In rstudio-education/grader: Automated Feedback for Student Exercises in 'learnr' Tutorials

---

title: "script checking" output: learnr::tutorial runtime: shiny_prerendered

---

library(learnr)
library(dplyr)

library(gradethis)
gradethis::gradethis_setup()

The gradethis package provides two main functions to check student code learnr tutorials. You can use:

1. grade_this() to run an expression to that should determine if the result is correct by calling pass() or fail() at some point.
2. grade_this_code() to check that the student's code exactly matches the solution code.

You can also use grade_this() to create your own customized checking code.

Goal

Note: gradethis does not itself calculate a final grade for the student.

Environment

grade_this() has access to more information than the chunk environment.

Extra objects provided by gradethis: .result: The last value from evaluating the user's exercise. Same as learnr's .last_value .solution: The last value from evaluating the solution code

Extra items of information from learnr: .label: Label for exercise chunk .solution_code: Code provided within the "-solution" chunk for the exercise .user_code: Code submitted by the user .check_code: Code provided within the "-check" (or "-code-check") chunk for the exercise .envir_result: The R environment after the execution of user's exercise submission .evaluate_result: The return value from the evaluate::evaluate function .envir_prep: A copy of the R environment before the execution of the exercise submission .last_value: The last value from evaluating the user's exercise submission

(old) Grade Code

log(sqrt(2))

log(sqrt(3))

grade_code()

grade_code()

(old) Grade Result

log(sqrt(2))

grade_result(
  pass_if(~ identical(.result, log(sqrt(3)))),
  fail_if(~ identical(.result, log(sqrt(2))), "change the answer"),
  fail_if(~ TRUE)
)

grade_result(
  pass_if(~ identical(.result, log(sqrt(3)))),
  fail_if(~ identical(.result, log(sqrt(2))), "change the answer"),
  fail_if(~ TRUE)
)

Grade code

4

42

grade_this_code()

grade_this_code()

Script Style

2

4

expected <- 4

grade_this({

  testthat::expect_type(.result, "double")
  checkmate::expect_numeric(.result, lower = 0, upper = 10)

  if (identical(.result, expected)) pass("equals 4!")
  # pass_if_equal(4, MESSAGE)
  # fail_if_equal(4, MESSAGE)

  # testthat::expect_equal(.result, expected)

  fail("{random_encourage()}{maybe_code_feedback()}")
})

expected <- 4

grade_this({

  testthat::expect_type(.result, "double")
  checkmate::expect_numeric(.result, lower = 0, upper = 10)

  if (identical(.result, expected)) pass("equals 4!")
  # pass_if_equal(4, MESSAGE)
  # fail_if_equal(4, MESSAGE)

  # testthat::expect_equal(.result, expected)

  fail("{random_encourage()}{maybe_code_feedback()}")
})

rstudio-education/grader documentation built on July 6, 2023, 8:48 a.m.