Store current platform line ending in use_rstudio() (r-lib#1072)

* Set default line ending in `use_rstudio()`. Fixes r-lib#1002
* Respect current project line ending in `write_utf8()`. Fixes r-lib#767.

Author: hadley

Diff for: NEWS.md

@@ -1,5 +1,14 @@
 # usethis (development version)
 
+* `use_rstudio()` now sets the `LineEndingConversion` to your `Posix` so that
+  packages created using usethis always use LF line endings, regardless of 
+  who contributes to them (#1002).
+  
+* When writing files, usethis now respects line endings. Default line endings 
+  are taken from the `.Rproj` file (if available), otherwise the `DESCRIPTION`,
+  otherwise the first file found in `R/`, then all else failing to your 
+  platform default (#767).
+
 * `use_testthat()` and `use_test()` now works in projects, not just packages 
   (#1017).
 

Diff for: R/line-ending.R

@@ -0,0 +1,41 @@
+proj_line_ending <- function() {
+  # First look in .Rproj file
+  proj_path <- proj_path(paste0(project_name(), ".Rproj"))
+  if (file_exists(proj_path)) {
+    config <- read_utf8(proj_path)
+
+    if (any(grepl("^LineEndingConversion: Posix", config))) {
+      return("\n")
+    } else if (any(grepl("^LineEndingConversion: Windows", config))) {
+      return("\r\n")
+    }
+  }
+
+  # Then try DESCRIPTION
+  desc_path <- proj_path("DESCRIPTION")
+  if (file_exists(desc_path)) {
+    return(detect_line_ending(desc_path))
+  }
+
+  # Then try any .R file
+  r_path <- proj_path("R")
+  if (dir_exists(r_path)) {
+    r_files <- dir_ls(r_path, pattern = "\\.[rR]$")
+    if (length(r_files) > 0) {
+      return(detect_line_ending(r_files[[1]]))
+    }
+  }
+
+  # Then give up - this is used (for example), when writing the
+  # first file into the package
+  platform_line_ending()
+}
+
+platform_line_ending <- function() {
+  if (.Platform$OS.type == "windows") "\r\n" else "\n"
+}
+
+detect_line_ending <- function(path) {
+  samp <- suppressWarnings(readChar(path, nchars = 500))
+  if (isTRUE(grepl("\r\n", samp))) "\r\n" else "\n"
+}

Diff for: R/rstudio.R

@@ -10,10 +10,16 @@
 #'   * Adds RStudio files to `.gitignore`
 #'   * Adds RStudio files to `.Rbuildignore`, if project is a package
 #'
+#' @param line_ending Line ending
 #' @export
-use_rstudio <- function() {
+use_rstudio <- function(line_ending = c("posix", "windows")) {
+  line_ending <- arg_match(line_ending)
+  line_ending <- c("posix" = "Posix", "windows" = "Windows")[[line_ending]]
+
   rproj_file <- paste0(project_name(), ".Rproj")
-  new <- use_template("template.Rproj", rproj_file)
+  new <- use_template("template.Rproj", rproj_file,
+    data = list(line_ending = line_ending)
+  )
 
   use_git_ignore(".Rproj.user")
   if (is_package()) {

Diff for: R/utils.R

@@ -58,7 +58,7 @@ is_installed <- function(pkg) {
 pluck_chr <- function(l, what) vapply(l, `[[`, character(1), what)
 
 is_testing <- function() {
-  identical(Sys.getenv("TESTTHAT"), "true")
+  identical(Sys.getenv("TESTTHAT"), "true") || identical(Sys.getenv("R_COVR"), "true")
 }
 
 interactive <- function() {

Diff for: R/write.R

@@ -14,7 +14,7 @@
 #' @keywords internal
 #'
 #' @examples
-#' \dontshow{.old_wd <- setwd(tempdir())}
+#' \dontshow{.old_wd <- setwd(tempdir()); proj_set(force = TRUE)}
 #' write_union("a_file", letters[1:3])
 #' readLines("a_file")
 #' write_union("a_file", letters[1:5])
@@ -92,17 +92,17 @@ read_utf8 <- function(path, n = -1L) {
   base::readLines(path, n = n, encoding = "UTF-8", warn = FALSE)
 }
 
-write_utf8 <- function(path, lines, append = FALSE) {
+write_utf8 <- function(path, lines, append = FALSE, line_ending = proj_line_ending()) {
   stopifnot(is.character(path))
   stopifnot(is.character(lines))
 
-  file_mode <- if (append) "a" else ""
-
+  file_mode <- if (append) "ab" else "wb"
   con <- file(path, open = file_mode, encoding = "utf-8")
   on.exit(close(con), add = TRUE)
 
-  lines <- paste0(lines, "\n", collapse = "")
-  cat(lines, file = con, sep = "")
+  # convert embedded newlines
+  lines <- gsub("\r?\n", line_ending, lines)
+  base::writeLines(enc2utf8(lines), con, sep = line_ending, useBytes = TRUE)
 
   invisible(TRUE)
 }

Diff for: inst/templates/template.Rproj

@@ -9,6 +9,7 @@ Encoding: UTF-8
 
 AutoAppendNewline: Yes
 StripTrailingWhitespace: Yes
+LineEndingConversion: {{line_ending}}
 
 BuildType: Package
 PackageUseDevtools: Yes

Diff for: man/use_rstudio.Rd

@@ -0,0 +1,40 @@
+test_that("can detect path from RStudio project file", {
+  scoped_temporary_package()
+  use_rstudio("posix")
+  expect_equal(proj_line_ending(), "\n")
+
+  file_delete(proj_path(paste(paste0(project_name(), ".Rproj"))))
+  use_rstudio("windows")
+  expect_equal(proj_line_ending(), "\r\n")
+})
+
+test_that("can detect path from DESCRIPTION or .R file", {
+  scoped_temporary_project()
+
+  write_utf8(proj_path("DESCRIPTION"), c("x", "y", "z"), line_ending = "\r\n")
+  expect_equal(proj_line_ending(), "\r\n")
+  file_delete(proj_path("DESCRIPTION"))
+
+  dir_create(proj_path("R"))
+  write_utf8(proj_path("R/test.R"), c("x", "y", "z"), line_ending = "\r\n")
+  expect_equal(proj_line_ending(), "\r\n")
+})
+
+test_that("falls back to platform specific encoding", {
+  scoped_temporary_project()
+  expect_equal(proj_line_ending(), platform_line_ending())
+})
+
+test_that("correctly detect line encoding", {
+  path <- file_temp()
+
+  con <- file(path, open = "wb")
+  writeLines(c("a", "b", "c"), con, sep = "\n")
+  close(con)
+  expect_equal(detect_line_ending(path), "\n")
+
+  con <- file(path, open = "wb")
+  writeLines(c("a", "b", "c"), con, sep = "\r\n")
+  close(con)
+  expect_equal(detect_line_ending(path), "\r\n")
+})

Diff for: man/write-this.Rd

@@ -1,10 +1,11 @@
-context("use_rstudio")
-
 test_that("use_rstudio() creates .Rproj file, named after directory", {
   dir <- scoped_temporary_package(rstudio = FALSE)
   use_rstudio()
   rproj <- path_file(dir_ls(proj_get(), regexp = "[.]Rproj$"))
   expect_identical(path_ext_remove(rproj), path_file(dir))
+
+  # Always uses POSIX line endings
+  expect_equal(proj_line_ending(), "\n")
 })
 
 test_that("a non-RStudio project is not recognized", {

Diff for: tests/testthat/test-line-ending.R

@@ -72,23 +72,24 @@ test_that("write_over() leaves file 'as is'", {
 # https://github.com/r-lib/usethis/issues/514
 test_that("write_ut8 always produces a trailing newline", {
   path <- file_temp()
-  write_utf8(path, "x")
-
-  if (identical(Sys.info()[["sysname"]], "Windows")) {
-    expect_equal(readChar(path, 3), "x\r\n")
-  } else {
-    expect_equal(readChar(path, 2), "x\n")
-  }
+  write_utf8(path, "x", line_ending = "\n")
+  expect_equal(readChar(path, 2), "x\n")
 })
 
 test_that("write_ut8 can append text when requested", {
   path <- file_temp()
-  write_utf8(path, "x")
-  write_utf8(path, "x", append = TRUE)
+  write_utf8(path, "x", line_ending = "\n")
+  write_utf8(path, "x", line_ending = "\n", append = TRUE)
+
+  expect_equal(readChar(path, 4), "x\nx\n")
+})
+
+test_that("write_utf8 respects line ending", {
+  path <- file_temp()
+
+  write_utf8(path, "x", line_ending = "\n")
+  expect_equal(detect_line_ending(path), "\n")
 
-  if (identical(Sys.info()[["sysname"]], "Windows")) {
-    expect_equal(readChar(path, 6), "x\r\nx\r\n")
-  } else {
-    expect_equal(readChar(path, 4), "x\nx\n")
-  }
+  write_utf8(path, "x", line_ending = "\r\n")
+  expect_equal(detect_line_ending(path), "\r\n")
 })

Diff for: tests/testthat/test-use-rstudio.R renamed to tests/testthat/test-rstudio.R

@@ -14,6 +14,7 @@ LaTeX: XeLaTeX
 
 AutoAppendNewline: Yes
 StripTrailingWhitespace: Yes
+LineEndingConversion: Posix
 
 BuildType: Package
 PackageUseDevtools: Yes