testthat: expect – R documentation

Pricing

Become an expert in R — Interactive courses, Cheat Sheets, certificates and more!

Get Started for Free

Documentation

testthat

expect

The building block of all expect_ functions

Description

Call expect() when writing your own expectations. See vignette("custom-expectation") for details.

Usage

expect(
  ok,
  failure_message,
  info = NULL,
  srcref = NULL,
  trace = NULL,
  trace_env = caller_env()
)

Arguments

`ok`	`TRUE` or `FALSE` indicating if the expectation was successful.
`failure_message`	Message to show if the expectation failed.
`info`	Character vector continuing additional information. Included for backward compatibility only and new expectations should not use it.
`srcref`	Location of the failure. Should only needed to be explicitly supplied when you need to forward a srcref captured elsewhere.
`trace`	An optional backtrace created by `rlang::trace_back()`. When supplied, the expectation is displayed with the backtrace.
`trace_env`	If `is.null(trace)`, this is used to automatically generate a traceback running from `test_code()`/`test_file()` to `trace_env`. You'll generally only need to set this if you're wrapping an expectation inside another function.

Details

While expect() creates and signals an expectation in one go, exp_signal() separately signals an expectation that you have manually created with new_expectation(). Expectations are signalled with the following protocol:

If the expectation is a failure or an error, it is signalled with base::stop(). Otherwise, it is signalled with base::signalCondition().
The continue_test restart is registered. When invoked, failing expectations are ignored and normal control flow is resumed to run the other tests.

Value

An expectation object. Signals the expectation condition with a continue_test restart.