Support TypeScript 4.x

[known-as-bmf]

🚀 Feature Proposal

TypeScript 4.0.2 has just been released and ts-jest now outputs a warning:

ts-jest[versions] (WARN) Version 4.0.2 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.

I know it says that I should not report an issue but this warning is outputted to stderr and can break some CIs that consider anything outputted to stderr a failure.

I also know that you can disable this warning via an environment variable, but it is not ideal/recommended.

As long as the environment variable TS_JEST_DISABLE_VER_CHECKER stays, the warning message will no longer show. This can lead to unexpected errors due to the usage of incompatible versions’ dependencies. Use this environment variable with precautions.

It doesnt seem like this new version has hard breaking changes, so it should be supported out of the box.

Motivation

No more warning messages that could break some CIs.

Example

N/A

[erfanium]

When will this be released? I'm waiting

[ahnpnl]

Hi, somewhere next week will be :)