test_object: Check R object existence and value

In datacamp/testwhat: Easily write submission correctness tests for R exercises

Check R object existence and value

Description

Check whether a student defined a certain object (correctly)

Usage

check_object(state, name, undefined_msg = NULL, append = TRUE)

check_column(state, col, col_missing_msg = NULL, append = TRUE)

check_element(state, el, el_missing_msg = NULL, append = TRUE)

## S3 method for class 'ObjectState'
check_equal(state, incorrect_msg = NULL,
  append = TRUE, eq_condition = "equivalent", eq_fun = NULL, ...)

## S3 method for class 'ObjectColumnState'
check_equal(state, incorrect_msg = NULL,
  append = TRUE, eq_condition = "equivalent", eq_fun = NULL, ...)

## S3 method for class 'ObjectElementState'
check_equal(state, incorrect_msg = NULL,
  append = TRUE, eq_condition = "equivalent", eq_fun = NULL, ...)

Arguments

state	the state to start from
name	name of the object to test.
undefined_msg	Optional feedback message in case the student did not define the object. A meaningful message is automatically generated if not supplied.
append	Whether or not to append the feedback to feedback built in previous states
col	name of column to check
col_missing_msg	Custom message in case data frame column is missing
el	name of element to check
el_missing_msg	Custom message in case element is messing.
incorrect_msg	Custom feedback message in case the student's object is not the same as in the sample solution.
eq_condition	character string indicating how to compare. See is_equal.
eq_fun	optional argument to specify a custom equality function. The function should take two arguments and always return a single boolean value: TRUE or FALSE.
...	S3 stuff

Examples

## Not run: 

# Example 1
x <- mean(1:3, na.rm = TRUE)

# sct to only check existence of x
ex() %>%
  check_object("x")

# sct to check existence and equality
ex() %>%
  check_object("x") %>%
  check_equal()

# Example 2
df <- data.frame(a = 1:3, b = LETTERS[1:3])

# sct to test column a
ex() %>%
  check_object("df") %>%
  check_column("a") %>%
  check_equal()

# Example 3
lst <- list(a = 1, b = 2)

# sct to test only element b
ex() %>%
  check_object("lst") %>%
  check_element("b") %>%
  check_equal()

# Example 4
today <- Sys.Date()

# sct to check if classes are equal
ex() %>%
  check_object("today") %>%
  check_equal(eq_fun = function(x, y) { all.equal(class(x), class(y)) })

## End(Not run)

datacamp/testwhat documentation built on June 26, 2022, 9:07 a.m.