Sourcemap support for preprocessors?

[kulshekhar]

When used with typescript, the output displays line numbers from transpiled javascript and not from the actual typescript code.

I've modified this sample typescript preprocessor to set sourceMap, inlineSourceMap and inlineSources to true in typescript's options but it didn't help.

Is there anything else that I can do to get jest to display the mapped line numbers?

[cpojer]

Can you try to modify the sample preprocessor again and run Jest with --no-cache while working on the preprocessor?

Unfortunately we don't currently have an official typescript preprocessor (besides the example). If you'd like to work on this and send a pull request for adding typescript-jest, that would be awesome!

I'm closing this for now because we can't really do much if it isn't part of Jest.

[kulshekhar]

I tried this with --no-cache but it didn't work.

I tested the sample preprocessor and it seems to be working well with the added flags. The transpiled code contains the sourcemap inline.

This leads me to assume that whatever work needs to be done to display the correct (mapped) line numbers will probably need to be done in the Jest code that uses the preprocessor.

Is this assumption right? If so, can you point to the part of the codebase (a quick, rough indication would be helpful too) that I can look at to see if I can submit a usable PR?

[cpojer]

Are inline sourcemaps supposed to work automatically when using node and when using the vm module? Because Jest uses vm to run tests.

All of this code is in packages/jest-runtime – transform.js creates vm.Script instances.

If you are willing to help out, please join our discord channel (see https://facebook.github.io/jest/support.html ) – I'm usually there and happy to help. Creating typescript-jest would be awesome and should be fairly straightforward.

[kulshekhar]

Upon looking into this, I've discovered that node doesn't have any native support for sourcemaps. Without sourcemap support, creating typescript-jest would most likely be meaningless.

I've been trying to see if I can get https://github.com/evanw/node-source-map-support to work with the typescript preprocessor. If I can, I'll create typescript-jest using it and send a PR.

[cpojer]

Can typescript somehow retain lines, just like babel can?

[kulshekhar]

There's no such option in the typescript compiler

[cpojer]

ah that sucks :(

[kulshekhar]

Just in case there's someone else with this problem, I've created a repo with information about the setup that's working for me - https://github.com/kulshekhar/typescript-jest

Edit: the repo is at https://github.com/kulshekhar/ts-jest and the npm package is ts-jest

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