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, 23 insertions, 0 deletions

diff --git a/crates/shirabe/src/repository/repository_set.rs b/crates/shirabe/src/repository/repository_set.rs
index 393639f..f8514cb 100644
--- a/crates/shirabe/src/repository/repository_set.rs
+++ b/crates/shirabe/src/repository/repository_set.rs
@@ -648,6 +648,29 @@ impl RepositorySet {
     }
 }
 
+/// Seam over `RepositorySet` so consumers (e.g. `VersionSelector`) can receive a mockable
+/// repository set in tests. The concrete `RepositorySet` implements it by delegating to its
+/// inherent methods. New consumers may extend this trait additively.
+pub trait RepositorySetInterface: std::fmt::Debug {
+    fn find_packages(
+        &self,
+        name: &str,
+        constraint: Option<AnyConstraint>,
+        flags: i64,
+    ) -> anyhow::Result<Vec<BasePackageHandle>>;
+}
+
+impl RepositorySetInterface for RepositorySet {
+    fn find_packages(
+        &self,
+        name: &str,
+        constraint: Option<AnyConstraint>,
+        flags: i64,
+    ) -> anyhow::Result<Vec<BasePackageHandle>> {
+        RepositorySet::find_packages(self, name, constraint, flags)
+    }
+}
+
 #[derive(Debug)]
 pub struct SecurityAdvisoriesResult {
     pub advisories: IndexMap<String, Vec<AnySecurityAdvisory>>,