Here is a quick developer experience win: Only run the unit tests for the modules with changes against a base branch.
We’ll build upon the Simple Modularization post. In that repo, we added a lane to run all the tests of all the modules. Now, we will add a lane to only run the tests for the modules with changes, to speed up the process and improve the developer experience.
This will also save up precious CI time, as developers will get test failures on their machines, without the need to wait for the CI to run all the tests.
Table of Contents
Gathering the changed packages
The first thing we need to do, is to add a method to check the diff between the current branch and the base branch.
We can do this by executing a really simple shell command:
git diff --name-only origin/main
This will return a list of files that have changed between the current branch and the base branch.
Example:
Packages/CoreLayer/APIModels/Sources/APIModels/APIModel.swift
Then we need to extract the Scheme for the changed package and store all the changes packages.
Running the tests
For this, we can leverage the test_all_packages lane that we already have, but modify it to receive an array of packages.
Check the complete diff in this commit.
> bundle exec fastlane test_changed_packages
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--- Step: shell command ---
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🔍 Found 1 changed packages: CoreLayer/APIModels
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--- Step: Switch to ios test_all_packages lane ---
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Cruising over to lane 'ios test_all_packages' 🚖
🚀 Running tests for specified packages: CoreLayer/APIModels
▶️ Testing APIModels...
▸ Test Succeeded
✅ APIModels: 1/1 tests passed
Coverage: ⚠️ No coverage data
📊 Test Results Summary
✅ Passed: 1 packages, 1 tests
• APIModels - 1/1 tests
Coverage: ⚠️ No coverage data
📈 Overall Statistics
Total tests: 1
Passed: 1
Failed: 0
🎉 All tests passed successfully!
Cruising back to lane 'ios test_changed_packages' 🚘
fastlane.tools finished successfully 🎉
With this new test_changed_packages lane, we can now speed up development, run the tests more often, and save valuable CI time.