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Working with data · 16 / 69

Read a named price

YOUR TASK

Make this happen

3 steps

  1. A map type describes keys and values. Bracket lookup allows a key to come from a variable, unlike dot lookup which names a literal field.

  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.price = function(prices: { [string]: number }, sku: string): number
  return 0
end

lesson.test.lua

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

t.it("uses the requested key", function()
  local s = subject.load()
  t.expect(s.price({ paper = 12, ink = 30 }, "ink")):eq(30)
end)