1 files changed, 21 insertions, 0 deletions
diff --git a/control/controlknobs/controlknobs_test.go b/control/controlknobs/controlknobs_test.go
new file mode 100644
index 000000000..266a4708d
--- /dev/null
+++ b/control/controlknobs/controlknobs_test.go
@@ -0,0 +1,21 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+package controlknobs
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestAsDebugJSON(t *testing.T) {
+	var nilPtr *Knobs
+	if got := nilPtr.AsDebugJSON(); got != nil {
+		t.Errorf("AsDebugJSON(nil) = %v; want nil", got)
+	}
+	k := new(Knobs)
+	got := k.AsDebugJSON()
+	if want := reflect.TypeOf(Knobs{}).NumField(); len(got) != want {
+		t.Errorf("AsDebugJSON map has %d fields; want %v", len(got), want)
+	}
+}