Rewrite assertions before test execution

[MatthewMckee4]

Summary

Rewrite assertions while importing collected test modules so message-less AssertionError values include the evaluated expression. Fixes #1082.

Test Plan

cargo insta test -p karva --accept --test-runner nextest and uvx prek run -a.

[github-actions]

❌ Merging this PR may alter performance

Baseline: main (ce8ff7d). Candidate: PR (59f0d35). Each benchmark compares median CLI wall time on one GitHub Actions runner, alternating install order. Runs warm the duration cache before measuring and include default per-test status output. Lower is better.

⚡ 0 improved benchmarks
❌ 13 regressed benchmarks
✅ 1 unchanged benchmark

Warning

Benchmark regressions were detected. Review the wall-time changes before merging.

Performance Changes

	Mode	Benchmark	Base	Head	Change	Runs
❌	WallTime	requests	16.040 s	16.882 s	+5.3%	4
❌	WallTime	fastapi	6.768 s	8.588 s	+26.9%	7
❌	WallTime	httpx	9.137 s	9.781 s	+7.1%	7
❌	WallTime	h11	395.1 ms	566.6 ms	+43.4%	21
❌	WallTime	markupsafe	252.8 ms	272.5 ms	+7.8%	21
❌	WallTime	itsdangerous	268.6 ms	289.0 ms	+7.6%	21
❌	WallTime	blinker	287.6 ms	308.4 ms	+7.2%	21
❌	WallTime	jinja	574.5 ms	796.7 ms	+38.7%	21
❌	WallTime	installer	382.1 ms	403.0 ms	+5.5%	21
❌	WallTime	tomlkit	655.6 ms	940.5 ms	+43.5%	15
❌	WallTime	outcome	281.2 ms	301.7 ms	+7.3%	21
❌	WallTime	pluggy	333.6 ms	483.8 ms	+45.1%	21
❌	WallTime	werkzeug	9.039 s	10.267 s	+13.6%	7

All benchmark scores

	Mode	Benchmark	Base	Head	Change	Runs
❌	WallTime	requests	16.040 s	16.882 s	+5.3%	4
❌	WallTime	fastapi	6.768 s	8.588 s	+26.9%	7
❌	WallTime	httpx	9.137 s	9.781 s	+7.1%	7
❌	WallTime	h11	395.1 ms	566.6 ms	+43.4%	21
❌	WallTime	markupsafe	252.8 ms	272.5 ms	+7.8%	21
✅	WallTime	sniffio	269.1 ms	268.5 ms	-0.2%	21
❌	WallTime	itsdangerous	268.6 ms	289.0 ms	+7.6%	21
❌	WallTime	blinker	287.6 ms	308.4 ms	+7.2%	21
❌	WallTime	jinja	574.5 ms	796.7 ms	+38.7%	21
❌	WallTime	installer	382.1 ms	403.0 ms	+5.5%	21
❌	WallTime	tomlkit	655.6 ms	940.5 ms	+43.5%	15
❌	WallTime	outcome	281.2 ms	301.7 ms	+7.3%	21
❌	WallTime	pluggy	333.6 ms	483.8 ms	+45.1%	21
❌	WallTime	werkzeug	9.039 s	10.267 s	+13.6%	7

[github-actions]

❌ Merging this PR may increase memory usage

Baseline: main (ce8ff7d). Candidate: PR (59f0d35). Each benchmark compares median peak RSS for the installed Karva CLI on one GitHub Actions runner, alternating install order. Runs warm the duration cache before measuring and are configured per project. Lower is better.

⚡ 0 improved benchmarks
❌ 10 regressed benchmarks
✅ 4 unchanged benchmarks

Warning

Benchmark regressions were detected. Review the peak-memory changes before merging.

Performance Changes

	Mode	Benchmark	Base	Head	Change	Runs
❌	Memory	requests	60.2 MiB	69.3 MiB	+15.0%	4
❌	Memory	fastapi	146.1 MiB	148.0 MiB	+1.3%	7
❌	Memory	httpx	81.0 MiB	81.9 MiB	+1.1%	7
❌	Memory	h11	53.1 MiB	55.3 MiB	+4.0%	21
❌	Memory	markupsafe	41.9 MiB	42.9 MiB	+2.3%	21
❌	Memory	itsdangerous	44.1 MiB	44.8 MiB	+1.5%	21
❌	Memory	jinja	56.9 MiB	58.3 MiB	+2.4%	21
❌	Memory	tomlkit	49.1 MiB	50.0 MiB	+2.0%	15
❌	Memory	pluggy	45.9 MiB	47.6 MiB	+3.7%	21
❌	Memory	werkzeug	135.8 MiB	138.7 MiB	+2.1%	7

All benchmark scores

	Mode	Benchmark	Base	Head	Change	Runs
❌	Memory	requests	60.2 MiB	69.3 MiB	+15.0%	4
❌	Memory	fastapi	146.1 MiB	148.0 MiB	+1.3%	7
❌	Memory	httpx	81.0 MiB	81.9 MiB	+1.1%	7
❌	Memory	h11	53.1 MiB	55.3 MiB	+4.0%	21
❌	Memory	markupsafe	41.9 MiB	42.9 MiB	+2.3%	21
✅	Memory	sniffio	47.6 MiB	47.9 MiB	+0.6%	21
❌	Memory	itsdangerous	44.1 MiB	44.8 MiB	+1.5%	21
✅	Memory	blinker	46.9 MiB	47.2 MiB	+0.6%	21
❌	Memory	jinja	56.9 MiB	58.3 MiB	+2.4%	21
✅	Memory	installer	48.6 MiB	48.9 MiB	+0.6%	21
❌	Memory	tomlkit	49.1 MiB	50.0 MiB	+2.0%	15
✅	Memory	outcome	48.6 MiB	48.8 MiB	+0.5%	21
❌	Memory	pluggy	45.9 MiB	47.6 MiB	+3.7%	21
❌	Memory	werkzeug	135.8 MiB	138.7 MiB	+2.1%	7

[github-actions]

✅ No diagnostic changes

Test result comparison

Project	Previous	New
requests	❌ 149 pass · 0 fail · 6 error · 12 skip	❌ 149 pass · 0 fail · 6 error · 12 skip
fastapi	❌ 1596 pass · 7 fail · 434 error · 1 skip	❌ 1596 pass · 7 fail · 434 error · 1 skip
httpx	❌ 1022 pass · 50 fail · 54 error · 1 skip	❌ 1022 pass · 50 fail · 54 error · 1 skip
h11	✅ 78 pass · 0 fail · 0 error · 0 skip	✅ 78 pass · 0 fail · 0 error · 0 skip
markupsafe	❌ 0 pass · 0 fail · 26 error · 0 skip	❌ 0 pass · 0 fail · 26 error · 0 skip
sniffio	✅ 3 pass · 0 fail · 0 error · 1 skip	✅ 3 pass · 0 fail · 0 error · 1 skip
itsdangerous	✅ 10 pass · 0 fail · 0 error · 0 skip	✅ 10 pass · 0 fail · 0 error · 0 skip
blinker	✅ 25 pass · 0 fail · 0 error · 0 skip	✅ 25 pass · 0 fail · 0 error · 0 skip
jinja	❌ 135 pass · 0 fail · 16 error · 0 skip	❌ 135 pass · 0 fail · 16 error · 0 skip
installer	✅ 20 pass · 0 fail · 0 error · 0 skip	✅ 20 pass · 0 fail · 0 error · 0 skip
tomlkit	✅ 332 pass · 0 fail · 0 error · 0 skip	✅ 332 pass · 0 fail · 0 error · 0 skip
outcome	✅ 10 pass · 0 fail · 0 error · 0 skip	✅ 10 pass · 0 fail · 0 error · 0 skip
pluggy	❌ 124 pass · 1 fail · 27 error · 0 skip	❌ 124 pass · 1 fail · 27 error · 0 skip
werkzeug	❌ 728 pass · 3 fail · 0 error · 0 skip	❌ 728 pass · 3 fail · 0 error · 0 skip