Remove exercise.error.checker in favor of exercise.error.check.code a…

…nd -error-check chunks, closes #356

R/exercise.R

@@ -391,20 +391,22 @@ render_exercise <- function(exercise, envir, envir_prep) {
     if (grepl(pattern, msg, fixed = TRUE)) {
       return(exercise_result_timeout())
     }
-    # Run the condition through an error checker (the exercise could be to throw an error!)
-    checker_feedback <- try_checker(
-      exercise, "exercise.error.checker",
-      check_code = exercise$check,
-      envir_result = envir,
-      evaluate_result = evaluate_result,
-      envir_prep = envir_prep,
-      last_value = e
-    )
-    if (is_exercise_result(checker_feedback)) {
-      checker_feedback
-    } else {
-      exercise_result_error(msg)
+    error_check_code <- exercise$error_check %||% exercise$options$exercise.error.check.code
+    if (length(error_check_code)) {
+      # Run the condition through an error checker (the exercise could be to throw an error!)
+      checker_feedback <- try_checker(
+        exercise, "exercise.checker",
+        check_code = error_check_code,
+        envir_result = envir,
+        evaluate_result = evaluate_result,
+        envir_prep = envir_prep,
+        last_value = e
+      )
+      if (is_exercise_result(checker_feedback)) {
+        return(checker_feedback)
+      }
     }
+    exercise_result_error(msg)
   })
 
   if (is_exercise_result(output_file)) {

R/knitr-hooks.R

@@ -275,6 +275,7 @@ install_knitr_hooks <- function() {
         all_chunks <- get_all_chunks(options)
 
         code_check_chunk <- get_knitr_chunk(paste0(options$label, "-code-check"))
+        error_check_chunk <- get_knitr_chunk(paste0(options$label, "-error-check"))
         check_chunk <- get_knitr_chunk(paste0(options$label, "-check"))
         solution <- get_knitr_chunk(paste0(options$label, "-solution"))
 
@@ -294,6 +295,7 @@ install_knitr_hooks <- function() {
         exercise_cache <- list(setup = all_setup_code,
                                chunks = all_chunks,
                                code_check = code_check_chunk,
+                               error_check = error_check_chunk,
                                check = check_chunk,
                                solution  = solution,
                                options = options,

R/options.R

@@ -13,8 +13,8 @@
 #'   number of lines in the code chunk).
 #' @param exercise.checker Function used to check exercise answers
 #'   (e.g., `gradethis::grade_learnr()`).
-#' @param exercise.error.checker Function used to check exercise answers
-#'   (e.g., `gradethis::grade_learnr_error()`).
+#' @param exercise.error.check.code A string containing R code to use for checking
+#'   code when an exercise evaluation error occurs (e.g., `"gradethis::grade_code()"`).
 #' @param exercise.completion Use code completion in exercise editors.
 #' @param exercise.diagnostics Show diagnostics in exercise editors.
 #' @param exercise.startover Show "Start Over" button on exercise.
@@ -25,7 +25,7 @@ tutorial_options <- function(exercise.cap = "Code",
                              exercise.timelimit = 30,
                              exercise.lines = NULL,
                              exercise.checker = NULL,
-                             exercise.error.checker = NULL,
+                             exercise.error.check.code = NULL,
                              exercise.completion = TRUE,
                              exercise.diagnostics = TRUE,
                              exercise.startover = TRUE)
@@ -39,7 +39,7 @@ tutorial_options <- function(exercise.cap = "Code",
   eval(parse(text = sprintf(set_option_code, "exercise.timelimit")))
   eval(parse(text = sprintf(set_option_code, "exercise.lines")))
   eval(parse(text = sprintf(set_option_code, "exercise.checker")))
-  eval(parse(text = sprintf(set_option_code, "exercise.error.checker")))
+  eval(parse(text = sprintf(set_option_code, "exercise.error.check.code")))
   eval(parse(text = sprintf(set_option_code, "exercise.completion")))
   eval(parse(text = sprintf(set_option_code, "exercise.diagnostics")))
   eval(parse(text = sprintf(set_option_code, "exercise.startover")))