# Spark Joy by Running Fewer Tests

DevFeed: [Spark Joy by Running Fewer Tests](<https://devfeed.tech/articles/spark-joy-by-running-fewer-tests-1627.md>)

Original publisher: [Read original article](<https://shopify.engineering/spark-joy-by-running-fewer-tests>)

Author: Jessica Xie

Published: 2020-06-11T18:56:00Z

Content type: article

Language: en

Sources: [Shopify Engineering](<https://devfeed.tech/sources/shopify-engineering.md>), [Shopify Engineering - Shopify Engineering](<https://devfeed.tech/sources/shopify-engineering-shopify-engineering.md>)

Topics: [ci](<https://devfeed.tech/topics/ci.md>), [Scalability](<https://devfeed.tech/topics/scalability.md>), [Development](<https://devfeed.tech/topics/development.md>), [Pull Request](<https://devfeed.tech/topics/pull-request.md>), [Shopify](<https://devfeed.tech/topics/shopify.md>), [Code](<https://devfeed.tech/topics/code.md>), [Docker](<https://devfeed.tech/topics/docker.md>)

Tags: [analysis](<https://devfeed.tech/tags/analysis.md>), [bugs](<https://devfeed.tech/tags/bugs.md>), [ci](<https://devfeed.tech/tags/ci.md>), [code](<https://devfeed.tech/tags/code.md>), [containers](<https://devfeed.tech/tags/containers.md>), [developers](<https://devfeed.tech/tags/developers.md>), [docker](<https://devfeed.tech/tags/docker.md>), [docker-containers](<https://devfeed.tech/tags/docker-containers.md>), [performance](<https://devfeed.tech/tags/performance.md>), [pull-request](<https://devfeed.tech/tags/pull-request.md>), [quality-assurance](<https://devfeed.tech/tags/quality-assurance.md>), [scalability](<https://devfeed.tech/tags/scalability.md>), [shopify](<https://devfeed.tech/tags/shopify.md>), [spark](<https://devfeed.tech/tags/spark.md>), [speed](<https://devfeed.tech/tags/speed.md>)

## AI overview

This Shopify Engineering article explains how large test suites can slow development, reduce scalability, and increase intermittent failures. It introduces a dynamic test-selection system intended to make continuous integration faster and more stable by running fewer, more relevant tests.

## Source excerpt

Developers write tests to ensure correctness and allow future changes to be made safely. However, as the number of features grows, so does the number of tests. Tests are a double-edged sword. On one hand, well-written ones catch bugs and maintain a program's stability, but as the code base grows, a high number of tests impedes scalability because they take a long time to run and increase the likelihood of intermittently failing tests.