Examples comparing ts-jest and Jest setups

[tkrotoff]

Following this discussion

The Jest example works with vscode debugger
The ts-jest example does not work with vscode debugger - I don't know how to make it work in an elegant way

[kulshekhar]

@tkrotoff thanks!

[kulshekhar]

The Jest example works with vscode
The ts-jest example does not work with vscode - I don't know how it to make it work

I tested the examples from the command line and they worked there. I think adding these in despite the issue with vscode would be better than not adding them.

[tkrotoff]

Well, before merging this, I wanted you to review it and discuss it with you and see how to make ts-jest work with vscode debugger.

If you check carefully the examples, I don't see any benefit for using ts-jest over Jest directly (with a tsc pre-task).

I though ts-jest would allow me to remove the tsc pre-task but then vscode debugger won't work.

Overall, I don't understand what problem ts-jest is trying to solve and the readme does not help on this.

Edit, clarification:
I consider that setting breakpoints and debugging my tests written in TypeScript is a must have feature.
I don't see how people could develop something bigger than an "hello world" without this feature.
Why examples with vscode debugger? it is the most popular editor (from what I've seen) when writing in TypeScript.

[kulshekhar]

@tkrotoff ok. I misunderstood what you were trying to say.

The reason I created ts-jest was solely because I wanted sourcemap support for tests written in typescript. The only way to see this issue is by introducing a bug in a typescript file in a part that is covered by a test. Without ts-jest, at least when I had tried, the tests failed with line numbers based on the transpiled javascript file and not the original typescript files.

Does this bring some clarity?

As for vscode, even though that is what I use, integration with it wasn't a priority for me. Neither was coverage, for that matter.

Should I now revert this merge?

[kulshekhar]

Looking at this again, merging was probably hastily done. I'll revert this now and look at this again later

[tkrotoff]

Without ts-jest [...] the tests failed with line numbers based on the transpiled javascript file and not the original typescript files

I see, that matches the README.md line: be able to locate errors.

As for vscode [...] integration with it wasn't a priority for me.

Approaches to solve the problem:

• Tell vscode where the generated .js (+ source map) files are thx to cacheDirectory - in practice this does not work
  ts-jest could write down in a special directory known to vscode the generated *.js files

• ts-jest does not generate the .js files: a pre-task does the job instead and ts-jest just returns the previously generated .js files to Jest for the line numbers to be OK

Edit:
This is not specific to vscode. Jest cannot be debugged when using a source map preprocessor => any debugger need to have access to the generated *.js files.