Snapshot Testing Example

This is a small example project used to demonstrate using snapshot (aka approval) testing and code/mutation coverage as a tool for changing mission-critical software following the Law of System Behaviour:

Given sufficient time and usage,
all observable system behaviour,
intentional or unintentional,
will become depended upon.

See https://jasondecarvalho.substack.com/p/snapshot-testing for my article.

Tools

This project uses

• http4k - a functional toolkit for Kotlin HTTP applications
• PIT for mutation testing
• Arcmutate for improved Kotlin support for PIT
• selfie for snapshot testing

Usage

• ./gradlew test to run the tests
• ./gradlew jacocoTestReport to run JaCoCo. Report: build/reports/jacoco/index.html
• ./gradlew pitest to run PIT. Report: build/reports/pitest/index.html