What is the best way I can simulate a custom SPP bluetooth device?

I'm working on an app that needs to connect to custom bluetooth hardware, and transmit between the two. I won't have access to the specific hardware until much later in development.

The Android phone needs to connect with SPP and the custom device will be in slave mode.

I've looked at things such as RealTerm, but it looks complicated, and I'm considering just using a second Android device to act as the slave.