Jest moduleNameMapper and NPM package exports - node.js

Question

I am developing fullstack NPM packages with multiple entrypoints (namely client, server and sometimes tests), using the exports property of package.json.
I also use a small hack to make TS work with exports until it's officially supported (see this Stack Overflow post, this hackish solution and this ticket).
The package.json ends up looking like this:
{
"name": "#vulcanjs/graphql",
"version": "0.4.7",
"main": "./dist/index.js",
"files": [
"dist/"
],
"exports": {
".": "./dist/index.js",
"./server": "./dist/server/index.js",
"./testing": "./dist/testing.js"
},
"types": "./dist/index.d.ts",
"typesVersions": {
"*": {
"server": [
"./dist/server/index.d.ts"
],
"testing": [
"./dist/testing.d.ts"
]
}
},
"description": "Vulcan graphQL schema generator",
...
You can then import using either #vulcanjs/graphql for shared code, and #vulcanjs/graphql/server for Node.js-only code.
It works perfect in my Next.js app. However, it seems to break Jest moduleNameMapper.
First, I had this:
moduleNameMapper: {
"#vulcanjs/(.*)": [
"<rootDir>/node_modules/#vulcanjs/$1",
],
},
The error is:
Configuration error:
Could not locate module #vulcanjs/graphql/server mapped as:
[
"/code/vulcan-next/node_modules/#vulcanjs/graphql/server",
].
The problem is that it tries to find a package named #vulcanjs/graphql/server: yet "server" is not a different package, it's an entrypoint of #vulcanjs/graphql.
I've also tried this:
moduleNameMapper: {
"#vulcanjs/(.*)/(.*)": [
"<rootDir>/node_modules/#vulcanjs/$1",
],
},
With this config, #vulcanjs/graphql/server is mapped to #vulcanjs/graphql. The problem is that now, server code is not found. I've checked and the problem is that this solution totally removes the /server: so #vulcanjs/graphql/server points to the main entrypoints instead of the server entrypoint.
Finally I did try to remove the moduleNameMapper, but then #vulcanjs/graphql/server package is not found by Jest. Note that I need the mapper for a use case I did not demonstrate here, so getting rid of it is possible but not the best solution.
The bug can be reproduced by installing the framework: https://github.com/VulcanJS/vulcan-next. You can clone, yarn install, unskip the test in src/models/tests/sampleModel.server.test.ts and run yarn run test:unit sampleModel. It will show the error.
Any idea how I could fix this?