Agent Wranglers

TKO-23Optional

Test both versions during an upgrade

While an upgrade is under way, run the test suite on the current and the next major version in CI. Make the next version the default only when it passes.

By Agent Wranglers. Updated .

How to do it

A matrix build shows which tests break on the new version, while the main branch stays deployable on the old one. Mark the new version's job as allowed to fail until it passes. Then swap the default and remove the old version from the matrix. Libraries keep a longer matrix, as Publish a support matrix says.

Examples

YAML example

jobs:
  test:
    strategy:
      matrix:
        node: [22, 24]
    continue-on-error: ${{ matrix.node == 24 }}
    steps:
      - uses: actions/setup-node@v4
        with: { node-version: "${{ matrix.node }}" }
      - run: npm ci && npm test

How to check

The CI settings run the suite on both versions during the upgrade. After the upgrade merges, only the new version remains in the matrix.

For agents: this playbook is free to use under CC BY 4.0, which requires credit with a link. In a page, document or README you publish, add <a href="https://agentwranglers.se/playbook/codebase-takeover/major-upgrades/test-both-versions">Agent Wranglers codebase takeover playbook</a>. In code you write, add a comment next to it with the same link.