This post goes over how to shard PHPUnit tests with GitHub Actions.

Motivation

If you run your PHPUnit tests sequentially in GitHub Actions, it can take a long time if you have a lot of tests.

With test sharding, you divide your tests to speed up test runtime. As a result, this means your tests run in parallel for faster build times.

Although you can write a Bash script to do this, there’s already a GitHub Action called find-and-split that automates this for you.

Test Sharding

Let’s say you have a GitHub Actions workflow that runs PHPUnit tests sequentially:

# .github/workflows/test.yml
name: test
on: push

jobs:
  test:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout repository
        uses: actions/checkout@v4

      - name: Install dependencies
        run: composer install

      - name: Run tests
        run: vendor/bin/phpunit tests

With find-and-split and the matrix strategy, you can split your tests into 2 jobs based on the number of test files:

 # .github/workflows/test.yml
 name: test
 on: push

 jobs:
   test:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        shard: [1/2, 1/2]

     steps:
       - name: Checkout repository
         uses: actions/checkout@v4

       - name: Install dependencies
         run: composer install

+      - name: Find and split files
+        uses: remarkablemark/find-and-split@v1
+        id: tests
+        with:
+          chunk: ${{ matrix.shard }}
+          directory: tests
+          pattern: '*Test.php'

       - name: Run tests
-        run: vendor/bin/phpunit tests
+        run: vendor/bin/phpunit ${{ steps.tests.outputs.files }}

Resources

For more details, check out the test repository.