diff --git a/types/code_test.go b/types/code_test.go
new file mode 100644
index 000000000..d9032d3c5
--- /dev/null
+++ b/types/code_test.go
@@ -0,0 +1,12 @@
+package types
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestHumanCode(t *testing.T) {
+	assert.Equal(t, "Internal error", HumanCode(CodeType_InternalError))
+	assert.Equal(t, "Unknown code", HumanCode(-1))
+}