public void TestAllDevices()
{
var deviceManager = new DeviceManager();
Assert.Empty(deviceManager.AllDevices());
var moq1 = new Mock <IDevice>();
moq1.Setup(device => device.Id).Returns("test1");
deviceManager.RegisterDevice(moq1.Object);
Assert.Contains(moq1.Object, deviceManager.AllDevices());
var moq2 = new Mock <IDevice>();
moq2.Setup(device => device.Id).Returns("test2");
deviceManager.RegisterDevice(moq2.Object);
Assert.Contains(moq1.Object, deviceManager.AllDevices());
Assert.Contains(moq2.Object, deviceManager.AllDevices());
}