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Testing and Checking Code in Neovim === ❤️

:pencil: by Jacky Alciné Jacky Alciné :book: an vim post :bookmark: neovim , thoughts , testing , opinion :clock7: written :eyeglasses: about 4 minutes, 764 words :link: Comments - 0 Mention(s) - Permalink

I wrote a bit about moving over to neovim and it got a bit of good reception so I’m deciding to write a bit more on neovim from now on. Also, I totally finished this on an airplane.

There’s been quite a few interesting plugins that’s popped up about neovim. This is going to highlight the capabilities of two plugins in particular; vim-test and neomake.

Understanding neomake

neomake aims to be the Neovim-orientated equivalent of Syntastic. neomake is lacking in a few of the “checkers” that syntastic provides but for my particular use-case, this isn’t a problem nor would it be a permanent one, provided that syntastic checkers and neomake checkers follow a common format in definition.

I won’t go over setting up neomake here; this is a blog post, not a Wiki! I will say that the version of neomake I’m using here is from commit efed015 though and that I’m using a development version of neovim (at version 0.1.5-dev). This should help with scoping version and compatibility with the things mentioned here.

Neomake, by default, does nothing. You have to explicitly set up and tell Neomake when you want it to begin checking for information about files you’d like to check. Setting this up can be as direct as running it right after you’ve saved or read a buffer:

" After a buffer's been saved or read, run :Neomake.
au BufReadPost,BufWritePost * Neomake

The :Neomake editor command just runs with the provided file as its value to pass to the underlying checkers for the buffer’s filetype.

:Neomake [makers]       Run a make command with the current file as input. If
                        no makers are specified, the default makers for the
                        current filetype are used. See neomake-configuration
                        for more on makers.

This part is similar to what syntastic does. The difference here now is how neomake takes advantage of Neovim’s job control. In short, job control in Vim is a means to handle multitasking work in VimScript. This allows neomake to execute as many checkers as possible in the background and report status updates when it’s completed. This is handy for large files or even checkers that can be run using a network.

Understanding vim-test

vim-test is a meta-plugin that aims to do something similar to what neomake in terms of checking files but is geared to be done less automatically. It aims to abstract the different test suites available to a developer as well as the different execution layers one can provide to Vim. It’s a solid plugin for being able to quickly test your code. One interesting feature of vim-test is that it can construct a matcher for the test you’re currently under or a close enough matcher based on the tag of the method/function block you’re currently under. A demonstration of this (from the README):

Image of test matching in Go and Ruby

This is personally useful when I’m working on related projects that live in a parent directory. An example structure of said directory layout would be:

 - api
 - infra
 - web
 - admin

Being able to work from the root directory (acme in this case), jump to a file and just run :TestNearest encourages one to constantly test. But this is only half of the benefit of vim-test.

Sending It Away - Abstracted Runners for vim-test

What keeps me with vim-test is that the how of the test running is abstracted from the tool. The fact that I can have tests run in a separate tmux pane, using Neovim’s :terminal emulation or a custom definition changes how I’ve seen testing with Vim. The component that handles the actual execution of a provided test suite’s command is called a strategy in vim-test. By default, vim-test falls back to the classic :!/:shell approach. Depending on what you set g:test#strategy to, you can have it run in tmux, iTerm’s separate worker support or even externally.

Strategies can allow for flexible execution of tests, even sending them to a remote machine if necessary so that your machine is alleviated of load. This remote execution can be done using transformations.