[Feature request] support ftplugin

[mrcjkb]

Hey 👋

I was wondering if it would be feasible to support ftplugin workflows.
Specifically, I'd like to be able to add adapters to neotest using files in, e.g.

• ftplugin/haskell.lua
• ftplugin/rust.lua
• ftplugin/java.lua

etc.

At a first glance, it looks like, this could easily be achieved by changing

neotest/lua/neotest/config/init.lua

Line 370 in 73043d6

user_config = vim.tbl_deep_extend("force", default_config, config)

to

user_config = vim.tbl_deep_extend("force", user_config or default_config, config)

Taking this a step further, adapters could potentially self-register themselves in an ftplugin script, if the file that triggered the script to be sourced is a test file.

The caveat to the above approach is that vim.tbl_deep_extend doesn't merge lists,
so the user_config.adapters list would be overwritten.
This could be mitigated either by inserting into the existing table, or by providing a separate register_adapter API.

@rcarriga what are your thoughts?

[rcarriga]

Running setup again introduces complexities elsewhere but I think having a register_adapter method makes sense 😄

[disrupted]

As a workaround I am inserting directly into the adapters list which seems to work fine. #428 (comment)

But I would also be happy if a public API existed to register adapters on demand.