Merge branch 'master' into wch-shinytest

* master:
  Disable completion of R code inside quotes, closes #401 (#413)
  Bump version (#414)
  Save tutorial output to temp folder when tutorial folder does not have write permissions (#412)
  Throw an informative error if an exercise chunk is NULL (#411)
  Remove outdated exercise option
  Checking for exercise errors (#403)

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: learnr
 Type: Package
 Title: Interactive Tutorials for R
-Version: 0.10.1.9004
+Version: 0.10.1.9005
 Authors@R: c(
   person("Barret", "Schloerke", role = c("aut", "cre"), email = "barret@rstudio.com",
         comment = c(ORCID = "0000-0001-9986-114X")),

NEWS.md

@@ -7,12 +7,14 @@ learnr (development version)
   1. `id` - a randombly generated identifier that can be used to align with the associated `exercise_result` event.
   2. `time_elapsed` - the time required to run the exercise (in seconds)
   3. `timeout_exceeded` - indicates whether the exercise was interrupted due to an exceeded timeout. May be `NA` for some platforms/evaluators if that information is not known or reported. ([#337](https://github.com/rstudio/learnr/pull/337))
+* If a `-code-check` chunk returns feedback for an exercise submission, the result of the exercise is no longer displayed for a correct answer (only the feedback is displayed). If both the result and feedback should be displayed, all checking should be performed in a `-check` chunk (i.e., don't provide a `-code-check` chunk). ([#403](https://github.com/rstudio/learnr/pull/403))
 
 ## New features
 
 * Introduced "setup chunk chaining", which allows a setup chunk to depend on another setup chunk and so on, forming a chain of setup code that can be used for exercises via `exercise.setup`. Run `run_tutorial("setup-chunks", "learnr")` for a demo. ([#390](https://github.com/rstudio/learnr/pull/390))
 * Introduced an [experimental](https://www.tidyverse.org/lifecycle/#experimental) function `external_evaluator()` which can be used to define an exercise evaluator that runs on a remote server and is invoked via HTTP. This allows all exercise execution to be performed outside of the Shiny process hosting the learnr document. ([#345](https://github.com/rstudio/learnr/pull/345), [#354](https://github.com/rstudio/learnr/pull/354))
 * For the "forked" evaluator (the default used on Linux), add a limit to the number of forked exercises that learnr will execute in parallel. Previously, this was uncapped, which could cause a learnr process to run out of memory when an influx of traffic arrived. The default limit is 3, but it can be configured using the `tutorial.max.forked.procs` option or the `TUTORIAL_MAX_FORKED_PROCS` environment variable. ([#353](https://github.com/rstudio/learnr/pull/353))
+* Added a new `tutorial_options()`, namely `exercise.error.checker`, for customizing feedback when exercise submission code produces an evaluation error. This option accepts a function with the same arguments as `exercise.checker`. Use `gradethis::grade_learnr_error()` for a sensible default for this option. ([#403](https://github.com/rstudio/learnr/pull/403))
 * Added an event handler system, with the functions `event_register_handler()` and `one_time()`. There is also a new event `"section_viewed"`, which is triggered when a new section becomes visible. ([#398](https://github.com/rstudio/learnr/pull/398))
 * Previously, when a question submission was reset, it would be recorded as a `"question_submission"` event with the value `reset=TRUE`. Now it a separate event, `"reset_question_submission"`. ([#398](https://github.com/rstudio/learnr/pull/398))
 
@@ -22,7 +24,7 @@ learnr (development version)
 * Added a `restore` flag on `exercise_submitted` events which is `TRUE` if the exercise is being restored from a previous execution, or `FALSE` if the exercise is being run interactively.
 * Add `label` field to the `exercise_hint` event to identify for which exercise the user requested a hint. ([#377](https://github.com/rstudio/learnr/pull/377))
 * Added `include=FALSE` to setup chunks to prevent exercises from printing out messages or potential code output for those setup chunks. ([#390](https://github.com/rstudio/learnr/pull/390))
-* Added error handling when user specificies a non-existent label for `exercise.setup` option with an error message. ([#390](https://github.com/rstudio/learnr/pull/390))
+* Added error handling when user specifies a non-existent label for `exercise.setup` option with an error message. ([#390](https://github.com/rstudio/learnr/pull/390))
 * We no longer forward the checker code to browser (in html), but instead cache it. ([#390](https://github.com/rstudio/learnr/pull/390))
 * We no longer display an invisible exercise result warning automatically. Instead, authors must set the exercise chunk option `exercise.warn_invisible = TRUE` to display an invisible result warning message. ([#373](https://github.com/rstudio/learnr/pull/373))
 
@@ -31,6 +33,9 @@ learnr (development version)
 * Properly enforce time limits and measure exercise execution times that exceed 60 seconds ([#366](https://github.com/rstudio/learnr/pull/366), [#368](https://github.com/rstudio/learnr/pull/368))
 * Fixed unexpected behavior for `question_is_correct.learnr_text()` where `trim = FALSE`. Comparisons will now happen with the original input value, not the `HTML()` formatted answer value. ([#376](https://github.com/rstudio/learnr/pull/376))
 * Fixed exercise progress spinner being prematurely cleared. ([#384](https://github.com/rstudio/learnr/pull/384))
+* Updated `run_tutorial()` to render tutorials in a temp directory if the R user does not have write permissions. ([#347](https://github.com/rstudio/learnr/issues/347))
+* An informative error is now thrown when an exercise chunk's body contains nothing, which lets the tutorial author know that something (e.g., empty line(s)) must be present in the chunk body for it to be rendered as an exercise. ([#410](https://github.com/rstudio/learnr/issues/410)) ([#172](https://github.com/rstudio/learnr/issues/172))
+* When `exercise.completion=TRUE`, completion is no longer performed inside of quotes. This (intentionally) prevents the student from being able to list files on the R server ([#401](https://github.com/rstudio/learnr/issues/401)).
 
 learnr 0.10.1
 ===========

R/evaluators.R

@@ -18,7 +18,7 @@ inline_evaluator <- function(expr, timelimit, ...) {
         error = function(e) {
           # TODO: could grepl the error message to determine if the error was due
           # to an exceeded timeout.
-          error_result(e$message, timeout_exceeded = NA)
+          exercise_result_error(e$message, timeout_exceeded = NA)
         }
       )
     },
@@ -111,7 +111,7 @@ setup_forked_evaluator_factory <- function(max_forked_procs){
 
           # check if it's an error and convert it to an html error if it is
           if(inherits(result, "try-error"))
-            result <<- error_result(result, timeout_exceeded = FALSE)
+            result <<- exercise_result_error(result, timeout_exceeded = FALSE)
 
           TRUE
         }
@@ -126,7 +126,7 @@ setup_forked_evaluator_factory <- function(max_forked_procs){
           running_exercises <<- running_exercises - 1
 
           # return error result
-          result <<- error_result(timeout_error_message(), timeout_exceeded = TRUE)
+          result <<- exercise_result_timeout()
           TRUE
         }
 
@@ -244,7 +244,7 @@ internal_external_evaluator <- function(
 
             print("Error submitting external exercise:")
             print(err)
-            result <<- error_result("Error submitting external exercise. Please try again later")
+            result <<- exercise_result_error("Error submitting external exercise. Please try again later")
           }
 
           curl::curl_fetch_multi(url, handle = handle, done = done_cb, fail = fail_cb, pool = pool)
@@ -280,7 +280,7 @@ internal_external_evaluator <- function(
           },
           onRejected = function(err){
             print(err)
-            result <<- error_result("Error initiating session for external requests. Please try again later")
+            result <<- exercise_result_error("Error initiating session for external requests. Please try again later")
           }
         )
       },