Tests: several test files are never compiled/run (silent coverage gap)

[Zorlin]

Problem

Several test files exist under tests/ but are not declared in their parent mod.rs, so Cargo never compiles or runs them. They pass silently as zero-coverage dead weight. The symptom that surfaced this: create_test_run_state in tests/common/mod.rs was flagged `dead_code` — not because it's unused, but because all of its callers are orphaned.

Confirmed orphans

Parent mod.rs files are missing entries for these existing test files:

mod.rs	Declares	Missing (orphaned files)
tests/connection/mod.rs	command	cache.rs, connection.rs, factory.rs, local.rs, ssh.rs
tests/modules/packages/mod.rs	apt, homebrew, yum_dnf	pacman.rs, zypper.rs
tests/playbooks/mod.rs	(others)	context.rs, traversal.rs, visitor.rs

How to verify

# this currently exits 0 even though the files above are never run:
cargo test

After wiring a file in (e.g. adding mod pacman; to tests/modules/packages/mod.rs), the compiler will tell you immediately whether it still builds — some of these orphaned files may have bit-rotted against current APIs.

Suggested fix

1. Add the missing mod declarations to the three mod.rs files above.
2. Run cargo test and fix any compile failures in the newly-included files (they've been dark, so expect some drift).
3. Do a broader audit for other orphans — the detection is name-based and can false-negative when a file's basename collides with a directory that is mod'd elsewhere (e.g. connection.rs vs the connection/ dir).

[Zorlin]

Update: landed the one free win — tests/playbooks/traversal.rs is now wired into tests/playbooks/mod.rs (3 RunState tests, all passing) via #14.

The other ~9 orphaned suites are deferred — wiring them in revealed they're heavily bit-rotted against evolved APIs (not just plumbing):

• 62 compile errors + runtime failures: connection.rs (10), visitor.rs (22), pacman.rs (9), ssh.rs (8), cache.rs (8), plus local/factory/zypper (1–2 each).
• Removed/changed APIs: CacheEntry is gone (cache.rs tests removed internals — may be obsolete), PacmanAction is now private, the Connection trait gained Send + Sync + fetch_file, Inventory::add_host is gone, and Role's YAML format changed (context.rs 1 failing test).

Resurrecting these is real test-rewriting (with update-vs-delete calls), so it's parked rather than blocking v0.5.0. Keeping this issue open for the future pass.

Tip for whoever picks it up: orphaned files aren't reached by cargo fmt (rustfmt follows the module tree), so wiring one in can surface unformatted code — run cargo fmt after adding the mod line.