feat: add exercise featuring a merge conflict

NAMESPACE

@@ -5,6 +5,7 @@ export(exo_bisect)
 export(exo_clean_dir)
 export(exo_committed_to_main)
 export(exo_committed_to_wrong)
+export(exo_conflict)
 export(exo_latest_message)
 export(exo_one_small_change)
 export(exo_rebase_i)

R/conflict.R

@@ -0,0 +1,75 @@
+#' "Hey I'd like to see what merge conflicts look like!"
+#'
+#' @description
+#' I made some work in a feature branch and want to merge it.
+#' Meanwhile, the main branch advanced.
+#' Unfortunately someone touched the same file as I did.
+#' Now I need to fix a merge conflict!
+#'
+#' See also <https://happygitwithr.com/git-branches.html#dealing-with-conflicts>.
+#'
+#'
+#' @inheritParams exo_one_small_change
+#'
+#' @section Git commands:
+#' `git merge`.
+#' @return The path to the new project
+#' @export
+#'
+#' @examplesIf interactive()
+#' parent_path <- withr::local_tempdir()
+#' path <- exo_conflict(parent_path = parent_path)
+exo_conflict <- function(parent_path) {
+
+  path <- file.path(parent_path, "conflict")
+
+  withr::local_options(usethis.quiet = TRUE)
+
+  dir_create(path)
+  original_dir <- getwd()
+
+  withr::local_dir(path)
+  gert::git_init()
+
+  file.copy(
+    system.file("exo_conflict-Rprofile.R", package = "saperlipopette"),
+    ".Rprofile"
+  )
+
+  create_project(path = getwd())
+  # Ignore Rproj that might otherwise get edited when we open the project
+  rproj <- fs::dir_ls(glob = "*.Rproj")
+  usethis::local_project(getwd(), force = TRUE)
+  usethis::use_git_ignore(rproj)
+  usethis::use_git_ignore(".Rprofile")
+  gert::git_add("*")
+  git_commit("First commit")
+
+  new_script <- file.path("R", "script.R")
+  fs::file_create(new_script)
+  script_lines <- c("a <- 1", "b <- 2")
+  brio::write_lines(text = script_lines, path = new_script)
+  gert::git_add(new_script)
+  git_commit("feat: add script")
+
+
+  gert::git_branch_create("feature")
+  brio::write_lines(text = c("a <- 10", "b <- 2", "c <- 3"), path = new_script)
+  gert::git_add(new_script)
+  git_commit("feat: improve script")
+
+  if ("main" %in% gert::git_branch_list()[["name"]]) {
+    gert::git_branch_checkout("main")
+  } else {
+    gert::git_branch_checkout("master")
+  }
+  brio::write_lines(text = c("a <- 11", "b <- 2"), path = new_script)
+  gert::git_add(new_script)
+  git_commit("feat: amend script")
+
+  usethis::local_project(original_dir, force = TRUE)
+
+  cli::cli_alert_info("Follow along in {path}!")
+
+  return(path)
+}

_pkgdown.yml

@@ -16,6 +16,7 @@ reference:
   contents:
   - exo_split_changes
   - exo_clean_dir
+  - exo_conflict
   - exo_rebase_i
   - exo_bisect
 - title: All exercises at once

inst/exo_conflict-Rprofile.R

@@ -0,0 +1,22 @@
+if (file.exists("~/.Rprofile")) {
+  base::sys.source("~/.Rprofile", envir = environment())
+}
+
+cli::cli_alert_danger('"I want to merge feature into main."')
+cli::cli_alert_danger("I will need to fix a merge conflict.")
+cli::cli_alert_info("For more help use {.run tip()}")
+
+tip <- function() {
+  cli::cli_li(
+    items = c(
+      "Examine Git history.",
+      "{.code git merge feature} on the default branch",
+      "Edit R/script.R to the desired state, remove conflict markers.",
+      "{.code git add R/script.R}",
+      "{.code git commit}.",
+      "See the merge finalize, you might need to edit a commit message.",
+      "Examine Git history."
+    )
+  )
+
+}

tests/testthat/_snaps/conflict.md

@@ -0,0 +1,9 @@
+# exo_conflict() works
+
+    Code
+      gert::git_log(repo = path)[["commit"]]
+    Output
+      [1] "5d871367c8a247a5e63bd0701d7bce830d1dc614"
+      [2] "2a61d9da6865eb7f7272c9f901f13c1da377a01e"
+      [3] "e227ecc55e421f70b6e30602e6a2eee02aad42e0"
+

tests/testthat/_snaps/create-all.md

@@ -22,6 +22,9 @@
       |   +-- R
       |   +-- bla
       |   \-- fix.txt
+      +-- conflict
+      |   \-- R
+      |       \-- script.R
       +-- latest-message
       |   +-- R
       |   \-- bla

tests/testthat/test-conflict.R

@@ -0,0 +1,7 @@
+test_that("exo_conflict() works", {
+  rlang::local_options(cli.default_handler = function(msg) invisible(NULL))
+  parent_path <- withr::local_tempdir()
+  path <- exo_conflict(parent_path = parent_path)
+  expect_equal(fs::path_file(path), "conflict")
+  expect_snapshot(gert::git_log(repo = path)[["commit"]])
+})