veyron/services/mgmt/device/impl: fix unit test

go/vcl/2608 broke the device manager unit test by renaming the test principal
from test-principal to test-blessing.

Change-Id: I953fd80420b163b82ee13fde5a9bbcb22bdfc583
diff --git a/lib/testutil/init.go b/lib/testutil/init.go
index 9e47b5f..4e328b3 100644
--- a/lib/testutil/init.go
+++ b/lib/testutil/init.go
@@ -22,7 +22,10 @@
 	"v.io/core/veyron2/vlog"
 )
 
-const SeedEnv = "VEYRON_RNG_SEED"
+const (
+	SeedEnv      = "VEYRON_RNG_SEED"
+	TestBlessing = "test-blessing"
+)
 
 // Random is a concurrent-access friendly source of randomness.
 type Random struct {
@@ -108,7 +111,7 @@
 		return ctx, shutdown
 	}
 	var err error
-	if ctx, err = veyron2.SetPrincipal(ctx, tsecurity.NewPrincipal("test-blessing")); err != nil {
+	if ctx, err = veyron2.SetPrincipal(ctx, tsecurity.NewPrincipal(TestBlessing)); err != nil {
 		panic(err)
 	}
 	return ctx, shutdown
diff --git a/services/mgmt/device/impl/impl_test.go b/services/mgmt/device/impl/impl_test.go
index 68ea84a..d146f15 100644
--- a/services/mgmt/device/impl/impl_test.go
+++ b/services/mgmt/device/impl/impl_test.go
@@ -609,7 +609,7 @@
 	instance1ID := startApp(t, ctx, appID)
 
 	instanceDebug := debug(t, ctx, appID, instance1ID)
-	if !strings.Contains(instanceDebug, "Blessing Store: Default blessings: test-principal/forapp/google naps") {
+	if !strings.Contains(instanceDebug, fmt.Sprintf("Blessing Store: Default blessings: %s/forapp/google naps", testutil.TestBlessing)) {
 		t.Fatalf("debug response doesn't contain expected info: %v", instanceDebug)
 	}