Cargo test change runs doc tests as of 2025-05-17, causing cargo test to fail for examples in docs #216

Issue

Cargo tests are failing in CI pipeline since May 2025.

Cause

A change to cargo in commit rust-lang/cargo@47c911e9e caused doc tests to run by default when the target is different than the host target (which is the case for this repo with .cargo/config.toml specifying the target as thumbv4t-none-eabi).

After this commit was merged, cargo test attempts to run doc test examples as GBA ROMs in mGBA, which fails with "Could not load game. Are you sure it's in the correct format?" because these doc examples are not valid standalone GBA programs.

Working: nightly-2025-05-16 (rust-lang/cargo@056f5f4f3)
Broken: nightly-2025-05-17 (rust-lang/cargo@47c911e9e)

Recommended Solution

Add --lib arg to cargo test in CI workflow to only run unit tests defined in the library, not doc test examples.