Test: Check whether a variable is equal to a specified expression

check.variable(
var,
expr,
length = check.all,
dim = check.all,
class = check.all,
values = check.all,
check.all = TRUE,
...,
tol = .Machine$double.eps^0.5, failure.exists = "You have not yet generated the variable {{var}}.", failure.length = "Your variable {{var}} has length {{length_stud}} but it shall have length {{length_sol}}.", failure.dim = "Your variable {{var}} has the wrong dimensions (rows x columns).", failure.class = "Your variable {{var}} has a wrong class. It should be {{class_sol}} but it is {{class_stud}}.", failure.values = "Your variable {{var}} has wrong values.", success.message = "Great, {{var}} has correct {{tests}}.", ps = get.ps(), stud.env = ps$stud.env,
verbose = FALSE,
part = NULL
)

## Arguments

var a the variable name as string an expression that will be evaluated in the student environment and returns the variable shall length be checked (similar dim, class, values) a message that is shown if the variable does not exists (similar the other failure.??? variables) a text that will be added to all failure messages