There are formulae that use resource blocks for stuff that is needed in
test blocks. If a resource is a `.zip` archive, one needs `unzip`
utility in `PATH` to extract it, but its only available at build-time,
so one observes an error like that for example:
```
==> brew test psftools --verbose
Testing psftools
==> Downloading https://www.zone38.net/font/pc8x8.zip
Already downloaded: /github/home/.cache/Homebrew/downloads/ea5f6a485687368ff5bc99e4cc43a49b06e081baa51a97ee6ddcd8d1b82d7963--pc8x8.zip
==> Verifying ea5f6a485687368ff5bc99e4cc43a49b06e081baa51a97ee6ddcd8d1b82d7963--pc8x8.zip checksum
unzip -o /github/home/.cache/Homebrew/downloads/ea5f6a485687368ff5bc99e4cc43a49b06e081baa51a97ee6ddcd8d1b82d7963--pc8x8.zip -d /tmp/d20200304-21389-ui0wr0
Error: psftools: failed
undefined method `shelljoin' for nil:NilClass
```
Of course this issue affects Linux the most, because of higher
probability that the system lacks `unzip` for example.
With this commit, all resource guessed dependencies should be available
at build and test time.
When version is nil, (version <==> other.version) also returns nil
and then the nill object doesn't have a nonzero? method.
I'm not sure what package put me into this state, but, this fix repaired
my environment.
Also, there is probably a more ruby-esque way to do this, but, I'm not a
ruby expert ;-)
- In Homebrew/linuxbrew-core, [we have a Linux-only formula for
`texlive`](https://github.com/Homebrew/linuxbrew-core/tree/master/Formula/texlive.rb).
- When running `brew audit --strict texlive` on Linux, we got the
following messaging:
```
$ brew audit --strict texlive
texlive:
* 'texlive' is blacklisted from homebrew/core.
Error: 1 problem in 1 formula detected
```
- Looking at where this comes from leads to the missing formula
messaging to install `mactex` via Homebrew Cask. The 'blacklisted in
homebrew/core' messaging only applies to macOS where Casks are an option
for users, so let's not surface the audit for `texlive` on Linux.
- We recently removed Azure as a supported CI provider
(Homebrew/homebrew-test-bot PR 325), so `brew test-bot` won't run on
Azure any more.
- Homebrew CI is moving towards GitHub Actions as the standard.
This makes `Tap` consistent with what the installer is doing.
Generally shallow clones get slower and slower (and more and more
pointless) the more they are fetched so don't make sense for our
use-case.
Keep the option around anyway because it's useful for integration tests.
We're not actually using this anywhere and it makes the code
more complicated.
Relatedly, this PR fixes the issue where
`uses_from_macos "python@2" => :build` was valid on macOS but not
on Linux.
- Use the `Formula.cache` and `Cacheable` rather than rolling our own.
- Use keyword arguments instead of `options = {}`
- Improve readability in general
