[ANN] Running Real Docker Containers in OCaml Tests

Ecosystem
, ,
1

Hi everyone,

I’ve been working on a project called testcontainers-ocaml, which brings Testcontainers style integration testing to OCaml.

The idea is simple:

Instead of mocking infrastructure (Postgres, Redis, Kafka, etc.), start real Docker containers inside your test suite and tear them down automatically.

Why?

In many OCaml projects, integration tests either:

  • Rely on mocks

  • Depend on globally running services

  • Or are skipped entirely in CI

Mocks are useful, but they don’t catch issues like:

  • Schema mismatches

  • Connection pool behavior

  • Real networking failures

  • Startup timing problems

  • Migration issues

Spinning up disposable containers per test gives us:

  • Isolated test environments

  • No shared global state

  • CI reproducibility

  • Real infrastructure behavior

Current Status

The project is currently incubating under the Docker organization.

I’m still actively shaping the API and would really appreciate feedback from the OCaml community on:

  • API ergonomics

  • Prebuilt modules (Postgres, Redis, etc.)

  • Testing best practices in OCaml

If anyone here has experience with integration testing patterns in OCaml, I’d love to hear thoughts.

Thanks!

5 Likes