Lua:
Writing tests

How to:

Lua, being a lightweight yet powerful scripting language, does not include a built-in testing framework. However, third-party libraries like Busted and LuaUnit make testing relatively straightforward. Here, we’ll look at examples using both.

Using Busted

Busted is a popular Lua testing framework that offers a flexible way to write tests. Firstly, install Busted through LuaRocks (Lua’s package manager) with luarocks install busted. Once installed, you can write your tests. Here’s a simple test for a function add that sums two numbers:

-- add.lua
local function add(a, b)
  return a + b
end

return add

-- add_spec.lua
local add = require('add')

describe("Add function", function()
  it("should add two numbers correctly", function()
    assert.are.equal(5, add(2, 3))
  end)
end)

To run the tests, execute busted in your terminal. Sample output for a passing test would look like:

●
1 success / 0 failures / 0 errors / 0 pending : 0.002 seconds

Using LuaUnit

LuaUnit is another testing framework that follows xUnit conventions and is easy to set up. Install LuaUnit via LuaRocks using luarocks install luaunit. Here is how you could write a similar test as above with LuaUnit:

-- add.lua remains the same

-- test_add.lua
luaunit = require('luaunit')
local add = require('add')

function testAdd()
  luaunit.assertEquals(add(2, 3), 5)
end

os.exit(luaunit.LuaUnit.run())

Running this script directly via Lua (lua test_add.lua) will output something like:

.
Ran 1 tests in 0.001 seconds, 1 success, 0 failures

Both Busted and LuaUnit offer extensive features to handle various testing scenarios, including mocking, spying, and asynchronous testing. Choosing between them lies in the specific needs of your project and your personal preference regarding syntax and functionality.