Support monorepo

Issue :

At the moment, ts-jest doesn’t support well monorepo (typescript composite, yarn workspace, lerna etc…). This issue contains all related issues to monorepo:

#1341 : Cannot use rootMode upward for babel config (fixed via #1370) #1336 : Error Unable to require d.ts for yarn workspace and typescript composite. (fixed via #1385) #1333: Use wrong version of typescript in yarn workspace (fixed via #1377) #1277 : Cannot collect coverage with custom compiler e.g ttypescript for lerna workspace. #1134 : Compatibility with yarn workspaces pnp #1109 : Cannot import mixin in yarn workspace and typescript compsite

Expected behavior :

Support monorepo out of the box or at least for common ones like yarn workspace, typescript composite, lerna.

Minimal repo :

Example repos are in those above issues

Problem

At the moment ts-jest is lack of helps. We would need community’s help in tackling this issue. Feel free to contribute PRs if you have good ideas related to this issue.

cc @kulshekhar

[ahnpnl]

@quadgod coverage collection isn’t taken care by ts-jest. We would solve only the 2nd issue which is about TypeScript

[octogonz]

Heft is an interesting alternative for integrating Jest+TypeScript in a monorepo scenario.