Add robot-name exercise (#373)

config.json

@@ -824,6 +824,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 4
+      },
+      {
+        "slug": "robot-name",
+        "name": "Robot Name",
+        "uuid": "445bd3fd-011d-4a8f-aa83-5acc53225679",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 4
       }
     ]
   },

exercises/practice/robot-name/.docs/instructions.md

@@ -0,0 +1,14 @@
+# Instructions
+
+Manage robot factory settings.
+
+When a robot comes off the factory floor, it has no name.
+
+The first time you turn on a robot, a random name is generated in the format of two uppercase letters followed by three digits, such as RX837 or BC811.
+
+Every once in a while we need to reset a robot to its factory settings, which means that its name gets wiped.
+The next time you ask, that robot will respond with a new random name.
+
+The names must be random: they should not follow a predictable sequence.
+Using random names means a risk of collisions.
+Your solution must ensure that every existing robot has a unique name.

exercises/practice/robot-name/.meta/config.json

@@ -0,0 +1,18 @@
+{
+  "authors": [
+    "erikschierboom"
+  ],
+  "files": {
+    "solution": [
+      "robot-name.R"
+    ],
+    "test": [
+      "test_robot-name.R"
+    ],
+    "example": [
+      ".meta/example.R"
+    ]
+  },
+  "blurb": "Manage robot factory settings.",
+  "source": "A debugging session with Paul Blackwell at gSchool."
+}

exercises/practice/robot-name/.meta/example.R

@@ -0,0 +1,20 @@
+new_robot <- function() {
+  structure(
+    list(
+      name = random_name()
+    ),
+    class = "robot"
+  )
+}
+
+reset_robot <- function(robot) {
+  robot$name <- random_name()
+  robot
+}
+
+random_name <- function() {
+  paste0(
+    c(sample(LETTERS, 2, replace = TRUE), sample(0:9, 3, replace = TRUE)),
+    collapse = ""
+  )
+}

exercises/practice/robot-name/robot-name.R

@@ -0,0 +1,7 @@
+new_robot <- function() {
+
+}
+
+reset_robot <- function(robot) {
+
+}

exercises/practice/robot-name/test_robot-name.R

@@ -0,0 +1,29 @@
+source("./robot-name.R")
+library(testthat)
+
+test_that("Robot has a class", {
+  robot <- new_robot()
+  expect_s3_class(robot, "robot")
+})
+
+test_that("Robot has a name", {
+  robot <- new_robot()
+  expect_match(robot$name, "^[A-Z]{2}\\d{3}$")
+})
+
+test_that("Name is the same each time", {
+  robot <- new_robot()
+  expect_equal(robot$name, robot$name)
+})
+
+test_that("Two different robots have different names", {
+  robot1 <- new_robot()
+  robot2 <- new_robot()
+  expect_true(robot1$name != robot2$name)
+})
+
+test_that("Can reset the name", {
+  robot <- new_robot()
+  reset_robot <- reset_robot(robot)
+  expect_true(robot$name != reset_robot$name)
+})