Add tests for trace registry

cmd/census.go

@@ -5,6 +5,7 @@ import (
 	"net/http"
 	"os"
 
+	"github.com/cpuguy83/strongerrors"
 	"github.com/pkg/errors"
 	"github.com/virtual-kubelet/virtual-kubelet/log"
 	"go.opencensus.io/trace"
@@ -42,7 +43,7 @@ func RegisterTracingExporter(name string, f TracingExporterInitFunc) {
 func GetTracingExporter(name string, opts TracingExporterOptions) (trace.Exporter, error) {
 	f, ok := tracingExporters[name]
 	if !ok {
-		return nil, errors.Errorf("tracing exporter %q not found", name)
+		return nil, strongerrors.NotFound(errors.Errorf("tracing exporter %q not found", name))
 	}
 	return f(opts)
 }