MCQs on Dependency Injection and Inversion of Control | C#
Dependency Injection (DI) and Inversion of Control (IoC) are vital concepts in modern C# development. They help improve code maintainability, testability, and flexibility. Below are 30 multiple-choice questions (MCQs) on these topics, divided into relevant sections. These questions cover DI fundamentals, IoC containers like Unity and Autofac, different injection methods, and the benefits of DI in C# development.
1. Introduction to Dependency Injection (DI)
- What is Dependency Injection in C#?
- A) A design pattern
- B) A language feature
- C) A framework
- D) A library
- What is the main purpose of Dependency Injection?
- A) To improve code readability
- B) To decouple objects
- C) To increase memory usage
- D) To speed up program execution
- Which of the following is a common method of Dependency Injection?
- A) Interface Injection
- B) Constructor Injection
- C) Reflection Injection
- D) Event Injection
- What problem does Dependency Injection solve in software development?
- A) Tight coupling between classes
- B) Memory leaks
- C) High CPU usage
- D) Low performance
- Which of the following is NOT a feature of Dependency Injection?
- A) Improves testing
- B) Increases flexibility
- C) Decreases code complexity
- D) Reduces code coupling
- Which of the following is an example of a Dependency Injection container in C#?
- A) .NET Core DI
- B) Ninject
- C) Castle Windsor
- D) All of the above
- What is the benefit of Dependency Injection in unit testing?
- A) Simplifies the code
- B) Allows mocking of dependencies
- C) Increases CPU usage
- D) Reduces the need for code refactoring
- Which of the following is a characteristic of the Inversion of Control (IoC) principle?
- A) Control over the flow of the program is transferred to a container
- B) All classes are tightly coupled
- C) Dependencies are created manually
- D) Classes handle their dependencies directly
- What does Dependency Injection eliminate in terms of class dependencies?
- A) Direct dependency on external libraries
- B) Need for constructors
- C) Need for manual dependency management
- D) Both A and B
- What type of dependency does DI primarily address?
- A) System-level dependencies
- B) Internal class dependencies
- C) Third-party API dependencies
- D) Database dependencies
2. IoC Containers (Unity, Autofac)
- Which of the following is a popular Dependency Injection container in C#?
- A) Unity
- B) Ninject
- C) Autofac
- D) All of the above
- What is Unity in the context of Dependency Injection?
- A) A programming language
- B) A Dependency Injection container
- C) A code generator
- D) A testing framework
- What does Autofac primarily provide?
- A) A high-performance DI container
- B) A data storage solution
- C) A web development framework
- D) A code analysis tool
- Which of the following is true about Unity container in C#?
- A) It allows object creation and dependency management
- B) It is used only for object serialization
- C) It is slower than all other DI containers
- D) It only works with web applications
- How does Autofac improve performance in a DI system?
- A) By using reflection to speed up initialization
- B) By reducing object creation at runtime
- C) By caching instances for reuse
- D) All of the above
- Which of the following containers supports both Constructor and Property injection?
- A) Unity
- B) Autofac
- C) Both Unity and Autofac
- D) None of the above
- Which feature is common between Unity and Autofac containers?
- A) They support registering components by interface
- B) They do not support constructor injection
- C) They are both open-source
- D) They are both web-only containers
- What is a key advantage of using an IoC container like Unity or Autofac?
- A) Automatically handling all memory management
- B) Managing and resolving object dependencies
- C) Making the code more complex
- D) It replaces all object constructors
- How are components registered in Autofac?
- A) By using attributes
- B) By using a configuration file
- C) By calling container methods at runtime
- D) Through reflection
- Which IoC container is considered highly extensible and modular in C#?
- A) Ninject
- B) Unity
- C) Autofac
- D) Castle Windsor
3. Constructor Injection, Property Injection, and Method Injection
- What is Constructor Injection in Dependency Injection?
- A) Passing dependencies via class properties
- B) Passing dependencies through method parameters
- C) Passing dependencies through the class constructor
- D) Using interfaces to define dependencies
- Which of the following is a key feature of Property Injection?
- A) Dependencies are passed through constructors
- B) Dependencies are passed through public properties
- C) Dependencies are passed via method arguments
- D) It does not require a DI container
- What is the primary use case for Method Injection?
- A) When dependencies need to be injected at runtime
- B) When dependencies are static
- C) When dependencies are constant throughout the application
- D) When dependencies are injected via constructors
- Which type of injection allows dependencies to be set after object creation?
- A) Constructor Injection
- B) Method Injection
- C) Property Injection
- D) None of the above
- What is the main advantage of Constructor Injection?
- A) Dependencies are optional
- B) Ensures that all dependencies are available when the object is created
- C) More flexible than Property Injection
- D) Can be used without an IoC container
- In which scenario is Property Injection generally used?
- A) When all dependencies are required immediately
- B) When dependencies can be set later in the object’s lifecycle
- C) For singleton objects
- D) For performance optimization
- Which of the following is true about Method Injection?
- A) It is the most common type of dependency injection
- B) It is only useful for short-lived objects
- C) Dependencies are passed through methods rather than constructors or properties
- D) It is the least flexible type of injection
- Which type of injection is best for objects with many dependencies?
- A) Constructor Injection
- B) Property Injection
- C) Method Injection
- D) None of the above
- What type of injection is generally recommended for immutability and ensuring dependencies are provided at object creation?
- A) Constructor Injection
- B) Property Injection
- C) Method Injection
- D) Interface Injection
- Which of the following is a disadvantage of Property Injection?
- A) It can lead to incomplete object states if dependencies are not set
- B) It requires complex code refactoring
- C) It is slower than Constructor Injection
- D) It reduces code readability
Answers
| Qno | Answer |
|---|---|
| 1 | A) A design pattern |
| 2 | B) To decouple objects |
| 3 | B) Constructor Injection |
| 4 | A) Tight coupling between classes |
| 5 | C) Decreases code complexity |
| 6 | D) All of the above |
| 7 | B) Allows mocking of dependencies |
| 8 | A) Control over the flow of the program is transferred to a container |
| 9 | D) Both A and B |
| 10 | B) Internal class dependencies |
| 11 | D) All of the above |
| 12 | B) A Dependency Injection container |
| 13 | A) A high-performance DI container |
| 14 | A) It allows object creation and dependency management |
| 15 | D) All of the above |
| 16 | C) Both Unity and Autofac |
| 17 | A) They support registering components by interface |
| 18 | B) Managing and resolving object dependencies |
| 19 | C) By calling container methods at runtime |
| 20 | C) Autofac |
| 21 | C) Passing dependencies through the class constructor |
| 22 | B) Dependencies are passed through public properties |
| 23 | A) When dependencies need to be injected at runtime |
| 24 | C) Property Injection |
| 25 | B) Ensures that all dependencies are available when the object is created |
| 26 | B) When dependencies can be set later in the object’s lifecycle |
| 27 | C) Dependencies are passed through methods rather than constructors or properties |
| 28 | A) Constructor Injection |
| 29 | A) Constructor Injection |
| 30 | A) It can lead to incomplete object states if dependencies are not set |