eslint-plugin-explicit-inject

ESLint rule that enforces explicit @Inject() on constructor parameters of DI-decorated classes.

Setup

pnpm add -D eslint-plugin-explicit-inject

In your eslint.config.js:

import explicitInjectPlugin from "eslint-plugin-explicit-inject";

export default [
  explicitInjectPlugin.configs.recommended,
  // ...your other configs
];

What it catches

// Bad - will be flagged
@Injectable()
class MyService {
  constructor(private fooService: FooService) {}
}

// Good
@Injectable()
class MyService {
  constructor(@Inject(FooService) private fooService: FooService) {}
}

Any decorator on a parameter counts as explicit (not just @Inject), so @Optional(), @Inject(), custom decorators all pass.

By default, only @Injectable() classes are checked.

Configuration

The rule accepts a decorators option to specify which class decorators trigger the check. This is useful for NestJS projects where @Controller(), @Resolver(), and other decorators also use constructor injection:

import explicitInjectPlugin from "eslint-plugin-explicit-inject";

export default [
  {
    ...explicitInjectPlugin.configs.recommended,
    rules: {
      "explicit-inject/require-inject-decorator": ["error", {
        decorators: ["Injectable", "Controller", "Resolver"]
      }]
    }
  }
];

When no decorators option is provided, it defaults to ["Injectable"].

Local development

pnpm install
pnpm test
pnpm build

To try the built plugin in another project before publishing, add to that project's package.json:

{
  "devDependencies": {
    "eslint-plugin-explicit-inject": "file:/path/to/this/repo"
  }
}

Then pnpm install in that project. After making changes here, run pnpm build, then pnpm install again in the target project.

Requirements

• ESLint 10+
• @typescript-eslint/parser 8+