
library(testthat)

source("user_code.R")
test_that("returns a list with the first letter of each name capitalized", {
  result <- capitalize_first(c("alice", "bob", "charlie"))
  expect_type(result, "list")
  expect_equal(result, list("Alice", "Bob", "Charlie"))
})

test_that("leaves the rest of each name unchanged", {
  result <- capitalize_first(c("alice", "bob", "charlie"))
  expect_equal(result[[1]], "Alice")
  expect_true(substr(result[[1]], 2, nchar(result[[1]])) == "lice")
  expect_true(substr(result[[2]], 2, nchar(result[[2]])) == "ob")
  expect_true(substr(result[[3]], 2, nchar(result[[3]])) == "harlie")
})

test_that("works for lists containing multiple names", {
  result <- capitalize_first(c("eve", "mallory", "trent"))
  expect_equal(result, list("Eve", "Mallory", "Trent"))
})

test_that("handles an empty list by returning an empty list", {
  result <- capitalize_first(character(0))
  expect_type(result, "list")
  expect_equal(length(result), 0)
})

test_main.R

Master the art of writing and using functions in R, from basic syntax to advanced functional programming techniques. This course guides you through creating your own functions, leveraging anonymous functions, and applying functional programming concepts to solve real-world problems in R.

Learn how to define, call, and utilize functions in R, including understanding parameters, return values, and default arguments.

Discover how to use anonymous (inline) functions for concise, on-the-fly operations, and see how they fit into R's functional programming paradigm.

Apply functional programming concepts in R to solve real-world problems, focusing on writing concise, reusable, and efficient code.

Challenge: Real-World Anonymous Functions

Solution

Challenge: Real-World Anonymous Functions

Solution