Testcontainers maven example

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. You can also check the latest version available on Maven Central. Using Maven you can add the following to dependencyManagement section in your pom. Using Gradle 5. As such, these libraries are 'shaded' into the core testcontainers JAR and relocated under org.

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Testcontainers is on Github Sponsors! Please consider sponsoring us to sustain the project and help us improve it further.

Copyright for that class remains with the original authors. This project was initially inspired by a gist by Moshe Eshel. License Attributions Copyright. Testcontainers make the following kinds of tests easier: Data access layer integration tests : use a containerized instance of a MySQL, PostgreSQL or Oracle database to test your data access layer code for complete compatibility, but without requiring complex setup on developers' machines and safe in the knowledge that your tests will always start with a known DB state.

Any other database type that can be containerized can also be used. Application integration tests : for running your application in a short-lived test mode with dependencies, such as databases, message queues or web servers.

Each test can get a fresh instance of the browser, with no browser state, plugin variations or automated browser upgrades to worry about.

Implementing Integration Tests Using Testcontainers

And you get a video recording of each test session, or just each session where tests failed. Much more! Check out the various contributed modules or create your own custom container classes using GenericContainer as a base.

Gradle implementation platform 'org. Cirrus CI.Work fast with our official CLI. Learn more. If nothing happens, download GitHub Desktop and try again. If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again. Often applications being integration tested must interact with other software but doing so can be tricky. Sharing a database instance will have side effects that complicate or break tests.

Mocked databases are not representative of the production environment.

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The solution shown here uses containerisation to provide a private database instance. The Github repository contains a complete working example test used as the source for all code snippets in this example.

Most developers see the merits of integration testing, but there are practical considerations when creating services like databases to test against. This is especially true for components that are not themselves implemented in Java and therefore cannot be launched directly as Java libraries. Instead of running a shared or mocked database, run a real instance of the database within a Docker container.

This can be created automatically before the test suite is run and removed afterwards. The approach has the following merits:. The example makes use of the Testcontainers libraries to automatically start and stop a Docker Compose environment before and after the suite of tests is run.

Docker is a tool for containerising applications, and Docker Compose is a tool for coordinating a suite of containerised applications. In a complex test one might wish to initialise different software e.

Docker compose is the tool that Testcontainers uses internally and therefore must be provided with a suitable docker compose configuration file.

Also provided is a script named init. To test this configuration before trying to incorporate it into the integration test, put the two files alone in a directory and run docker-compose from that directory thus:. Although this output lists the ports that the database has opened, this is from the perspective of the container. From the host environment you can view the status of the running service s using the process listing command from another terminal session:. To shutdown the docker container hit Ctrl-C in the terminal session currently running docker-compose or run docker-compose down from another terminal session.

Once the integration test is running on a build server, there may be other tests or other instances of the same test running simultaneously.

If the port number was predetermined then the tests would fail if the desired port was already in use. Instead you can instruct Docker to assign an ephemeral port number an unused port above on the host computer and bridge that to the MySQL protocol port on the container.Tests are an integral part of the development process.

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If we talk in terms of functional or integration tests, more often than not, they depend upon some infrastructure, like some kind of database, messaging queue, distributed cache, etc. Usually, when we want to create integration tests e. Although, this is easy to set up and get started, it carries some drawbacks and challenges with it.

testcontainers maven example

If tests pass against the in-memory database, that does not necessarily mean that tested code will work correctly against the production database. This can be due to the fact that some vendor-specific things of production database are simply not supported by the in-memory database. To overcome this issue, one rout is to implement some workarounds, or simply not cover that part with tests, but this is not ideal, to say the least, because we end up rewriting code to accommodate tests or risk leaving code untested.

Those are just a few examples related to RDBs, in case that we have a hybrid setup with NoSQL database, messaging queue, cache… things became more challenging really fast. One option to overcome these issues is to run our tests against the specific production-like environment. Since this environment is probably already present as part of deployment and delivery process, this seems like a solid option for testing needs.

But there are some drawbacks, main are that this means that we cannot easily run a test from a local development environment for e. This environment might not always be available it might be used for performance testing, or environment simply goes down.

Also, when we deploy our application and tests onto the environment and run tests there, the feedback loop slows down, so any errors are detected and fixes are implemented much later. Basic knowledge of those technologies is assumed, but in any case, core principles and ideas presented here should be applicable when using testcontainers with any other technology stack.

There are two ways to use testcontainers: managed by Java test code, or managed by a build tool like Gradle. The approach described here will focus on Java code usage.


The second approach is outside of the scope of this post, so for more info, check out the official documentation and examples provided by the community. The first step is to add a dependency to the project. There is a generic module testcontainers dependency, which supports generic containers, docker-compose, etc.

Dependency is added to build a Gradle file:. Now when we have testcontainers on our classpath, the easiest way to initialize our Postgres container is to create an instance, like so:. A container is, by default, started on a random port to avoid potential conflicts.

We can customize username, password and database name during initialization:. But we cannot reconfigure port. Also, the port is assigned when the container is started, so there is no way to know which port is going to be used before we actually start the container. This presents a challenge, assuming that the application has an instance configured to communicate with the database.

In that case, we also need to configure the datasource instance for our integration tests. In the example above, we fixed port onso now, before we start the container, we can configure our datasource instance using JDBC connection string:.

Taking that into the account, we must leave port assignment dynamic but somehow initialize datasource instance, and with it, ideally, the Liquibase instance, which can be used to re create the database schema. This would require the set up of application context after the container has been started. So, for example, we can have following test configuration class:.We're a place where coders share, stay up-to-date and grow their careers. I had the following requirements for this task:.

testcontainers maven example

For this task, I found the awesome project: Test containers. The project describes itself as the following:. With this blog post, we'll use Testcontainers to write integration tests with JUnit using a real database meaning not mocked or in-memory for a Spring Boot application. With Testcontainers you can use a ClassRule or Rule on each of your integration tests and define the Docker image for your test valid for JUnit 4.

To run the integrations tests after your unit tests, simply add maven-failsafe-plugin to your project. In addition, make sure your integration tests have IT as a postfix:. Let's start with the integration test each Spring Boot application contains out-of-the-box. This integration test verifies that Spring can create the context and start the application. As our application requires a PostgreSQL to be available during startup, we can provide one using Testcontainers.

Write Spring Boot integration tests with Testcontainers (JUnit 4 & 5)

Overriding the properties to use the PostgreSQL database spawned by Testcontainers is as easy as the following:. If your application uses JUnit 5, you can't use the ClassRule anymore. Fortunately, Testcontainers provides a solution to write tests with JUnit Jupiter:. Robson Neres - Mar Hafiz Jaafar - Mar 6. DEV Community is a community ofamazing developers We're a place where coders share, stay up-to-date and grow their careers.

Create new account Log in. Listings Podcasts Videos Tags More I had the following requirements for this task: The integration tests should use the same database as in production referring to the Twelve-Factor App I wanted to keep my environment during the tests as similar as possible to the production environment The tests should not need any pre-setup before running e.While Testcontainers is tightly coupled with the JUnit 4.

The extension finds all fields that are annotated with Container and calls their container lifecycle methods methods on the Startable interface.

Containers declared as static fields will be shared between test methods. They will be started only once before any test method is executed and stopped after the last test method has executed. Containers declared as instance fields will be started and stopped for every test method. Note: This extension has only been tested with sequential test execution.

Using it with parallel test execution is unsupported and may have unintended side effects.

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To define a restarted container, define an instance field inside your test class and annotate it with the Container annotation. Shared containers are defined as static fields in a top level test class and have to be annotated with Container.

Note that shared containers can't be declared inside nested test classes. This is because nested test classes have to be defined non-static and can't therefore have static fields. Note that the singleton container pattern is also an option when using JUnit 5. Since this module has a dependency onto JUnit Jupiter and on Testcontainers core, which has a dependency onto JUnit 4. This extension has only be tested with sequential test execution. Extension Jupiter integration is provided by means of the Testcontainers annotation.

Gradle testImplementation "org.The canonical reference for building a production grade API with Spring. If you have a few years of experience in the Java ecosystem, and you're interested in sharing that experience with the community and getting paid for your work of coursehave a look at the "Write for Us" page. Cheers, Eugen. In this tutorial, we'll be looking at Java TestContainers library. It allows us to use Docker containers within our tests. As a result, we can write self-contained integration tests that depend on external resources.

We can use any resource in our tests that have a docker image. Therefore, we can run them as containers within our tests. TestContainers library can be used with Java 8 and higher. There are also modules for specialized containers.

Also, we need Docker to run containers. Refer to Docker documentation for installation instructions. Then, we configure it with builder methods:. The container will be destroyed after all methods are executed.

And it will stop the container when that test method finishes. We can use IP address and port to communicate with the process running in the container :.

There are several usage modes of the test containers. TestContainers library has also rule definitions with specialized functionality. Although we can run them as generic containers, the specializations provide extended convenience methods.

Let's assume we need a database server for data-access-layer integration tests. We can run databases in containers with the help of TestContainers library. It is also possible to run PostgreSQL as a generic container.

But it'd be more difficult to configure the connection. Another useful scenario is to run containers with web browsers.

Then, we manage them with RemoteWebDriver. Then, we use DockerComposeContainer rule. This rule will start and run services as defined in the compose file. We use getServiceHost and getServicePost methods to build connection address to the service:. We saw how we could use TestContainers library. It eases developing and running integration tests.

They give more functionality for specific use cases. Finally, code samples here can be found over on GitHub. Persistence The Persistence with Spring guides.

testcontainers maven example

Security The Spring Security guides. Full Archive The high level overview of all the articles on the site.Related Classes. Arrays java. File java. Collections java. UUID java. Collectors java. StandardCharsets org. BeforeClass java. Consumer java. Duration com. ImmutableList javax. Nullable com. Files com. Charsets com. Hashing org. Duration org. GenericContainer org.

PostgreSQLContainer org. Wait org. BindMode com. CreateContainerCmd org. FixedHostPortGenericContainer com. PortBinding com. Image org.

How to access docker container application from outside 🐳

OutputFrame org. Java Code Examples for org. Network The following examples show how to use org.

testcontainers maven example

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