Testing on the Lua track

Run your tests with

$ busted

Refer to Installing Lua locally for installing busted.

Debugging Unit Tests

This guide will show you how to set up VSCode with the Busted test framework and Local Lua Debugger so that you can set breakpoints in both the test spec and the file it is testing, facilitating a straightforward Test Driven Development workflow. This is not canonical, there are many methods that may work but this method will at least get you up and running (note: this has been tested and works on Windows 10 and Ubuntu 20.04).

With all that jargon out of the way let's get started.

You can skip these parts as they only serve to explain the process.

In VSCode remove or disable all the other Lua debugger extensions and install Local Lua Debugger. Then create a custom launch configuration like this:

{
	"name": "Busted",
	"type": "lua-local",
	"request": "launch",
	"program": {
		"command": "busted"
	},
	"cwd": "${workspaceFolder}/${relativeFileDirname}",
	"args": ["${file}"],
	"integratedTerminal": true
}

note: The property integratedTerminal will give a warning stating Property integratedTerminal is not allowed but you can happily ignore this.

The cwd property specifices the current working directory, this is important for resolving paths. By default Exercism installs each exercise into it’s own folder under the folder of the track name. So in the case of Lua it looks like this:

└── Exercism/
    ├── lua/
    │   ├── armstrong-numbers
    │   ├── bank-account
    │   ├── binarysearch
    │   └── etc...
    └── python/
        └── etc...

So when we open VSCode from the /lua folder like so:

C:\users\<username>\Exercism\lua> code .

or

/home/<username>/exercism/lua> code .

VSCode will show each exercise in it's own folder in our workspace. That means we need the launch config to change the current working directory, cwd, to each individual exercise folder. We do this with a combination of the ${workspaceFolder} and the ${relativeFileDirname} VSCode variables.

The args property is what argument should be passed to Busted. In this case we use the variable ${file} to reference the currently open file.

Then add these three lines to the top of the test file for the exercise you are undertaking, named <exercise_name>_spec.lua:

if os.getenv("LOCAL_LUA_DEBUGGER_VSCODE") == "1" then
  require("lldebugger").start()
end

Now when you want to run the tests with the debugger, open the test file and then run the launch configuration you have just created from the Run and Debug (Ctrl+Shift+D) sidebar on the left. If the test file is in focus the launch configuration will run those tests, stopping on breakpoints, and print the output to the DEBUG CONSOLE tab in the integrated terminal on the bottom.

Happy Coding!