* reapply "switch from jest to vitest for faster, simpler tests (https://github.com/sourcegraph/sourcegraph/pull/57886)"
This was reverted in https://github.com/sourcegraph/sourcegraph/pull/58116 due to an issue with the browser tests.
* include fetch-mock
* fix flakiness
* rm mock that did not work in experimentalVmThreads
* fix
* timeout
* fixup
---------
Co-authored-by: William Bezuidenhout <william.bezuidenhout@sourcegraph.com>
When running vitests concurrently the target //client/browser:test fails
Revert "switch from jest to vitest for faster, simpler tests (#57886)"
This reverts commit ae5325e432.
Replaces our usage of jest with vitest. Also removes the babel transpiler. This simplifies our test configuration by a lot, makes tests run 10% faster, and makes further modernizations to our build/test stuff possible (such as using vite for frontend builds).
This removes some of the junit exporting for Buildkite, and the vitest bazel defs don't really cleanly implement bazel testing guidelines (like sharding). But vitest is only used for unit tests (all integration/e2e/regression tests have always run in mocha), so none of them are very slow anyway.
## Codemods for vitest imports
fastmod -e js,ts,tsx @jest/globals vitest client/ dev/release/
fastmod -e js,ts,tsx 'jest\.(\w+)\(' 'vi.$1(' client/ dev/release/
fastmod -e js,ts,tsx 'jest,' 'vi,' client/ dev/release/
fastmod -e js,ts,tsx 'jest }' 'vi }' client/ dev/release/
git diff --diff-filter=M --name-only | xargs pnpm exec prettier --write
