Add test to validate Linux camera label rule

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)
+	}
+}