Display available tutorials

NAMESPACE

@@ -8,6 +8,7 @@ S3method(mutate_tags,logical)
 S3method(mutate_tags,numeric)
 S3method(mutate_tags,shiny.tag)
 export(answer)
+export(available_tutorials)
 export(duplicate_env)
 export(filesystem_storage)
 export(initialize_tutorial)
@@ -60,5 +61,6 @@ importFrom(shiny,reactive)
 importFrom(shiny,reactiveValues)
 importFrom(shiny,req)
 importFrom(stats,runif)
+importFrom(utils,adist)
 importFrom(utils,getFromNamespace)
 importFrom(withr,with_envvar)

NEWS.md

@@ -15,12 +15,13 @@ learnr 0.10.0 (unreleased)
 
 * Question width will expand to the container width. ([#222](https://github.com/rstudio/learnr/pull/222))
 
+* Available tutorial names will be displayed when no `name` parameter or an incorrect `name` is provided to `run_tutorial()`. ([#234](https://github.com/rstudio/learnr/pull/234))
+
 ## Bug fixes
 
 * Fixed a spurious console warning when running exercises using Pandoc 2.0. ([#154](https://github.com/rstudio/learnr/issues/154))
 
 
-
 learnr 0.9.2
 ===========
 

R/run.R

@@ -15,23 +15,48 @@
 #'   the .Rmd file must exist).
 #'
 #' @seealso \code{\link{safe}}
+#' @rdname run_tutorial
+#' @importFrom utils adist
 #' @export
 run_tutorial <- function(name, package, shiny_args = NULL) {
 
+  possible_tutorials <- available_tutorials(package)
+  pkg_tutorials <- paste0(
+    "Available \"", package, "\" tutorials: ", paste0(paste0("\"", possible_tutorials, "\""), collapse = ", ")
+  )
+
+  if (missing(name)) {
+    message(pkg_tutorials)
+    return(invisible(possible_tutorials))
+  }
+
   # get path to tutorial
   tutorial_path <- system.file("tutorials", name, package = package)
 
   # validate that it's a direcotry
-  if (!utils::file_test("-d", tutorial_path))
-    stop("Tutorial ", name, " was not found in the ", package, " package.")
+  if (!utils::file_test("-d", tutorial_path)) {
+    firstlinesep <- "\t"
+    linesep <- "\n\t"
+    msg <- paste0("Tutorial \"", name, "\" was not found in the \"", package, "\" package.")
+    # if any tutorial names are _close_ tell the user
+    adist_vals <- adist(possible_tutorials, name)
+    if (any(adist_vals <= 3)) {
+      best_match <- possible_tutorials[which.min(adist_vals)]
+      msg <- paste0(
+        msg, linesep,
+        "Did you mean \"", best_match, "\"?"
+      )
+    }
+    stop.(firstlinesep, msg, linesep, pkg_tutorials)
+  }
 
   # provide launch_browser if it's not specified in the shiny_args
   if (is.null(shiny_args))
     shiny_args <- list()
   if (is.null(shiny_args$launch.browser)) {
     shiny_args$launch.browser <- (
       interactive() ||
-      identical(Sys.getenv("LEARNR_INTERACTIVE", "0"), "1")
+        identical(Sys.getenv("LEARNR_INTERACTIVE", "0"), "1")
     )
   }
 
@@ -45,6 +70,35 @@ run_tutorial <- function(name, package, shiny_args = NULL) {
   })
 }
 
+#' @rdname run_tutorial
+#' @export
+available_tutorials <- function(package) {
+
+  if (!file.exists(
+    system.file(package = package)
+  )) {
+    stop.("No package found with name: \"", package, "\"")
+  }
+
+  tutorials_dir <- system.file("tutorials", package = package)
+  if (!file.exists(tutorials_dir)) {
+    stop.("No tutorials found for package: \"", package, "\"")
+  }
+
+  tutorial_folders <- list.dirs(tutorials_dir, full.names = TRUE, recursive = FALSE)
+  names(tutorial_folders) <- basename(tutorial_folders)
+  has_rmd <- vapply(tutorial_folders, FUN.VALUE = logical(1), function(tut_dir) {
+    length(dir(tut_dir, pattern = "\\.Rmd$", recursive = FALSE)) > 0
+  })
+  if (all(!has_rmd)) {
+    stop.("No tutorial .Rmd files found for package: \"", package, "\"")
+  }
+
+  tutorial_names <- tutorial_folders[has_rmd]
+  unique(names(tutorial_names))
+}
+
+
 
 #' Safe R CMD environment
 #'

R/utils.R

@@ -21,6 +21,10 @@ is_localhost <- function(location) {
     FALSE
 }
 
+stop. <- function(...) {
+  stop(..., call. = FALSE)
+}
+
 
 #' Create a duplicate of an environment
 #'

tests/testthat/test-available-tutorials.R

@@ -0,0 +1,15 @@
+
+context("available tutorials")
+
+test_that("Tutorial names are retrieved", {
+
+  expect_error(available_tutorials("not a package"), "No package found")
+  expect_error(available_tutorials("base"), "No tutorials found")
+  expect_true("hello" %in% available_tutorials("learnr"))
+  expect_true("hello" %in% suppressMessages(run_tutorial(package = "learnr")))
+
+  expect_error(run_tutorial("helloo", package = "learnr"), "\"hello\"")
+  expect_error(run_tutorial("doesn't exist", package = "learnr"), "Available ")
+  expect_message(run_tutorial(package = "learnr"), "Available ")
+
+})