split-tests

Github Action for splitting a test suite into equal time groups for parallel execution.

Introduction

This actions allows you to split up a suite of tests so they can be executed in parallel across a fleet of runners. The overall goal is to reduce developer feedback time by distributing the load.

Usage

Splitting Methods

File Count (Default)

This is a naive split into an even number of files per group. It is the default splitting method.

Line Count

Another naive split, but this time based on the number of lines per test. It is used by setting line-count: true

JUnit Report

This is the most intelligent split mechanism, using previous execution durations for each test from the JUnit report. It is used by setting the junit-path to the location of a previous execution's JUnit results report in your repository

Inputs

NAME	DESCRIPTION	TYPE	REQUIRED	DEFAULT
split-index	Index of this instance executing the tests	integer	✅
split-total	Total number of instances executing the tests	integer	✅
glob	Glob pattern to find test files (default "spec/**/*_spec.rb")	string		spec/**/*_spec.rb
exclude-glob	Glob pattern to exclude test files	string		""
junit-path	Path to a JUnit XML report to use for test timings	string		""
line-count	Use line count to estimate test duration	bool		false

Outputs

NAME	DESCRIPTION	TYPE
test-suite	A subset of tests, based on the the split index and split type	string
split-index	Index of this instance executing the tests	number
split-total	Total number of instances executing the tests	number

Example Workflow

env:
  total-runners: 5

jobs:
  runner-indexes:
    runs-on: ubuntu-latest
    name: Generate runner indexes
    outputs:
      json: ${{ steps.generate-index-list.outputs.json }}
    steps:
      - id: generate-index-list
        run: |
          MAX_INDEX=$((${{ env.total-runners }}-1))
          INDEX_LIST=$(seq 0 ${MAX_INDEX})
          INDEX_JSON=$(jq --null-input --compact-output '. |= [inputs]' <<< ${INDEX_LIST})
          echo "::set-output name=json::${INDEX_JSON}"

  run-parallel-tests:
    runs-on: ubuntu-latest
    name: "Runner #${{ matrix.runner-index }}: Run test suite in parallel"
    needs:
      - runner-indexes
    strategy:
      matrix:
        runner-index: ${{ fromjson(needs.runner-indexes.outputs.json) }}
    steps:
      - uses: actions/checkout@v2
      - uses: chaosaffe/split-tests@v1-alpha.1
        id: split-tests
        name: Split tests
        with:
          glob: examples/spec/**/*_spec.rb
          split-total: ${{ env.total-runners }}
          split-index: ${{ matrix.runner-index }}
      - run: 'echo "This runner will execute the following tests: ${{ steps.split-tests.outputs.test-suite }}"'

The complete workflow can be found at .github/workflows/example.yaml

Dependencies

This action uses leonid-shevtsov/split_tests under-the-hood to accomplish the test splitting