How to debug CI errors ?

[asvny]

For context: I am trying to switch package manager from yarn 1.x to pnpm 8.x in my workplace. As a first step, I used pnpm import yarn.lock to generate the pnpm lockfile and after with some I was able to get most of it working(build source, storybook, linting, E2E etc..,) except jest unit tests.

Currently in my local env, when I run pnpm test (i.e, "test": "jest") most of the tests pass, except few. But it is not the same case in CI, all tests fail due to some package

Local env

CI env

My questions are ...

• what makes both environments different ?
• How can I reproduce the same CI error?
• How can I keep environments deterministic in future ?