Assumption

1. There is and should have only one CEO on the top level. If there is no CEO, the service will return an error with status code of 500.
2. The manager ID with the CEO is set to 0
3. A invalid employee has an employee ID of less than 0

Project structure

src/main/java/: Serves as the java back-end src/main/resources/static/: Serves as the Angular 2+ front-end (This is a build version. To view the front-end source code: https://github.com/yliu138/employee-hierarchy-coding-challenge-client)

Technology used

1. Spring boot
2. Web
3. H2 (In-memory DB) in production, H2 is designed for testing only but in this example, for demonstration, this is used for the runtime database as well.
4. JPA
5. JUnit, Mockito, Jacoco
6. Maven
7. Angular 4
8. Protractor, Jasmine, Karma
9. Webpack

How to start

Terminal

1. Install maven
2. Use this code to start the back end

	mvn spring-boot:run -q

Eclipse

1. Make sure maven is in the environment path.
2. Import this project into Eclipse
3. In the quick access, normally on the top right corner, type in run Spring Boot app.
4. You will be able to run the application

After server is running, you can view the employee hierarchy visually by accessing the root path: http://localhost:8080(or other ports)

Test

Back-end test

Code coverage test

1. tools: Jacoc and Sonar

How to start the test

1. Eclipse (Recommended): JUnit test

2. Terminal

	mvn clean test

h2 test

There are some pre-populated data in data.sql under the folder resources/. Please feel free to add more tests or modified the tests manually as well by accessing the h2 console: http://localhost:8080/h2-console.

Remember to put jdbc:h2:mem:testdb in the JDBC URL field, and hit "Connect" directly

Add more data running e.g.,

	insert into employee(employeeId, name, managerId)
	values(600, 'Andy', 190);

Design pattern used

1. IoC: mainly depedency injection
2. Factory
3. Singleton