What are we testing?

Project has a support file that uses cypress-axe, which uses axe-core, both of which are installed by PnP and don't live in node_modules, but are preprocessed by cypress via webpack in ./packages/server/node_modules/@cypress/webpack-batteries-included-preprocessor (./npm/webpack-batteries-included-preprocessor packaged with Cypress server) relative to the monorepo root. That webpack binary needs to resolve its build dependencies from within the cypress binary, including built-ins to process, but needs to resolve the dependencies bundled in the specs/support file from the pnp cache.

Since dependencies cannot be installed normally as we do with regular system tests via yarn v1, we need to run this as a binary system test. See yarn-pnp-preprocessor-system-test inside ./circleci/workflows.yml.