================
What is Junit ?
=================

=> Free & open source java based framework

=> It is used for unit testing

Note: It is used only for java projects unit testing

========================
What is Unit Testing ?
========================

=> Testing individual components of the application is called as Unit testing.

```
class UserService {
	
	m1() {
	}

	m2(){
	}

	m3(){
	}
}
```

=> Unit testing is used to identify weather code is working as expected or not.

=> Unit testing is used to identify bugs in the code.

=> With the help of unit testing we can identify bugs at early stage.

=> By performing unit testing we can provide quality code  to higher environments


## Note: Developer is responsible to perform unit testing in the project ##


=================================
What is isolated unit testing ?
=================================

=> Controller methods are depends on service methods and service methods depends on dao/repo methods.

=> When we are performing unit testing for controller method that time only controller method should be executed (service method shouldn't be called).


Ex:

class A {

m1() {
	
	//logic

	m2 ( );

	// logic

}

}

class B{

	m2(){
		//logic
	}

}

Note: When we are unit testing m1() method only m1() logic should be executed without calling real m2() method.


=> To perform isolated unit testing we will use Mocking.


===================
What is Mocking ?
===================

=> The process of creating substitute object for real-object is called as Mocking.

=> Mocking is the practice of creating fake (mock) objects that imitate the behavior of real objects in a controlled way. 

Note: Mock objects are required only for unit testing.

=========================
Why Do We Need Mocking?
=========================

1) Isolated unit testing

	- You want to test only your component or method, not its dependencies.

Example: When testing a service method, you don’t want the database or external API to be involved.

2) Avoiding External Dependencies

	- Real services (like APIs, DBs) might be slow, costly, or unavailable.


3) Simulating Specific Scenarios

	- You can mock unusual or error conditions (e.g., timeout, 404 error).

	- Helps test how your code behaves under different conditions.

4) Improving Test Speed
	
	- Mocks avoid real network/database calls, making tests faster.

================
Mock Frameworks	
================

=> We have several mock frameworks in the market for creating mock objects

1) Mockito 

2) Easy Mock

3) JMock

4) PowerMock


=> In Spring Boot, the default and most commonly used mocking framework is Mockito. 

=> It is fully integrated with Spring Boot's testing support and used by default when you write unit or integration tests.

=> When we add 'spring-boot-starter-test' dependency then "junit + mockito" dependencies will be available by default in project build path.

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-test</artifactId>
  <scope>test</scope>
</dependency>

================================================
Common Mockito Annotations in Spring Boot Tests
================================================

1) @Mock

2) @MockitoBean

3) InjectMocks

4) @Spy


========================
What is code coverage ?	
========================

=> The process of identifying which lines of code is unit tested and which lines of code is missed in unit testing.

=> Industry standard is minimum 80% code coverage for the project.

=> To get code coverage report we can use 'jacocco' plugin in pom.xml

Note: using SonarQube also we can get code coverage report.


========================================
Jacoco plugin configuration in pom.xml
========================================

=> Add below plugin and execute 'mvn test' goal.

Note: Code Coverage report we can find in "target/site/jacoco/index.html"

=> When our classes doesn't have business logic then we don't perform unit testing and we will exclude such classes from code coverage report.

EX: Start class, pojo classes, entities and form bindings, Config, Constants .......

--------------------------------------------------------------------------------------------
<plugin>
	<groupId>org.jacoco</groupId>
	<artifactId>jacoco-maven-plugin</artifactId>
	<version>0.8.11</version>
	<configuration>
		<excludes>
			<exclude>in/ashokit/model/**</exclude>
			<exclude>in/ashokit/Application**</exclude>
		</excludes>
	</configuration>
	<executions>
		<execution>
			<goals>
				<goal>prepare-agent</goal>
			</goals>
		</execution>
		<execution>
			<id>report</id>
			<phase>test</phase>
			<goals>
				<goal>report</goal>
			</goals>
		</execution>
	</executions>
</plugin>


==================================================
SpringBoot Rest API + Junit + Mocking + Jacoco
==================================================

@@ Git Repo : https://github.com/ashokitschool/springboot_junit_mock_app.git