优化

internal/service/department_test.go

@@ -0,0 +1,16 @@
+package service
+
+import (
+	"testing"
+
+	"kra/internal/biz"
+)
+
+func TestDepartmentResponsePreservesNilAndEmptyChildren(t *testing.T) {
+	if got := departmentResponse(&biz.Department{}).Children; got != nil {
+		t.Fatalf("single/search department children = %#v, want nil", got)
+	}
+	if got := departmentResponse(&biz.Department{Children: []*biz.Department{}}).Children; got == nil || len(got) != 0 {
+		t.Fatalf("tree leaf children = %#v, want empty slice", got)
+	}
+}