Prepare shared test inputs once

Produce or download common test inputs once and pass them to the jobs that consume them.

Prompt

Evaluate and apply this CI technique to my repository: Prepare shared test inputs once.

Produce or download common test inputs once and pass them to the jobs that consume them.

Read the technique and its source-backed company examples: https://starsling.dev/ci-playbooks/techniques/reuse-shared-test-inputs.md

Inspect this repository’s CI workflows, build and test commands, dependencies, and recent run timings. Identify where this technique applies and explain the expected benefit using this repository’s evidence.
Measure a baseline from recent comparable runs: elapsed time, queue time, runner minutes and failures where available. If data is unavailable, say what cannot be measured.
Compare relevant company approaches, checking prerequisites, platform differences and tradeoffs. Rank applicable options by evidence, fit and measurable opportunity; do not present company results as predictions for this repo.
Recommend the smallest safe change, show what checks and fallback paths remain, and ASK ME WHICH CHANGE TO APPROVE BEFORE EDITING ANY FILES.
Only after approval, work on a new feature branch, make one reversible change, and open a reviewable pull request. Never merge or push to a default or protected branch.
Keep required checks, test coverage, deployment and release behavior intact. Validate the change and compare equivalent runs where possible; report limitations and what should be monitored after merge.

View all playbooks

How companies used this technique

Read what each company changed and follow the original sources.

Publish test packages once and hand off the registry

Mastra introduced a producer job that publishes required local packages to Verdaccio storage, uploads it, and lets each consumer job download and serve that snapshot.

Use it when: Independent fixture tests repeat the same package publishing and registry preparation.
Before applying it: The producer becomes a shared dependency. Compare its latency plus artifact transfer against repeated work; bind artifacts to the same commit and platform, preserve trust and never fall back silently to public packages.

Download shared test inputs once

Stripe .NET moved its OpenAPI spec and fixture download into one job and passes them to every matrix test job as an artifact, so all lanes test against the same selected spec.

Use it when: Many jobs independently download identical versioned fixtures.
Before applying it: A producer job adds a serial step and transfer time, so a very small download can stay in each job. Keep fixture identity and version selection exact.

How companies used this technique

Publish test packages once and hand off the registry

Download shared test inputs once

Related techniques

Build once and share the output with test shards

Bake stable dependencies into runner images

Cache package downloads and dependency stores

Company Playbooks

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Cache workflow dependencies

Cut repeated test setup

Share setup steps across jobs

Optimize npm installs

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