cask/artifact/pkg: fix type error

[samford]

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When the HOMEBREW_SORBET_RECURSIVE=1 environment variable is set and a cask using the pkg stanza is installed/upgraded, Sorbet will give a type error (Parameter 'env': Expected type T::Hash[String, T.nilable(T.any(PATH, String, T::Boolean))], got T::Hash[String, User]) related to SystemCommand.run!. I looked for usage of User in cask and saw that Cask::Artifact::Pkg.run_installer uses User objects in the env arg to SystemCommand.run!. This resolves the issue by calling #to_s on User.current, to ensure it's a string.

You can replicate this by setting the HOMEBREW_SORBET_RECURSIVE=1 environment variable and installing/upgrading a cask that uses the pkg stanza (e.g., HOMEBREW_SORBET_RECURSIVE=1 brew install cloudflare-warp).

[Copilot]

Pull request overview

Fixes a Sorbet type error in the Cask pkg artifact installer path by ensuring the environment variables passed to SystemCommand.run! are typed as strings.

Changes:

• Convert User.current to a string before populating env: for /usr/sbin/installer.
• Reuse the converted value across LOGNAME/USER/USERNAME to satisfy SystemCommand’s Sorbet signature.

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[p-linnane]

This looks good. The remaining gap seems to be in Library/Homebrew/test/cask/artifact/pkg_spec.rb, since the existing expectation can still pass with a User delegator.

How about something like this in the spec?:

current_user = User.current&.to_s

env: {
  "LOGNAME"  => an_instance_of(String).and(eq(current_user)),
  "USER"     => an_instance_of(String).and(eq(current_user)),
  "USERNAME" => an_instance_of(String).and(eq(current_user)),
}

[samford]

Nice, that seems to do what we're looking for. Added in the latest push 👍

[p-linnane]

This PR should unblock CI here: #22927