implement tutorial_package_dependencies()

NAMESPACE

@@ -40,6 +40,7 @@ export(run_tutorial)
 export(safe)
 export(safe_env)
 export(tutorial)
+export(tutorial_dependencies)
 export(tutorial_html_dependency)
 export(tutorial_options)
 import(rmarkdown)

NEWS.md

@@ -5,6 +5,8 @@ learnr 0.10.0.9000 (unreleased)
 
 ## Minor new features and improvements
 
+* `learnr` gained the function `learnr::tutorial_dependencies()`, used to enumerate a tutorial's R package dependencies. Front-ends can use this to ensure a tutorial's dependencies are satisfied before attempting to run that tutorial.
+
 * Include vignette about publishing learnr tutorials on shinyapps.io
 
 * `learnr`'s built-in tutorials now come with a description as part of the YAML header, with the intention of this being used in front-end software that catalogues available `learnr` tutorials on the system. ([#312](https://github.com/rstudio/learnr/issues/312))

R/dependencies.R

@@ -0,0 +1,19 @@
+
+#' List Tutorial Dependencies
+#'
+#' List the \R packages required to run a particular tutorial.
+#'
+#' @param name The tutorial name.
+#' @param package The \R package providing the tutorial.
+#'
+#' @export
+tutorial_dependencies <- function(name, package) {
+
+  # resolve tutorial path
+  dir <- get_tutorial_path(name, package)
+
+  # enumerate tutorial package dependencies
+  deps <- renv::dependencies(dir, quiet = TRUE)
+  sort(unique(deps$Package))
+
+}

tests/testthat/test-dependency.R

@@ -6,3 +6,7 @@ test_that("tutor html dependencies can be retreived", {
   expect_equal(dep$name, "tutorial")
 })
 
+test_that("tutorial package dependencies can be enumerated", {
+  packages <- tutorial_dependencies("ex-data-summarise", "learnr")
+  expect_true("tidyverse" %in% packages)
+})