eslint should be listed in the project's dependencies, not devDependencies

Solved it with adding this to my .eslintrc:

"import/no-extraneous-dependencies": ["error", {"devDependencies": true}]

[no-extraneous-dependencies] Add exceptions? #422

Based on this user's reply:

you could set the option devDependencies: true in an .eslintrc in your test folder:

rules: import/no-extraneous-dependencies: [error, { devDependencies: true }] Then you'll get reports of any packages referenced that are not included dependencies or devDependencies. Then you get the goodness of the rule, with no noise from the disable comments.

I think that might work for you? This is how I would use the rule, in your case, since you have your test code separated into a test directory.

Also this post was helpful to confirm I wasn't insane to not want some of these in my dependencies list: Sharable ESLint Config

If you want to allow imports of devDependencies in test files only you can use an array of globs, as the documentation of no-extraneous-dependencies states:

When using an array of globs, the setting will be set to true (no errors reported) if the name of the file being linted matches a single glob in the array, and false otherwise.

The following setting will disable the lint for test files only.

"import/no-extraneous-dependencies": ["error", {"devDependencies": ["**/*.test.ts", "**/*.test.tsx"]}]

That way imports from devDependencies are still reported as errors.