Runs all test files sequentially, each in its own OS process.

This avoids SQLite's global VFS contention that causes spurious "out of memory" errors when test files run in parallel.

Every file runs with warnings-as-errors: the :test alias in mix.exs adds --warnings-as-errors to each child mix test invocation, so test-file compilation warnings fail that file's run. elixirc_options only gates lib/ — test .exs files compile at test time, so the alias is the only place they can be enforced.

Usage

mix test.seq
mix test.seq --trace
mix test.seq --cover   # per-file .coverdata exports under cover/

With --cover, each file's OS process exports a distinctly named .coverdata (derived from the file path), so runs don't overwrite each other. Merge and publish afterwards, e.g. mix coveralls.github --import-cover cover test/xqlite_test.exs.