Implement list of capabilities for gateway.

gateway.go

@@ -105,8 +105,19 @@ type gateway struct {
 }
 
 func (g *gateway) Capabilities() []da.Capability {
-	//TODO implement me
-	panic("implement me")
+	caps := map[da.Capability]struct{}{capabilities.DeviceRemovalFlag: {}, capabilities.EnumerateDeviceFlag: {}}
+
+	for _, c := range factory.Mapping {
+		caps[c] = struct{}{}
+	}
+
+	var capSlice []da.Capability
+
+	for c := range caps {
+		capSlice = append(capSlice, c)
+	}
+
+	return capSlice
 }
 
 func (g *gateway) Self() da.Device {

gateway_test.go

@@ -100,3 +100,15 @@ func Test_gateway_Devices(t *testing.T) {
 		assert.Contains(t, devices, gw.Self())
 	})
 }
+
+func Test_gateway_Capabilities(t *testing.T) {
+	t.Run("contains expected capabilities", func(t *testing.T) {
+		gw := gateway{}
+
+		caps := gw.Capabilities()
+
+		assert.Contains(t, caps, capabilities.DeviceRemovalFlag)
+		assert.Contains(t, caps, capabilities.EnumerateDeviceFlag)
+		assert.Contains(t, caps, capabilities.ProductInformationFlag)
+	})
+}