Do agent runs that add no tests end worse?

What it found

Of 621 run records that count tests added, 84 (13.5%) add none, mostly research runs. Within track and recording regime they end partial 4 of 84 times against 16 of 537 for runs that add tests: a +2.6 point difference, permutation p = 0.23, so no detectable effect (only 20 partial outcomes exist, so power is low). They cost less (median $0.56 against $0.99 in research), most likely because they do less. Observational and self-reported; preliminary.

A figure from its own output

Paper, code and results

• README and method
• Experiments and results
• Code
• Tests

More in The software-engineering loop

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Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.