test: port Composer tests unblocked by mockall, add seams

Port 11 categories of previously-ignored Composer tests now reachable with
the mockall crate: DownloadManager, VCS/Perforce/File downloaders,
VersionSelector, PlatformRepository, Auditor, installer/FilesystemRepository,
RootPackageLoader, util auth/http, commands, and Cache.

Extract test seams additively on concrete structs as *Interface traits
(Runtime, HhvmDetector, VersionGuesser, RepositorySet, Perforce,
BinaryInstaller) plus mock-field seams (Cache, Filesystem); consumers take
trait objects. Mocks are defined locally in the test crates via
mockall::mock!, since automock-generated mocks are cfg(test)-gated and
invisible across the integration-test boundary.

dataProviders are ported in full; tests blocked by unported shims stay
#[ignore] with documented reasons rather than reduced or weakened.

Fix product bugs surfaced by the ports:
- util/github: use the exception code, not the HTTP status, for 401/403
- advisory: serialize empty audit maps as [] to match PHP json_encode
- repository/filesystem and downloader/file: fix RefCell double-borrow panics

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/crates/shirabe/src/factory.rs b/crates/shirabe/src/factory.rs
index 8a97313..2c27015 100644
--- a/crates/shirabe/src/factory.rs
+++ b/crates/shirabe/src/factory.rs
@@ -1270,7 +1270,7 @@ impl Factory {
         guesser: VersionGuesser,
         io: std::rc::Rc<std::cell::RefCell<dyn IOInterface>>,
     ) -> RootPackageLoader {
-        RootPackageLoader::new(rm, config, Some(parser), Some(guesser), Some(io))
+        RootPackageLoader::new(rm, config, Some(parser), Some(Box::new(guesser)), Some(io))
     }
 
     pub fn create(