I've found that test-driven development is the fastest way for me to learn a new language. There is no better way to bootstrap the learning process than by figuring out how to cobble together a minimal expectation-based testing framework in the new language. The following is the result of my first hour with Lua.

gistfile1.lua

-- #t behaves strangely with hashtables & nil values
function table_length(t)
  local count = 0
  for _ in pairs(t) do count = count + 1 end
  return count
end

function Test(test, expectation)
  return {
    test = test,
    expectation = expectation,
    run = function(self)
      local result = self.test()
      return self.expectation(result)
    end
  }
end

function TestSuite(tests)
  return {
    run = function(self)
      print("Running test suite...")
      local failed_tests = {}
      for k,v in pairs(self.tests) do 
        local outcome = v:run()
        if outcome then
          io.write(".")
        else
          io.write("-")
          failed_tests[k] = outcome
        end
      end
      print("")
      local failed_count = table_length(failed_tests)
      if failed_count > 0 then
        print(failed_count.." failed test(s): ")
        for k,v in pairs(failed_tests) do 
          io.write(k.." ")
        end
        print("")
      else
        print("Success!")
      end
    end,
    tests = tests
  }
end

tests = {
  simple = Test(
    function()
      return 5
    end,
    function(result)
      return result == 5
    end
  )
}

TestSuite(tests):run()