Jest - Fastify v5 - [email protected] - error in tests from buildCache

[javierxbrenes1]

Hey, we have tried to update our BE app to start using Fastify v5, we had to update to [email protected], but now when we want to run our tests -we use jest- we are getting the following error:

  TypeError: A dynamic import callback was invoked without --experimental-vm-modules

      at buildCache (../node_modules/mercurius/index.js:65:20)
      at Object.<anonymous>.fp.name (../node_modules/mercurius/index.js:71:21)
      at Plugin.Object.<anonymous>.Plugin.exec (../node_modules/avvio/lib/plugin.js:125:28)
      at Boot.Object.<anonymous>.Boot._loadPlugin (../node_modules/avvio/boot.js:432:10)

Seems buildCache does something like const QuickLRU = (await import('quick-lru')).default we know Nodejs supports this, but seems that Jest doesn't like it.

is there any way to deal with this ?

[mcollina]

@voxpelli introduced the dependency on quick-lru in #1108. Maybe there is another LRU implementation that we can use that is not an ESM.

Anyhow, I recommend to not use jest, mostly for these kind of issues.

[voxpelli]

Yikes, Jest doesn’t support dynamic import of ESM modules?!

One can surely find or make an LRU implementation that behaves like a Map and isn’t an ESM module, but even if one does there is no guarantee that no other dependency of Mercurius suddenly starts using dynamic imports of ESM in their CJS – because that is perfectly fine and not a breaking change to do.

I would say that Jest is the one in the wrong here.

[voxpelli]

@javierxbrenes1 Have you tried running the tests with --experimental-vm-modules?