test: audit pass — trim redundant tests, cover last-failed with filter

[MatthewMckee4]

Summary

Focused test-suite audit. Three deletions of redundant or convention-violating tests and one added integration test for a real coverage gap.

Changes

Deleted test_fail_fast and test_fail_fast_across_modules in basic.rs — they asserted on stdout.contains(...) instead of using insta_cmd::assert_cmd_snapshot!, and were already covered by test_failfast and test_failfast_multiple_threads.

Deleted the unit-test module in karva_runner/src/orchestration.rs that tested a local effective_workers helper reimplementing the worker-capping formula. It never touched the real run_parallel_tests path — a bug in production code couldn't have failed those tests. The integration test test_parallel_worker_capping already covers the real path end-to-end.

Deleted the two trivial FunctionKind::capitalised() unit tests in karva_python_semantic/src/function_kind.rs.

Added last_failed_with_filter_narrows_rerun_set in it/last_failed.rs, covering the --last-failed + -E combination that had no integration test since the filterset DSL landed in #663.

Follow-ups (bugs found, not fixed here)

karva test --dry-run -E … ignores filter expressions. In crates/karva/src/commands/test/mod.rs the dry-run branch runs collect_tests and prints everything before FiltersetSet::new is constructed.

-qq silent mode is unreachable from the CLI. Verbosity::level() only checks self.quiet > 0 and returns Quiet, so VerbosityLevel::Silent is never produced despite being advertised in help text.

Test Plan

• `just test` passes (808 tests)
• `uvx prek run -a` passes

[codspeed-hq]

Merging this PR will not alter performance

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

✅ 1 untouched benchmark

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_{Comparing test/suite-audit-pass (4a9d34b) with main (c05b0d3)}

[MatthewMckee4]

Superseded by #670