I2C slave simulation

[PeterR]

I have a project which has a complex analogue I2C slave device.
I want to automate tests & build in some determinism.

The device is a set of I2C registers. Some registers hold the analogue value, others are used to configure.
We use a hard coded configuration so it is enough just to check that configuration matches register writes.

I could host test and stub the I2C interface of course. There are many other ESP32 hardware and IDF resources used however.
Another approach would be to automate target testing. All I have to do is simulate an I2C slave with the ability to read/write registers which match my complex analogue device.

There are PC I2C to USB dongle. As far as I can tell these are all I2C masters however.
Has anyone else done this before? What did you use? I am reluctant to build my own device. I could connect my UUT to another ESP32 I2C and use (for example) an Webserver to read/update registers. I want to buy in however.