\\\\", "/", fake_dir), '"'),
+    x = bib_template
+  )
+
+  expect_false(grepl("\\\\", substituted))
+  expect_true(grepl("C:/Users/RUNNER~1/AppData/Local/Temp/RtmpXXXX", substituted, fixed = TRUE))
+
+  expect_silent(
+    parse(text = substituted)
+  )
+})
+
+test_that("create_biblio_file produces an html bibliography", {
+  out <- tempfile()
+  dir.create(out)
+
+  suppressMessages(
+    create_biblio_file(
+      packages = c("rmarkdown", "knitr"),
+      out.dir = out,
+      to = "html",
+      edit = FALSE
+    )
+  )
+
+  expect_true(file.exists(file.path(out, "bibliography.html")))
+})