Add test to validate Linux camera label rule

pkg/driver/camera/camera_linux.go

@@ -73,42 +73,40 @@ type camera struct {
 
 func init() {
 	discovered := make(map[string]struct{})
+	discover(discovered, "/dev/v4l/by-path/*")
+	discover(discovered, "/dev/video*")
+}
 
-	discover := func(pattern string) {
-		devices, err := filepath.Glob(pattern)
+func discover(discovered map[string]struct{}, pattern string) {
+	devices, err := filepath.Glob(pattern)
+	if err != nil {
+		// No v4l device.
+		return
+	}
+	for _, device := range devices {
+		label := filepath.Base(device)
+		reallink, err := os.Readlink(device)
 		if err != nil {
-			// No v4l device.
-			return
+			reallink = label
+		} else {
+			reallink = filepath.Base(reallink)
+		}
+		if _, ok := discovered[reallink]; ok {
+			continue
 		}
-		for _, device := range devices {
-			label := filepath.Base(device)
-			reallink, err := os.Readlink(device)
-			if err != nil {
-				reallink = label
-			} else {
-				reallink = filepath.Base(reallink)
-			}
-
-			if _, ok := discovered[reallink]; ok {
-				continue
-			}
 
-			discovered[reallink] = struct{}{}
-			cam := newCamera(device)
-			priority := driver.PriorityNormal
-			if reallink == prioritizedDevice {
-				priority = driver.PriorityHigh
-			}
-			driver.GetManager().Register(cam, driver.Info{
-				Label:      label + LabelSeparator + reallink,
-				DeviceType: driver.Camera,
-				Priority:   priority,
-			})
+		discovered[reallink] = struct{}{}
+		cam := newCamera(device)
+		priority := driver.PriorityNormal
+		if reallink == prioritizedDevice {
+			priority = driver.PriorityHigh
 		}
+		driver.GetManager().Register(cam, driver.Info{
+			Label:      label + LabelSeparator + reallink,
+			DeviceType: driver.Camera,
+			Priority:   priority,
+		})
 	}
-
-	discover("/dev/v4l/by-path/*")
-	discover("/dev/video*")
 }
 
 func newCamera(path string) *camera {

pkg/driver/camera/camera_linux_test.go

@@ -0,0 +1,62 @@
+package camera
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/pion/mediadevices/pkg/driver"
+)
+
+func TestDiscover(t *testing.T) {
+	const (
+		shortName  = "video0"
+		shortName2 = "video1"
+		longName   = "long-device-name:0:1:2:3"
+	)
+
+	dir, err := ioutil.TempDir("", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir)
+
+	byPathDir := filepath.Join(dir, "v4l", "by-path")
+	if err := os.MkdirAll(byPathDir, 0755); err != nil {
+		t.Fatal(err)
+	}
+	if err := ioutil.WriteFile(filepath.Join(dir, shortName), []byte{}, 0644); err != nil {
+		t.Fatal(err)
+	}
+	if err := ioutil.WriteFile(filepath.Join(dir, shortName2), []byte{}, 0644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Symlink(
+		filepath.Join(dir, shortName),
+		filepath.Join(byPathDir, longName),
+	); err != nil {
+		t.Fatal(err)
+	}
+
+	discovered := make(map[string]struct{})
+	discover(discovered, filepath.Join(byPathDir, "*"))
+	discover(discovered, filepath.Join(dir, "video*"))
+
+	drvs := driver.GetManager().Query(func(d driver.Driver) bool {
+		return d.Info().DeviceType == driver.Camera
+	})
+	if len(drvs) != 2 {
+		t.Fatalf("Expected 2 driver, got %d drivers", len(drvs))
+	}
+
+	expected := longName + LabelSeparator + shortName
+	if label := drvs[0].Info().Label; label != expected {
+		t.Errorf("Expected label: %s, got: %s", expected, label)
+	}
+
+	expectedNoLink := shortName2 + LabelSeparator + shortName2
+	if label := drvs[1].Info().Label; label != expectedNoLink {
+		t.Errorf("Expected label: %s, got: %s", expectedNoLink, label)
+	}
+}