Concrete Dependency Injection (ARCH3199)

Key typescript.quality.concrete-dependency · Severity info · Category quality

Typing constructor dependencies as concrete classes violates the Dependency Inversion Principle (DIP); it couples the component to a specific implementation and makes mocking for tests harder.

Incorrect

class ReportService {
  constructor(private repo: SqlOrderRepository) {}
}

Correct

interface OrderRepository {
  findAll(): Promise<Order[]>;
}

class ReportService {
  constructor(private repo: OrderRepository) {}
}

Fix

Type dependencies against interfaces or abstractions instead of concrete classes.