Typings nightmare with @types/xxx

[tomitrescak]

This is not a bug, rather call for help.
Since recently packages started to install dependencies from @types repo.

From this moment on none of my projects is compilable as I am using Mocha for my tests, yet one of the packages uses Jest. Both of these packages declare "describe. it ..." in the global space.

So, I have @types/jest and @types/mocha installed in the node_modules folder.

As a result, no project will compile and my CI is out of order.

The only possibility that comes to my mind is to roll back to "classic" module resolution and copy the definitions into my project manually.

Is this true? Is there anything else I can do?

[EDIT]

I put moduleResolution to "classic" and it is still compiling stuff in the @types folder!!! WHY?

[yortus]

I am using Mocha for my tests, yet one of the packages uses Jest

Shouldn't that package have @types/jest as a devDependency rather than as a dependency? Then @types/jest won't be installed when you npm install your own module.

Generally the packages you depend on should not bring in their development dependencies (built/test infrastucture), just their executable code. But I can't really tell if this is the situation from the description above.

[tomitrescak]

Well, I am not that package developer and this is what happens. Installing that package "Jest" appears in my typings folder.

[yortus]

Can I ask what the package is? If it is a deps vs devDeps issue in their package, then the fix is simple for them to make and the problem will go away for you.

[tomitrescak]

Hi, I already created an issue with this. But I guess, the problem is not so isolated. Is there any other mean of protection from this apart from waiting for package developer to update and release a new version? Thanks.

[yortus]

Hopefully someone else can answer if there's a workaround for this.

In the mean time it would be helpful if the team promoted the proper use of devDependencies with @types typings. In recent blog posts (e.g. here and here) they show installing @types as normal dependencies, which means all clients of such packages will also needlessly get those types installed, even though they are not needed to run the package code.

At best it's a useless dependency for clients, but sometimes it may lead to clashes/errors such as the one you've reported here.

[weswigham]

If you want a complex workaround, you should be able to manually remove the unwanted folder from your transitive @types by running npm shrinkwrap to pickle your dependencies, then edit the generated npm-shrinkwrap.json to remove the @types package you do not want to include. Then just delete it from disk and the shrinkwrap should prevent it from being installed for anyone else.

It's a bit of a kludge, but it can workaround packaging dependency conflicts like this.

[tomitrescak]

I was really hoping that skipDefaultLibCheck will do good here as it its said to skip validation of .d.ts files, but it seems to do nothing as .d.ts files are still validated :/

[mhegazy]

@tomitrescak, just to make sure i understand, there are two projects, one depend on mocha, while the other use Jest? or is it that you have projects that depend on both?

if it is the earlier, then the fix is to use "types" : ["mocha"] in your tsconfig.json; this will instruct the compiler to only load @types/mocha in this project, then for the other project "types" : ["jest"] .

if it is the later. then what you need is to "break the tie" between the two declarations in some way. so options, consider creating a new folder: "overrides" , and add "overrides\jest\index.d.ts" to be what you thinkjestshould be. then update your tsconfig.json to include"typeRoots": [".\overrides", ".\node_modules@types"]. What this does it tells the compiler to look for types first in".\overrides\jest"and if it did not find it to look in".\node_modules@types\jest"`.

Ultimately the fix is on the declaration file side, and i would recommend you send a PR to DT with a fix that removes the declaration of it, declare etc.. to a different package that both jest and mocha depend on.

See http://www.typescriptlang.org/docs/handbook/tsconfig-json.html#types-typeroots-and-types for more details on this.

[tomitrescak]

@mhegazy thanks for the explanation. That link really helped. My problem was the first one, where a project I'm depending on was installing "jest" into @types folder, while I am using mocha. They both depend on global variables which were clashing.

Would be great to point to that page in the list of the compiler options.

[mhegazy]

Added links to docs in microsoft/TypeScript-Handbook@a83f002

[tomitrescak]

Fantastic, thanks!