testthat: equality-expectations – R documentation

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equality-expectations

Does code return the expected value?

Description

These functions provide two levels of strictness when comparing a computation to a reference value. expect_identical() is the baseline; expect_equal() relaxes the test to ignore small numeric differences.

In the 2nd edition, expect_identical() uses identical() and expect_equal uses all.equal(). In the 3rd edition, both functions use waldo. They differ only in that expect_equal() sets tolerance = testthat_tolerance() so that small floating point differences are ignored; this also implies that (e.g.) 1 and 1L are treated as equal.

Usage

expect_equal(
  object,
  expected,
  ...,
  tolerance = if (edition_get() >= 3) testthat_tolerance(),
  info = NULL,
  label = NULL,
  expected.label = NULL
)

expect_identical(
  object,
  expected,
  info = NULL,
  label = NULL,
  expected.label = NULL,
  ...
)

Arguments

`object, expected`	Computation and value to compare it to. Both arguments supports limited unquoting to make it easier to generate readable failures within a function or for loop. See quasi_label for more details.
`...`	3e: passed on to `waldo::compare()`. See its docs to see other ways to control comparison. 2e: passed on to `compare()`/`identical()`.
`tolerance`	3e: passed on to `waldo::compare()`. If non-`NULL`, will ignore small floating point differences. It uses same algorithm as `all.equal()` so the tolerance is usually relative (i.e. `mean(abs(x - y) / mean(abs(y)) < tolerance`), except when the differences are very small, when it becomes absolute (i.e. `mean(abs(x - y) < tolerance`). See waldo documentation for more details. 2e: passed on to `compare()`, if set. It's hard to reason about exactly what tolerance means because depending on the precise code path it could be either an absolute or relative tolerance.
`info`	Extra information to be included in the message. This argument is soft-deprecated and should not be used in new code. Instead see alternatives in quasi_label.
`label, expected.label`	Used to customise failure messages. For expert use only.

Examples

a <- 10
expect_equal(a, 10)

# Use expect_equal() when testing for numeric equality
## Not run: 
expect_identical(sqrt(2) ^ 2, 2)

## End(Not run)
expect_equal(sqrt(2) ^ 2, 2)

testthat

Unit Testing for R

v3.0.2

MIT + file LICENSE

Authors

Hadley Wickham [aut, cre], RStudio [cph, fnd], R Core team [ctb] (Implementation of utils::recover())

Initial release