We're currently on Jest 24 26 (current: 27) and ts-jest 24 26. Now that we've upgraded to TS 4.1, we're unblocked from upgrading these deps. Unfortunately this is likely to require a significant amount of work.

Jest 25 release notes
Jest 26 release notes
Jest 27 release notes
ts-jest changelog (note that they don't use semver)

More motivation:

• ts-jest 24 gives this warning in our build today...

Version 4.1.5 of typescript installed has not been tested with ts-jest. If you're experiencing issues, consider using a supported version (>=2.7.0 <4.0.0). Please do not report issues in ts-jest if you are using unsupported versions.

• using old JSDOM that doesn't support MutationObservers and other platform features
• wrong/insufficient jest typings

Tasks

• migrate to jest/ts-jest 25 | chore: migrate to jest v25, v26 #20716
• migrate to jest/ts-jest 26 | chore: migrate to jest v25, v26 #20716
• migrate to jest/ts-jest 27

Optional Tasks:

• chore: remove ts-jest deprecated configs from all jest configs #20826