Matching against transitive dependencies (enhance `reachable` rules)

[billiegoose]

Context

I am trying to figure out where my application is importing a very heavy npm module that should only imported by code that is behind a dynamic import and React.lazy, but for some reason it's getting bundled into the main index.js bundle.

Now eventually I'll find it, but I'd love to declare a rule to prevent this from happening again. I can catch if it is directly imported:

{
      from: {
        path: '^app',
      },
      to: {
        path: '^node_modules/big-heavy-library',
        dynamic: false,
      }
}

and I can catch when it is loaded transitively:

{
      from: {
        path: '^app',
      },
      to: {
        path: '^node_modules/big-heavy-library',
        reachable: true,
      }
}

but I cannot use reachable: true in combination with dynamic: false or with other qualifiers. (And it's not clear how dynamic: false would be interpreted unless combined with a qualifier like "all modules in the via chain", "some modules in the via chain", "no modules in the via chain")

Expected Behavior

I'd like to be able to match against the via modules, like:

{
      comment: "big-heavy-library must be behind a dynamic import",
      from: {
        path: '^app,
      },
      // none of the links in the chain are dynamic imports
      viaNot: {
        dynamic: true
      },
      to: {
        path: '^node_modules/big-heavy-library',
        reachable: true,
      }
}

Current Behavior

I can either catch transitive imports or static imports, but not static transitive imports.

Possible Solution

Considered alternatives

Make all transitive imports forbidden and use ignore-known... but first I gotta catch the one that's already in my app.

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.

[oehme]

Do you still plan on adding this? I see you added the necessary backend, but it never made its way into the rule.

This would be super useful to verify architecture constraints like "things in layer A should not transitively reference things in layer B, except through this narrow API`.

[sverweij]

Hi @oehme, thanks for the heads-up! I had totally missed getting around to that indeed. I've started the implementation (step by step - as you can see in the draft PR).