Spring+kotlin+mongo+testcontainer

Vikas Verma
technical
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Introduction

In this project we shall see how to use testcontainer to test the repository created in mongodb As per their document Testcontainers is a Java library that supports JUnit tests, providing lightweight, throwaway instances of common databases, Selenium web browsers, or anything else that can run in a Docker container.

Prerequisit

  • Docker

Create sample project

Go to the spring initializer and create project with language as kotlin and dependencies required are webflux & reactive mongo db

Here we shall create a loan details application, where we will save loan details.

Dependency for testcontainer

We need following depencies to add testconainer in the appliation

Container Configuration

Create docker compose file for the test container we shall use the same docker-compose.yml file as we are using for the application, except we shall change the port for the test docker container. it should look like this-

Note: here we are mapping docker container port at 1234 some random port it can be any number that are available.

The file path should be src/test/resources/docker-compose-test.yml

Create a container class that extends docker compose container class be used as mongo container

The code is very simple and self explanatory, at line:2 we create a DockerComposeContainer of type SELF MongoContainer and provide path of test docker compose file.

We created it as a singleton repository and use @PostConstruct to start the container once the dependency injection is done.

That’s all we need to start with testconatainer.

Create basic structure of the application

Create a document class to save in mongo

Create an repository to access data from the DB.

Create an service class to access the loan details.

Create first test case

Let’s create our first test case as below

The test case is preety normal and same we write. There is nothing special we need to do for testcontainers here.

Run Test

Before run local test do ensure that the docker is running on your machine.

Repository

Create repository and link here.