Module not found: Error: Can't resolve 'module' in 'node_modules/testdouble/lib'

[patrick99e99]

I have an angular app, and testdouble in my devDependencies of my package file. When I try to run my angular test suite, I am getting:

./node_modules/testdouble/lib/can-register-loader.js:1:15-32 - Error: Module not found: Error: Can't resolve 'module' in '/path/to/project/node_modules/testdouble/lib'

literally require('module'); is breaking...

I am wondering why this isn't an internal dependency of testdouble?

[Michael-Ziluck]

Please fix this!

[rosston]

I don't have any solutions here. But I might be able to point in the right direction. I assume you're running your tests in the browser via Karma? And that you're trying to use td.replaceEsm?

require('module') is breaking because it's trying to require the built-in Node.js module, probably because you're in a browser environment. From the replaceEsm docs, I think it pretty much relies on running within Node.js.

It'd be pretty easy to resolve that issue within can-register-loader.js by wrapping in a try/catch. But then you'll have other issues, since it looks like quibble (what testdouble.js uses for module mocking) also depends on core Node.js modules.

The short answer is that you'll probably be happier if you don't try to use replaceEsm in the browser. And probably only use replace to replace properties, not modules.