This is a part of implementation code pick up from a Internal reimbursement system. you should write unit test for it to make sure it can work in production.

• ** Write test cases after clearly understanding the implemented code**
• ** Complete tests in the existing test file and ensure that the test coverage of the test category of this test file is 100%**
• Unit testing should cover all core business logic
• Make unit test refactoring with small steps
• ** Submit code in small steps with a comment on meaning **
• Complete unit tests on the corresponding file under the src/test catalog of project

• Java 8
• Intellj IDEA
• JUnit 5
• AssertJ 3.10.0
• Gradle

• You can fork the following github repository as starting point
• Please submit your own github repository address in the answer field.

• Implement ./gradlew clean test under root catalogue and view test result

• You should implement the test code and push your repo to github repo named unit-test-basic.
• Commit your repostory link to complete this Question.