testthat (version 3.3.0)

inheritance-expectations: Do you expect an S3/S4/R6/S7 object that inherits from this class?

Description

See https://adv-r.hadley.nz/oo.html for an overview of R's OO systems, and the vocabulary used here.

• expect_type(x, type) checks that typeof(x) is type.

• expect_s3_class(x, class) checks that x is an S3 object that inherits() from class

• expect_s3_class(x, NA) checks that x isn't an S3 object.

• expect_s4_class(x, class) checks that x is an S4 object that is() class.

• expect_s4_class(x, NA) checks that x isn't an S4 object.

• expect_r6_class(x, class) checks that x an R6 object that inherits from class.

• expect_s7_class(x, Class) checks that x is an S7 object that S7::S7_inherits() from Class

See expect_vector() for testing properties of objects created by vctrs.

Usage

expect_type(object, type)
expect_s3_class(object, class, exact = FALSE)
expect_s4_class(object, class)
expect_r6_class(object, class)
expect_s7_class(object, class)

Arguments

object

Object to test.

Supports limited unquoting to make it easier to generate readable failures within a function or for loop. See quasi_label for more details.

type

String giving base type (as returned by typeof()).

class

The required type varies depending on the function:

• expect_type(): a string.

• expect_s3_class(): a string or character vector. The behaviour of multiple values (i.e. a character vector) is controlled by the exact argument.

• expect_s4_class(): a string.

• expect_r6_class(): a string.

• expect_s7_class(): an S7::S7_class() object.

For historical reasons, expect_s3_class() and expect_s4_class() also take NA to assert that the object is not an S3 or S4 object.

exact

If FALSE, the default, checks that object inherits from any element of class. If TRUE, checks that object has a class that exactly matches class.

See Also

Other expectations: comparison-expectations, equality-expectations, expect_error(), expect_length(), expect_match(), expect_named(), expect_null(), expect_output(), expect_reference(), expect_silent(), logical-expectations

Examples

x <- data.frame(x = 1:10, y = "x", stringsAsFactors = TRUE)
# A data frame is an S3 object with class data.frame
expect_s3_class(x, "data.frame")
show_failure(expect_s4_class(x, "data.frame"))
# A data frame is built from a list:
expect_type(x, "list")

f <- factor(c("a", "b", "c"))
o <- ordered(f)

# Using multiple class names tests if the object inherits from any of them
expect_s3_class(f, c("ordered", "factor"))
# Use exact = TRUE to test for exact match
show_failure(expect_s3_class(f, c("ordered", "factor"), exact = TRUE))
expect_s3_class(o, c("ordered", "factor"), exact = TRUE)

# An integer vector is an atomic vector of type "integer"
expect_type(x$x, "integer")
# It is not an S3 object
show_failure(expect_s3_class(x$x, "integer"))

# Above, we requested data.frame() converts strings to factors:
show_failure(expect_type(x$y, "character"))
expect_s3_class(x$y, "factor")
expect_type(x$y, "integer")