inst/tests/test-s3.r

In hadley/roxygen3: In-source documentation for R

context("S3 methods/generics")

test_that("primitive generics detected", {
  expect_true(is_s3_generic("["))
  expect_true(is_s3_method("[.data.frame"))

  expect_true(is_s3_generic("mean"))
  expect_true(is_s3_method("[.default"))

  expect_true(is_s3_generic("c"))
  expect_true(is_s3_method("c.Date"))
})

test_that("non-functions are not generics", {
  a <- TRUE
  b <- NULL
  c <- data.frame()

  expect_false(is_s3_generic("a"))
  expect_false(is_s3_generic("b"))
  expect_false(is_s3_generic("c"))
})

test_that("user defined generics & methods detected", {
  my_method <- function(x) UseMethod("mymethod")
  my_method.character <- function(x) x

  expect_true(is_s3_generic("my_method"))
  expect_true(is_s3_method("my_method.character"))
})

test_that("user defined functions override primitives", {
  c <- function(x) x + 1
  c.test <- function(x) x + 3

  expect_false(is_s3_generic("c"))
  expect_false(is_s3_method("c"))
})