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Working with data · 15 / 69

Transform every entry

YOUR TASK

Make this happen

3 steps

  1. A transformation produces one output for every input. Convert centimetres to millimetres while preserving array order and leaving the input untouched.

  2. Read the cases in lesson.test.lua, then choose Check solution to see what needs to change.

  3. Update subject.lua until every test passes. Keep the supplied tests unchanged.

Start with Check solution, then use the failures to guide your edits.

Read the starter and tests

subject.lua

exports.millimetres = function(values: { number }): { number }
  return values
end

lesson.test.lua

local t = require("test")
local subject = require("cococo.subject")

t.it("converts all values", function()
  local s = subject.load()
  t.expect(s.millimetres({ 2, 3.5 })):deep_eq({ 20, 35 })
end)

t.it("does not mutate input", function()
  local s = subject.load()
  local input = { 2 }
  s.millimetres(input)
  t.expect(input[1]):eq(2)
end)