fix: #825 handle symlinked modules (ala pnpm) correctly

[aquark]

I was having problems with ts-jest failing to compile in my pnpm monorepo with weird errors because it apparently wasn't finding dependencies of @types packages, despite the fact that tsc works fine. This change fixes it.

The reason is that pnpm symlinks packages like this:

> ls -l node_modules/@types/
express -> ../../../../node_modules/.registry/@types/express/4.17.0/node_modules/@types/express

The transitive dependencies are not in the consuming package's node_modules or its parents, instead they are in ../../../node_modules/.registry/@types/express/4.17.0/node_modules/, so it's necessary to resolve the symlink to its referent in order to find the dependencies. When ts-jest doesn't implement this resolution, TypeScript assumes all the files are not symlinks and doesn't find the dependencies. Depending on how dependencies are structured this results in missing type information which causes strict type checking to fail.

[coveralls]

Pull Request Test Coverage Report for Build 2888

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 91.601%

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Totals
Change from base Build 2864:	0.0%
Covered Lines:	915
Relevant Lines:	967

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💛 - Coveralls

[kulshekhar]

@aquark thank you very much for the PR!

[bruk1977]

@kulshekhar I need this fix very badly... do you have any idea when this fix could be released? Looks like that last release is last April :(

[bruk1977]

@aquark are you using this fix? do you publish it by a different name? Looks like the latest release don't have this fix.

[aquark]

Yes, I'm using it with a private npm registry

[bruk1977]

Thanks @aquark for the quick reply. When I'm trying to publish to a private npm registry, I'm getting the following errors... any idea how to get around them?

ts-jest/e2e/helpers/source-maps.ts:1:50
ERROR: 1:50 prettier Delete ␍

ts-jest/e2e/helpers/templates.ts:1:26
ERROR: 1:26 prettier Delete ␍
ERROR: 2:23 prettier Delete ␍
ERROR: 3:27 prettier Delete ␍
ERROR: 4:41 prettier Delete ␍
ERROR: 5:13 prettier Delete ␍
ERROR: 6:51 prettier Delete ␍
ERROR: 7:2 prettier Delete ␍
ERROR: 8:104 prettier Delete ␍
ERROR: 9:109 prettier Delete ␍