আপনি লিগেসি কোডে কীভাবে টেস্ট যোগ করেন?

Legacy code is often: untested, tightly coupled, hard to understand, risky to change:
  → no tests → changing it is dangerous (you can't tell if you broke something)
  → hard to test → dependencies are tangled (can't isolate units); not designed for testing
→ a chicken-and-egg problem: to change safely you need tests, but it's hard to test.