BankNext Case Study -Junit Mockito Automation

Automatically produce Junits for your SpringBoot application

Problem Statement-

BankNext’s massive production environment has more than 300 live microservices. Multiple squad’s working concurrently on these svcs heightens the risk of breaking functionality. Adding Junits & code coverage manually to existing and new code is arduous & painfully slow.

Challenges w/ Manual Junits-

1. Time-intensive activity to write proper useful Junits manually.
2. Lacks standardization because each one takes different approaches.
3. Deficient/incorrect Junits are created due to lack of time.
4. Manual sync’up of existing Junits due to changing code is impractical.
5. Writing Junits manually for legacy code is a nightmare.
6. Least priority is allotted to Junits due to deadlines, hence get skipped.
7. Code quality suffers immensely & technical debt piles up.

Solution : Junit-Mockito Automation

1. GitHub : https://github.com/vijayredkar/junit-mockito-automation
2. Automation takes in the Class name & creates a legal working Junits.
3. These generated Junits contains the necessary Mockito mocks.
4. Handles Junits for RestControllers, Services, Handlers, Kafka classes etc.
5. Thus accomplishes > 70% code coverage in almost all scenarios.

Automation Capabilities -

1. Works for both SpringBoot 2.x & 3.x Maven based applications.
2. Almost zero setup effort.
3. Takes the local path of your application & very basic user inputs.
4. Utilizes Reflection utils to deduce application structure details.
5. Seamlessly identifies the required Mockbeans.
6. Automatically generates “When-Then” Mockito mocks.
7. Generates Jacoco code coverage reports.

Structure of a Legal Junit-

1. Mandatory portions : 3
   - invoke the target test method
   - mock any interaction that are external to this class
   - check the actual output matches the expected assert/verify
2. Identify & declare all external classes as MockBeans
3. Stub the expected responses from these MockBean interactions
4. Below are the ground rules for a basic legal working Junit

Junit-Mockito  Ground Rules

1- target mtd to be tested createCustomer is a void returnType   
2- external mtd invoked .delete     is a void returnType
3- when-then   :  doNothing whenInvoke .delete
4- assertion    :  verify .delete called 1 times  

1- target mtd to be tested createCustomer is a void returnType   
2- external mtd invoked .save          is a Customer returnType
3- when-then   :  when  save then return new Customer
4- assertion    :  verify .save called 1 times

1- target mtd to be tested createCustomer is a Customer returnType   
2- external mtd invoked .save          is a Customer returnType
3- when-then   :  when  save then return new Customer
4- assertion    :  assert result instanceof Customer / Customer is not null

1- target mtd to be tested createCustomer is a Customer returnType   
2- external mtd invoked .findAll          is a List returnType
3- when-then   :  when findAll then return new ArrayList
4- assertion    :  assert result instanceof List / List.size >0

Automation Demo -

Automation Demo Videos

cd C:\Vijay\Java              [your local machine path]
git clone https://github.com/vijayredkar/junit-mockito-automation.git

# My final directory structure
# C:\Vijay\Java\AutomationJunitMockito\appsetup
# C:\Vijay\Java\projects\junit-mockito-mgt\test-projects\junit-automation 

cd C:\Vijay\Java\AutomationJunitMockito\appsetup
setup.bat

------- Demo Steps ------
https://vijayredkar.medium.com/banknext-case-study-junit-mockito-automation-ac9f6b72cfcc
https://github.com/vijayredkar/junit-mockito-automation


C:\Vijay\Java\AutomationJunitMockito\appsetup

demo scenario -1
com.banknext.customer.mgt.service.CustomerServiceImplType1   
com.banknext.customer.mgt.controller.CustomerMgtControllerType1 

demo scenario -2
com.banknext.customer.mgt.service.CustomerServiceImplType2   
com.banknext.customer.mgt.controller.CustomerMgtControllerType2                 

demo scenario -3
com.banknext.customer.mgt.event.publisher.CustomerTxnPublisherType1             
com.banknext.customer.mgt.event.consumer.CustomerTxnConsumerType1               

demo scenario -4
https://github.com/bezkoder/spring-boot-h2-database-crud/tree/master
cd C:\Vijay\Java\projects\junit-mockito-mgt\test-projects
#git clone https://github.com/bezkoder/spring-boot-h2-database-crud.git
cd C:\Vijay\Java\projects\junit-mockito-mgt\test-projects\spring-boot-h2-database-crud
mvn clean install

cd C:\Vijay\Java\AutomationJunitMockito\appsetup
run setup.bat


cd C:\Vijay\Java\projects\junit-mockito-mgt\test-projects\spring-boot-h2-database-crud
mvn clean install
import in Eclipse
add POM dependencies
check current Jacoco code coverage
 

continue automation run 
check/adjust generated Junits
check current Jacoco code coverage
cd C:\Vijay\Java\projects\junit-mockito-mgt\test-projects\spring-boot-h2-database-crud

check new Jacoco code coverage

run all tests 
cd C:\Vijay\Java\projects\junit-mockito-mgt\test-projects\spring-boot-h2-database-crud
mvn clean install
check again all Jacoco code coverage


C:\Vijay\Java\projects\junit-mockito-mgt\test-projects\spring-boot-h2-database-crud\src\main\java\com\bezkoder\spring\jpa\h2
com.bezkoder.spring.jpa.h2.controller.TutorialController
com.bezkoder.spring.jpa.h2.model.Tutorial
TutorialController

Before & After Automation Run -

CodeCoverage Results

Conclusion -

1. BankNext saves enormous time & effort w/ automatic Junit creation.
2. This translates directly in to saving project expenses.
3. Code coverage increases immensely.
4. Team is able to completely focus on real development activities.
5. Junits added/maintained consistently w/ almost zero manual effort.
3. Technical debt reduces vastly.
4. Greatly enhances confidence in applications deployed to production.