Unit test execution in docker container

[Shai-tan]

Hello,
First of all, thank you so much for this wonderful plugin. I had been looking for the capability to run my unit tests without exiting my favorite neovim editor for a long time.

Unfortunately, the development environment of my professional project requires executing the unit tests inside a Docker container instance. As a consequence, after the delegated execution, it is required to use a report in file format to retrieve the execution results. This solution is less elegant than your wrapping of the python script from Lua but I have found no other way.
Additionally, the default report format of pytest is not easy to parse in Lua, which is why I have used the python module pytest-json. The report is parsed to provide the result to the neotest root plugin.

To integrate all of this into your solution, I have added a few configuration properties to your plugin to be able to determine when a docker instance must be used and if so, which instance.

• The use_docker parameter allows the plugin to build the command to launch locally so test execution happens in the docker instance. In the following example, this parameter is a static value but it could also be replaced by a function to allow conditional "dockerization".

• The container parameter provides the name of the container to use for test execution. This parameter can also be a function to dynamically determine the name of the container.

For example, in the following configuration, I use the directory path as discriminator.

     require("neotest").setup({
         adapters = {
             require("neotest-python")({
                 dap = { justMyCode = false },
                 runner = "pytest",
                 use_docker = true,
                 container = function ()
                     local path = vim.loop.cwd()
                     if path ~= nil then
                         if string.find(path, '/dir1') then
                             return 'container-1'
                         elseif string.find(path, '/dir2') then
                             return 'container-2'
                         end
                     end
                     return ''
                 end
             }),
         },
     })

Feel free to say if something looks wrong to you. I am a complete beginner with Lua language and there are many things I might have missed.