# Modbus integration-test fixture — pymodbus simulator

The Modbus driver's integration tests talk to a
[`pymodbus`](https://pymodbus.readthedocs.io/) simulator running as a
pinned Docker container. One image, per-profile service in compose, same
port binding (`5020`) regardless of which profile is live. Docker is the
only supported launch path — a fresh clone needs Docker Desktop and
nothing else.

| File | Purpose |
|---|---|
| [`Dockerfile`](Dockerfile) | `python:3.12-slim-bookworm` + `pymodbus[simulator]==3.13.0` + the four profile JSONs |
| [`docker-compose.yml`](docker-compose.yml) | One service per profile (`standard` / `dl205` / `mitsubishi` / `s7_1500`); all bind `:5020` so only one runs at a time |
| [`profiles/*.json`](profiles/) | Same seed-register definitions the native launcher uses — canonical source |

## Run

From the repo root:

```powershell
# Build + start the standard profile
docker compose -f tests\ZB.MOM.WW.OtOpcUa.Driver.Modbus.IntegrationTests\Docker\docker-compose.yml --profile standard up

# DL205 quirks
docker compose -f tests\ZB.MOM.WW.OtOpcUa.Driver.Modbus.IntegrationTests\Docker\docker-compose.yml --profile dl205 up

# Mitsubishi MELSEC quirks
docker compose -f tests\ZB.MOM.WW.OtOpcUa.Driver.Modbus.IntegrationTests\Docker\docker-compose.yml --profile mitsubishi up

# Siemens S7-1500 MB_SERVER quirks
docker compose -f tests\ZB.MOM.WW.OtOpcUa.Driver.Modbus.IntegrationTests\Docker\docker-compose.yml --profile s7_1500 up
```

Detached + stop:

```powershell
docker compose -f tests\...\Docker\docker-compose.yml --profile dl205 up -d
docker compose -f tests\...\Docker\docker-compose.yml --profile dl205 down
```

Only one profile binds `:5020` at a time; switch by stopping the current
service + starting another. The integration tests discriminate by a
separate `MODBUS_SIM_PROFILE` env var so they skip correctly when the
wrong profile is live.

## Endpoint

- Default: `localhost:5020`
- Override with `MODBUS_SIM_ENDPOINT` (e.g. a real PLC on `:502`).

## Run the integration tests

In a separate shell with one profile live:

```powershell
cd C:\Users\dohertj2\Desktop\lmxopcua
dotnet test tests\ZB.MOM.WW.OtOpcUa.Driver.Modbus.IntegrationTests
```

`ModbusSimulatorFixture` probes `localhost:5020` at collection init +
records a `SkipReason` when unreachable, so tests stay green on a fresh
clone without Docker running.

## References

- [`docs/drivers/Modbus-Test-Fixture.md`](../../../docs/drivers/Modbus-Test-Fixture.md) — coverage map + gap inventory
- [`docs/v2/dev-environment.md`](../../../docs/v2/dev-environment.md) §Docker fixtures — full fixture inventory