Problem:
The magic globals `it`, `describe`, etc., are more trouble than they are
worth.
- Hooking into `after_each` requires `getfenv()` hacks.
- They confuse luals/emmylua, because the top-level `.luarc.json` isn't
merged with `test/.luarc.json` (apparently a luals limitation?)
- They totally defeat discoverability because the user just has to
"know" about the various magic symbols.
So they harm DX, which means they serve no purpose at all.
Solution:
- Expose the test API from `testutil`, so tests can call `t.it()`,
`t.describe()`, etc., in the conventional way.
- Drop `getfenv()` hacks.
- Drop the `setfenv()` injection in `load_chunk`.
- Drop `test/_meta.lua`.
Problem:
`vim.loader.disable` does not conform to `:help dev-name-common` and
`:help dev-patterns`.
Solution:
- Add `enable` parameter to `vim.loader.enable`
- Remove `vim.loader.disable`
- Note the change in `:help news-breaking-dev` (HEAD changes).
- This is not a breaking change (except to "HEAD") because
`vim.loader` is marked "experimental".
previous: 26765e8461
Specifically, functions that are run in the context of the test runner
are put in module `test/testutil.lua` while the functions that are run
in the context of the test session are put in
`test/functional/testnvim.lua`.
Closes https://github.com/neovim/neovim/issues/27004.
Problem: Loading `vim.fs` via the `vim.loader` Lua package loader will
result in a stack overflow due to a cyclic dependency. This may happen
when the `vim.fs` module isn't byte-compiled, i.e. when `--luamod-dev`
is used (#27413).
Solution: `vim.loader` depends on `vim.fs`. Therefore `vim.fs` should
be loaded in advance.
Problem: cache paths are derived by replacing each reserved/filesystem-
path-sensitive char with a `%` char in the original path. With this
method, two different files at two different paths (each containing `%`
chars) can erroneously resolve to the very same cache path in certain
edge-cases.
Solution: derive cache paths by url-encoding the original (path) instead
using `vim.uri_encode()` with `"rfc2396"`. Increment `Loader.VERSION` to
denote this change.
