mini.test: ignore regions in reference_screenshot

[9999years]

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Module(s)

mini.test

Description

I'm working on a Neovim plugin to integrate with a command-line tool broot. To verify its behavior, I'd like to use the expect.reference_screenshot function. Unfortunately, broot includes an absolute path as part of its UI, so I get failures like this when running the tests in CI:

Reference:
--|---------|---------|---------|---------|
01|/Users/wiggles/broot.nvim/tests/data    

Observed:
--|---------|---------|---------|---------|
01|/private/tmp/nix-build-broot.nvim-tests.

It would be nice if I could designate 'volatile' regions of the screenshot like this and have them ignored in the reference_screenshot function.

For instance, here I could ignore the first line.

What do you think?

[echasnovski]

Thanks for the suggestion!

Indeed, having to deal with different paths in local and CI tests is somewhat of a pain. I tend to mock any related functionality in tests. Like if path comes from vim.fn.getcwd(), I'll add vim.fn.getcwd = function() return 'mock/current-dir' end in related test. Not sure how to go with this approach in case of a CLI app though.

Having ignoreable screenshot regions is an approach I didn't think about. It is interesting, but I am not sure about the proper function API here. Some ideas:

• ignore_lines with array of lines to ignore. Seems easy enough to implement.
• ignore_region with a from_line, to_line, from_col, to_col fields. It is relatively easy to implement and document, but only allows ignoring only single contiguous region.
• ignore_regions with array of previous ones. Seems a bit too complicated.

I'll definitely think about this.

[echasnovski]

Thanks again for the suggestion!

This should now be (at least partially) possible with ignore_lines option of expect.reference_screenshot. So something like expect.reference_screenshot(screenshot, path, { ignore_lines = { 2, 3 } }) will compare screenshots but if they don't match on lines 2 or 3 (either in text or highlight attribute), it will still return true.

I figured that only ignoring lines is a reasonable compromise between implementation complexity and covering many use cases.

[9999years]

Thanks!