With cached results, changes to type definitions are not detected between packages

[drrnkin]

🐛 Bug Report

When a typescript package is compiled with type info, changes to the type info may be missed by ts-jest when the package is referenced from another package. Similar to #1747 but not identical.

To Reproduce

Steps to reproduce the behavior:
Unzip the attached zip file and follow the README.txt, which is copied inline here:

In the examplePackage folder, run:
yarn
yarn build
yarn link

In the consumerWithTest folder, run:
yarn
yarn link @example/package
yarn test

So far so good (the jestCache folder is created).
Now edit index.ts to uncomment b: number; and in the examplePackage folder, run:
yarn build

In the consumerWithTest folder, run:
yarn test

This should fail due to the change in type definition in index.ts, but passes.
Running yarn test --no-cache correctly identifies the problem.

jestCacheIssue.zip

Expected behavior

Type info should be respected without clearing the cache

Link to repo (highly encouraged)

Debug log:

# content of ts-jest.log :

envinfo

System:
    OS: Windows 10
    Node version: v14.16.1

Npm packages:
    jest: (included in zip) 27.0.6
    ts-jest: (included in zip) 27.0.3
    typescript: (included in zip) 4.3.4

[drrnkin]

Hi @ahnpnl. Other than the mention in #2696, I haven't seen any official acknowledgement of this bug. The other bug mentioned a design choice. Does that mean a significant redesign is in the works?

[ahnpnl]

I would say yes, it’s quite a change, generally speaking is: moving type check to one phase earlier in transform process.

The current design is: collecting all dependencies to construct cache keys and let Jest handle when a file needs to be rechecked.

What I have in mind for a design change is: instead of letting Jest handle, we would always do type check before creating a Jest cache key (ofc only do this when user uses cache). Following this approach will technically solve issues but probably require a smart way of caching for ts-jest so that we only do type check for files which have been changed or when its dependencies have been changed.

[drrnkin]

Is there any ETA on when this bug might be fixed? Our team keeps experiencing it and it's quite costly for us.

[drrnkin]

For the record, I ended up working around this. I changed our build scripts to compile our test code with the TS compiler, not just the product code. We still use ts-jest to run the tests but the cache bug won't affect us because compilation errors are caught by the TS compiler.