Could you please provide the content of Chapter 1.1 so I can summarize the programming concept and identify a general domain of usage?


library(testthat)

source("user_code.R")

test_that("variables prices and items are correctly set", {
    expect_equal(
        prices,
        c(Sofa = 340,
            Armchair = 150,
            "Dining table" = 115,
            "Dining chair" = 45,
            Bookshelf = 160)
    )

    expect_equal(
        items,
        c("Sofa",
            "Armchair",
            "Dining table",
            "Dining chair",
            "Bookshelf")
    )

    expect_equal(names(prices), items)
})

test_that("Armchair price equals 150", {
    expect_equal(prices[["Armchair"]], 150)
})

test_that("output of individual references matches expected", {
    out_armchair <- capture.output(prices["Armchair"])
    expect_true(any(grepl("150", out_armchair)))
    expect_true(any(grepl("Armchair", out_armchair)))

    out_3_4 <- capture.output(prices[c(3,4)])
    expect_true(any(grepl("Dining table", out_3_4)))
    expect_true(any(grepl("115", out_3_4)))
    expect_true(any(grepl("Dining chair", out_3_4)))
    expect_true(any(grepl("45", out_3_4)))
})

Chapter 1.1

Solution