
library(testthat)

source("user_code.R")
library(testthat)

source("user_code.R")
test_that("function returns a positive integer", {
  out <- count_until_large_random()
  expect_true(is.numeric(out) && out == as.integer(out),
              info = "Returned value should be an integer.")
  expect_gt(out, 0)
})

test_that("function always returns 1 or more", {
  for (i in 1:10) {
    out <- count_until_large_random()
    expect_gte(out, 1)
  }
})

test_that("function stops when number is greater than 0.95", {
  # Mock runif to always return 0.96 on first call
  local({
    old_runif <- runif
    assign('runif', function(n) 0.96, envir = .GlobalEnv)
    on.exit(assign('runif', old_runif, envir = .GlobalEnv))
    out <- count_until_large_random()
    expect_equal(out, 1, info = "Should stop at first attempt when random number > 0.95.")
  })
})

test_that("function counts correct number of attempts", {
  # Mock runif to return sequence: 0.1, 0.3, 0.5, 0.99
  local({
    old_runif <- runif
    vals <- c(0.1, 0.3, 0.5, 0.99)
    pos <- 0
    assign('runif', function(n) { pos <<- pos + 1; vals[pos] }, envir = .GlobalEnv)
    on.exit(assign('runif', old_runif, envir = .GlobalEnv))
    out <- count_until_large_random()
    expect_equal(out, 4, info = "Should return 4 when fourth random number > 0.95.")
  })
})

test_main.R

Master the essentials of control flow in R, including conditional statements, loops, and the powerful apply family of functions. This course is designed for beginners and will guide you through practical, real-world examples to help you write efficient and readable R code.

Learn how to control the flow of your R programs using conditional statements, including if, else, else if, and how to apply logic to vectors.

Master the use of loops in R, including for, while, and repeat, and learn how to optimize your code for efficiency.

Unlock the power of R's apply family functions to perform operations on data structures efficiently and elegantly.

Challenge: Random Number Generator

解答