> ## Creating test templates

> Fetch the complete documentation index at: https://antithesis.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

---

This page explains how to create test templates, and how Antithesis recognizes and runs them.

See [test commands](/docs/product/test_templates/test_composer_reference/) for details of available test commands.

## Creating a test template

A test template is a directory that lives under `/opt/antithesis/test/v1/` and contains scripts called [test commands](/docs/product/test_templates/test_composer_reference/). For convenience, we sometimes refer to `/opt/antithesis/test/v1/` as the "test directory".

Here's an example file structure:

```
/opt/antithesis/test/v1/               ← test directory
├── main/                              ← a test template
    ├── first_setup.py
    ├── parallel_driver_produce.py
    ├── parallel_driver_consume.py
    ├── serial_driver_compact.sh
    ├── anytime_health.py
    ├── eventually_verify.py
    ├── finally_consistency.sh
    ├── helper_utils.py                ← ignored by Antithesis (helper_ prefix)
    └── helper_modules/                ← ignored by Antithesis (helper_ prefix)
        └── kafka_client.py
```

You can place your test templates under `/opt/antithesis/test/v1/` inside any of your containers, but we recommend placing it in a dedicated container rather than in your system containers.

Multiple containers can also share a test template, see below.

> **Note**
>
> Any container with test templates must be kept running (e.g., via `sleep infinity` in the entrypoint). Do not use a test command as the container entrypoint.

## Using multiple test templates

You can add multiple test templates under `/opt/antithesis/test/v1/`. By placing multiple test templates in the test directory, you can use different testing strategies during a single Antithesis run.

Here's an example:

```
/opt/antithesis/test/v1/
├── basic/                            ← simple producer/consumer tests
│   ├── first_create_topic.py
│   ├── parallel_driver_produce.py
│   └── parallel_driver_consume.py
├── transactional/                    ← transaction-focused tests
│   ├── first_setup_tx.py
│   ├── parallel_driver_tx_write.py
│   └── finally_tx_verify.py
└── stress/                           ← high-throughput stress test
    └── singleton_driver_load.py
```

Antithesis selects **exactly one** template per execution history. Test commands in `basic/` will never run alongside test commands in `transactional/` or `stress/`.

This means all commands in a single test template should be compatible with each other, but you can include incompatible commands in different test templates.

## Sharing test templates across multiple containers

If containers `client-a` and `client-b` both have a directory called `/opt/antithesis/test/v1/main/`, Antithesis treats both instances of `main` as a single test template with commands spread across both containers. Each command runs inside the container where it is defined.

## Helper files

Subdirectories and files with a `helper_` prefix in their name are ignored by Antithesis. Use this prefix for shared libraries, utility modules, and configuration files that your test commands require.