How to mock a constructor - Junit test case development issues
While writing JUnit test cases, we encounter cases like we want to initialize a…
January 12, 2022
In a Spring boot app, we tend to use @Autowire
annotation, so that Spring can inject our dependency. It helps in not writing the constructor explicitly and developer doesn’t need to take care of from where this bean is coming.
Example Code
@Autowired
private UserService userService;
At some point, we encounter errors like below:
***************************
APPLICATION FAILED TO START
***************************
Description:
Field <your-field> in com.your-package.controllers.MyController required a bean of type 'com.your-package.service.UserService' that could not be found.
The injection point has the following annotations:
- @org.springframework.beans.factory.annotation.Autowired(required=true)
Action:
Consider defining a bean of type 'com.your-package.service.UserService' in your configuration.
@Autowire
searches in the spring context for the bean.
There might be few probable reasons of this error:
You have not defined the bean anywhere (Unless you declared the class with annotations like service/component etc, see next point). If you are using xml spring context, define the bean there.
You forgot to declare the class with annotations like: @Component, @Service, @Controller, @Configuration, @Repository
, there might be more
(Note: above annotations are for respective purposes, so use them as per use-case)
new
), Autowire will not work there. As, that instance will not be registered to Spring for dependency injection.So, do not initialize a class by explicit constructor. Let spring handle it for you.
@ComponentScan
, but in wrong package. Specify the correct package there. You can specify multiple packages there as well.@ComponentScan({ "com.path1", "com.path2", "com.path3"})
Your spring-boot main class (@SpringBootApplication
), is located in some inner package. By default, spring boot main class, scans the child packages. So, if you have defined your main class in some inner package, move it to the top package.
There might be mutiple beans of same class. You need to help @Autowire
, that which bean name you want to take.
Use:
@Autowired
@Qualifier("userService")
private UserService userService;
@ComponentScan
in your main class @SpringBootApplication
@SpringBootApplication(scanBasePackages = { "com.path1", "com.path2"})
public class MyApplication {
public static void main(String[] args) throws InterruptedException {
SpringApplication.run(MyApplication.class, args);
}
}
OR
@SpringBootApplication
@ComponentScan({ "com.path1", "com.path2"})
public class MyApplication {
public static void main(String[] args) throws InterruptedException {
SpringApplication.run(MyApplication.class, args);
}
}
Hope it helps.
While writing JUnit test cases, we encounter cases like we want to initialize a…
Introduction On 9th December 2021, an industry-wide vulnerability was discovered…
Suppose you have two lists, and you want Union and Intersection of those two…
Introduction I was trying to integrate Okta with Spring, and when I deploy the…
I have a Java project and dependencies are being managed through maven. I have…
Its good to write unit tests cases, and this part is mostly forgotten by…
Introduction This post has the complete code to send email through smtp server…
Introduction In a normal email sending code from python, I’m getting following…
Introduction In one of my app, I was using to talk to . I have used some event…
Introduction So you have a Django project, and want to run it using docker image…
Introduction It is very important to introduce few process so that your code and…
Introduction In this post, we will see a sample Jenkin Pipeline Groovy script…