Simulation API - Suggestions and Requirements

We have several PRs suggesting the addition of a simulation GPIO Driver to simplify development and testing without actual hardware (see #1827 and #1823). The team has agreed that such a simulation is desirable, but it should include, at least as possible further extensions, simulation components for other hardware interfaces, particularly I2C, SPI or PWM.

Suggested class structure:

namespace Iot.Devices.Simulation
{
    public class SimulationBoard : Board
    {
        // ....
       public override GpioController CreateGpioController()
       {
           return new GpioController(PinNumberingScheme.Logical, new SimulationGpioDriver(NumberOfPinsToSimulate));
       }
    }

    public class SimulationGpioDriver : GpioDriver
    {
    // ....
    }

    public class SimulationI2cBus : I2cBus
    {
    // ...
    }
    // ....
}

To simulate the behavior of the actual hardware, the simulation devices should have a “backend” interface that allows connecting a simulation implementation, either by having events to connect to, such as showcased here, or something like a REST api to connect an external simulation Gui to. That simulation GUI could then simulate the wiring between inputs/outputs or simulate devices on the I2C bus.

Suggestions or improvements?

I do not expect that a first implementation would be able to support all cases, but it shouldn’t block further development towards such a scenario.

@HumJ0218 @mcNets

[pgrawehr]

From @raffaeler’s suggestions on #383:

The goals for this proposal:

• ability to mock all the devices for testing purposes without having to use Moq or similar frameworks
• ability to log the sequence of I/O writes
• ability to create a framework to replay a sequence to simulate a complete I/O handshake without any connected device
• ability to run the application on a host which doesn’t have any device connected. For example, this is useful to test the other parts of the application on Windows and later run the real one on the embedded board.

[krwq]

ref: https://github.com/dotnet/iot/issues/383