local_mocked_s3_method: Mock S3 and S4 methods

In testthat: Unit Testing for R

Mock S3 and S4 methods

Description

These functions temporarily override S3 or S4 methods. They can mock methods that don't already exist, or temporarily remove a method by setting definition = NULL.

Learn more about mocking in vignette("mocking").

Usage

local_mocked_s3_method(generic, signature, definition, frame = caller_env())

local_mocked_s4_method(generic, signature, definition, frame = caller_env())

Arguments

generic	A string giving the name of the generic.
signature	A character vector giving the signature of the method.
definition	A function providing the method definition, or NULL to temporarily remove the method.
frame	Calling frame which determines the scope of the mock. Only needed when wrapping in another local helper.

Examples

x <- as.POSIXlt(Sys.time())
local({
  local_mocked_s3_method("length", "POSIXlt", function(x) 42)
  length(x)
})

length(x)

testthat documentation built on Jan. 11, 2026, 5:06 p.m.