Update opencv package error handling

platforms/opencv/camera_driver.go

@@ -1,6 +1,8 @@
 package opencv
 
 import (
+	"errors"
+
 	cv "github.com/hybridgroup/go-opencv/opencv"
 	"github.com/hybridgroup/gobot"
 )
@@ -11,7 +13,7 @@ type CameraDriver struct {
 	gobot.Driver
 	camera capture
 	Source interface{}
-	start  func(*CameraDriver)
+	start  func(*CameraDriver) (err error)
 }
 
 // NewCameraDriver creates a new driver with specified name and source.
@@ -23,15 +25,16 @@ func NewCameraDriver(name string, source interface{}) *CameraDriver {
 			"CameraDriver",
 		),
 		Source: source,
-		start: func(c *CameraDriver) {
+		start: func(c *CameraDriver) (err error) {
 			switch v := c.Source.(type) {
 			case string:
 				c.camera = cv.NewFileCapture(v)
 			case int:
 				c.camera = cv.NewCameraCapture(v)
 			default:
-				panic("unknown camera source")
+				return errors.New("Unknown camera source")
 			}
+			return
 		},
 	}
 
@@ -42,8 +45,10 @@ func NewCameraDriver(name string, source interface{}) *CameraDriver {
 
 // Start initializes camera by grabbing a frame
 // every `interval` and publishing an frame event
-func (c *CameraDriver) Start() error {
-	c.start(c)
+func (c *CameraDriver) Start() (err error) {
+	if err = c.start(c); err != nil {
+		return err
+	}
 	gobot.Every(c.Interval(), func() {
 		if c.camera.GrabFrame() {
 			image := c.camera.RetrieveFrame(1)

platforms/opencv/camera_driver_test.go

@@ -9,8 +9,9 @@ import (
 
 func initTestCameraDriver() *CameraDriver {
 	d := NewCameraDriver("bot", "")
-	d.start = func(c *CameraDriver) {
+	d.start = func(c *CameraDriver) (err error) {
 		d.camera = &testCapture{}
+		return nil
 	}
 	return d
 }
@@ -31,19 +32,12 @@ func TestCameraDriverStart(t *testing.T) {
 }
 func TestCameraDriver(t *testing.T) {
 	d := NewCameraDriver("bot", "")
-	d.Start()
-	gobot.Refute(t, d.camera, nil)
+	err := d.Start()
+	gobot.Assert(t, err, nil)
 
-	defer func() {
-		r := recover()
-		if r != nil {
-			gobot.Assert(t, "unknown camera source", r)
-		} else {
-			t.Errorf("Did not return Unknown camera error")
-		}
-	}()
 	d = NewCameraDriver("bot", true)
-	d.Start()
+	err = d.Start()
+	gobot.Refute(t, err, nil)
 }
 
 func TestCameraDriverHalt(t *testing.T) {