expect-condition.md
In testthat: Unit Testing for R

regexp = NULL checks for presence of error

`null()` did not throw the expected error.

regexp = string matches for error message

"OK" did not throw the expected error.

check type of class and pattern

Code
  expect_error(stop("!"), regexp = 1)
Condition
  Error in `expect_error()`:
  ! `pattern` must be a single string, `NA`, or `NULL`, not the number 1.
Code
  expect_error(stop("!"), class = 1)
Condition
  Error in `expect_error()`:
  ! `class` must be a single string or `NULL`, not the number 1.

message method is called when expecting error

`fb()` threw an unexpected error.
Message: dispatched!
Class:   foobar/rlang_error/error/condition

unused arguments generate a warning

Code
  expect_condition(stop("Hi!"), foo = "bar")
Condition
  Warning in `expect_condition()`:
  Arguments in `...` must be used.
  x Problematic argument:
  * foo = "bar"
  i Did you misspell an argument name?