Testcontainers
Testcontainers helps developers run automated tests against temporary, containerised databases and services without manually preparing and maintaining separate test environments.
Why it caught my attention
Integration tests often depend on services that are awkward to install, configure and keep consistent across machines. Testcontainers makes those dependencies part of the test itself, so developers can check how applications behave with real databases and services without maintaining permanent test environments.
What problem does this actually solve?
Testcontainers could be worth considering if you recognise any of these challenges.
Tests rely on simulated services
Mocked dependencies can miss real database or service behaviour. Testcontainers enables testing against actual containerised software.
Setting up dependencies takes time
Developers repeatedly install and configure databases or supporting services. Tests can provision these dependencies automatically.
Test environments behave differently
Differences between developer machines and build servers cause inconsistent results. Container definitions help standardise test dependencies.
Shared test data causes failures
Persistent services accumulate data and configuration changes. Disposable containers provide fresh environments when tests require isolation.
Is this a good fit for you?
A quick way to see if Testcontainers is relevant for your situation.
- You develop applications that depend on relational databases, message brokers or other services.
- You want integration tests to exercise real dependencies rather than only mocks.
- Your developers need repeatable test environments across different machines.
- You run automated integration tests within continuous integration pipelines.
- You want test dependencies defined alongside your application testing code.
- Your testing consists entirely of isolated unit tests without external dependencies.
- Your execution environment cannot provide access to a compatible container runtime.
How does it work?
In practice, the workflow looks something like this:
Include the Testcontainers library for your programming language in your project and ensure a compatible container runtime is available.
Specify dependencies such as PostgreSQL, Redis or Kafka using available modules or suitable container images within your test code.
Run your tests. Testcontainers starts the required services, waits for configured readiness conditions and makes connection details available to your application.
Your test framework executes application checks using the containerised services, helping reveal integration problems that simulated dependencies might miss.
When the test session finishes, Testcontainers normally removes its temporary containers, leaving the environment ready for subsequent runs.
What else should I know?
A few important things to be aware of before you investigate further.
A compatible runtime is required
Tests need access to a supported Docker-compatible container runtime, locally or through Testcontainers Cloud.
Container startup adds execution time
Starting services and downloading images can increase test duration, particularly on initial runs or constrained build agents.
CI environments need suitable configuration
Build runners must support container execution or connect to an appropriate remote runtime, which may require additional configuration.
Open-source libraries and commercial services differ
The core libraries are open source; optional Desktop and Cloud offerings have separate features, account requirements and commercial terms.
Think Testcontainers could fit your environment?
Visit the Testcontainers website to find out more, request a demo or speak to their team.
Something you'd like to know about Testcontainers?
Is there something I haven't covered in my research? Send me your question and I'll look into it and reply personally by email.