Add use_snapshot()

NAMESPACE

@@ -166,6 +166,7 @@ export(use_rmarkdown_template)
 export(use_roxygen_md)
 export(use_rstudio)
 export(use_rstudio_preferences)
+export(use_snapshot)
 export(use_spell_check)
 export(use_standalone)
 export(use_template)

NEWS.md

@@ -1,6 +1,7 @@
 # usethis (development version)
 
 * `pr_resume()` (without a specific `branch`) and `pr_fetch()` (without a specific `number`) no longer error when a branch name contains curly braces (#2107, @jonthegeek).
+* `use_snapshot()` is a new function to open a [testthat snapshot file]() corresponding to a given test file or R file (#2156, @jonthegeek).
 
 # usethis 3.2.1
 

R/r.R

@@ -88,6 +88,39 @@ use_test <- function(name = NULL, open = rlang::is_interactive()) {
   invisible(TRUE)
 }
 
+#' Edit the snapshot file associated with an R or test file
+#'
+#' This function opens the snapshot file associated with an R or test file, if
+#' one exists.
+#'
+#' @inheritParams use_r
+#' @param variant An optional subdirectory within the `_snaps/` directory.
+#' @export
+use_snapshot <- function(
+  name = NULL,
+  variant = NULL,
+  open = rlang::is_interactive()
+) {
+  if (!uses_testthat()) {
+    use_testthat_impl()
+  }
+
+  path_root <- proj_path("tests", "testthat", "_snaps")
+  if (!is.null(variant)) {
+    path_root <- path(path_root, variant)
+  }
+  # I can't pass "md" to `compute_name()` because we're fine with them giving us
+  # "R" as the extension here.
+  path <- path(path_root, fs::path_ext_set(compute_name(name), "md"))
+
+  if (!file_exists(path)) {
+    cli::cli_abort("No snapshot file exists for {.arg {name}}.")
+  }
+  edit_file(path, open = open)
+
+  invisible(TRUE)
+}
+
 #' Create or edit a test helper file
 #'
 #' This function creates (or opens) a test helper file, typically
@@ -183,7 +216,11 @@ compute_active_name <- function(path, ext, error_call = caller_env()) {
   path <- proj_path_prep(path_expand_r(path))
 
   dir <- path_dir(proj_rel_path(path))
-  if (!dir %in% c("R", "src", "tests/testthat", "tests/testthat/_snaps")) {
+  if (
+    !dir %in% c("R", "src", "tests/testthat", "tests/testthat/_snaps") &&
+      # This makes sure variants are also supported.
+      !grepl("tests/testthat/_snaps", dir)
+  ) {
     cli::cli_abort(
       "Open file must be code, test, or snapshot.",
       call = error_call

_pkgdown.yml

@@ -56,6 +56,7 @@ reference:
     - use_import_from
     - use_r
     - use_rmarkdown_template
+    - use_snapshot
     - use_spell_check
     - use_test
     - use_test_helper

tests/testthat/_snaps/r.md

@@ -1,3 +1,11 @@
+# use_snapshot() errors for non-existent snapshot file
+
+    Code
+      use_snapshot("foo", open = FALSE)
+    Condition
+      Error in `use_snapshot()`:
+      ! No snapshot file exists for `foo`.
+
 # use_test_helper() creates a helper file
 
     Code

tests/testthat/test-r.R

@@ -10,6 +10,24 @@ test_that("use_test() creates a test file", {
   expect_proj_file("tests", "testthat", "test-foo.R")
 })
 
+test_that("use_snapshot() errors for non-existent snapshot file", {
+  create_local_package()
+  expect_snapshot(
+    error = TRUE,
+    use_snapshot("foo", open = FALSE)
+  )
+})
+
+test_that("use_snapshot() works for existing snapshot file", {
+  create_local_package()
+  path <- proj_path("tests", "testthat", "_snaps", "foo.md")
+  use_directory(path("tests", "testthat", "_snaps"))
+  write_utf8(path, "## Snapshot for foo")
+  expect_no_error(
+    use_snapshot("foo", open = FALSE)
+  )
+})
+
 test_that("use_test_helper() creates a helper file", {
   create_local_package()