envvar_get.md
In envvar: Make Working with Environment Variables Easier and More Consistent

envvar_get() validates `transform` argument correctly

Code
  envvar_get("HOME", transform = TRUE)
Condition
  Error in `envvar_get()`:
  ! `transform` must be a function

envvar_get() validates `validate` argument correctly

Code
  envvar_get("HOME", validate = TRUE)
Condition
  Error in `envvar_get()`:
  ! `validate` must be a function

envvar_get() errors if variable unset (and `default` is NULL)

Code
  envvar_get("TESTENV_ENVVAR")
Condition
  Error in `envvar_get()`:
  ! Environment variable `TESTENV_ENVVAR` is not set.

envvar_get() shows message if variable unset and `default` given

Code
  expect_equal(envvar_get("TESTENV_ENVVAR", default = "HELLO"), "HELLO")
Message
  i Environment variable `TESTENV_ENVVAR` is not set. Using default value "HELLO".

envvar_get() `validate` function works as expected

Code
  envvar_get("TESTENV_ENVVAR", validate = function(x) nchar(x) == 50L)
Condition
  Error in `envvar_get()`:
  ! "HELLO" is not a valid value for `TESTENV_ENVVAR`

envvar_get_oneof() works as expected

Code
  envvar_get_oneof("TESTENV_ENVVAR", choices = c("APPLE", "DUCK"))
Condition
  Error in `envvar_get()`:
  ! "HELLO" is not a valid value for `TESTENV_ENVVAR`