In this tutorial, we are going to implement unit testing in a springboot REST API project. We are going to implement unit testing on an Employee Management System with the basic Create, Read, Update and Delete Functionality. 

 - Testing the entire application, its external dependencies in a production like environment

 - Testing an application from a users point of view

 -  Ensuring different modules of an application work together correctly.

 - Testing individual components of an application for example methods or classes in isolation. For this tutorial we are going to focus on this.

To set up the project use a spring initializer. Go to https://start.spring.io.Add the following dependencies to your project: Spring Web, Spring Data JPA, H2 Database, SpringBoot Dev Tools, Springboot Test. Also for this project we are going to use Java 17 , maven and Jar for packaging.

Create an Employee Class with the following fields: id, firstName, lastName, Department and email. Here is the Employee Class with the Getters and Setters

Step 6: Create the ResourceNotFoundException Class

This is how the folder Structure looks like:

Feel  Free to Access the code at this repository: https://github.com/kodaschool/unit-testing-springboot

Each project generated by the springboot has testing in mind. The Package below has all the libraries required to do unit testing. This dependency comes by default when generating a springboot project. Check the 

Inspect the dependencies it comes bundled with by hitting

 - De- facto standard for unit testing in java

- Utilities and integration test support for Springboot applications

It is used to load the application context and run tests with Spring Boot features.

 annotation when you need Spring Boot features.

It creates the application context used in tests through 

It allows you to test the integration of different components and services.

It can be configured to load specific classes, set the environment, and set properties.

It provides support for different web environment modes, including the ability to start a fully running web server

 is used to test JPA components in Spring Boot.

It disables full auto-configuration and applies only configuration relevant to JPA tests.

By default, it uses an embedded in-memory database for testing.

The application context contains all JPA components, including the in-memory database.

Each test method runs in its own transaction and is rolled back after execution.

Ensure you use this annotation when testing the repository layer.

Useful for testing JPA repositories and custom JPA query methods.

 classes and configures Spring Data JPA repositories.

SQL queries are logged by default, but this can be disabled.

 for full application configuration with an embedded database.

Allows you to send HTTP requests to your controller and check the response, without actually starting a web server or making network requests. This makes it a fast and efficient way to test your controller logic.

Automatically configures MockMvc for you, so you don't have to manually set it up.

 Configures a test database for testing database-related functionality.

 annotation is used to mark a method that should be executed before each test method in the test class.

This annotation is typically used to set up the initial state or prepare the environment required for each test method.

Common tasks performed in a method annotated with 

 include initializing objects, setting up mock objects, or preparing test data.

 are executed before each test method, ensuring that the test environment is consistent and isolated for each test.

 annotation is used to mark a method that should be executed after each test method in the test class.

This annotation is typically used to clean up resources, reset the state, or perform any necessary teardown tasks after each test method.

 include releasing resources, closing connections, or resetting objects to their initial state.

 are executed after each test method, ensuring that any cleanup or teardown tasks are performed consistently after each test.

Repeats a test a specified number of times.

Executes sql scripts before and after a test

a) Use Test Driven Development Approach ie write the tests before writing the actual code or write them in parallel.

b) Add Tests To your CI CD pipeline and send notifications in case of failure.

c) Ensure tests work in isolation without interfering with each other

d) Ensure a high test coverage of greater than 80% by using test coverage tools like Sonacube and Jacoco .

e) Use meaningful naming convections for testcases. For example 

- Ensure you have a h2 database whose scope is test that will be used as an in memory database in the 

- Create a  directory inside the test folder and choose resources and configure the h2 database for test inside the 

Here's what each part of the h2 URL means:

: This is the protocol prefix for connecting to an H2 database using JDBC.

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springboot Tutorials

Writing Unit Tests for REST APIs with Springboot

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