Yaya za ka ƙara jajiya ga kodeks na tsohuwa?

Question

Accepted Answer

**Kodeks na tsohuwa** (sau da yawa ba shi da jajiya, kodeks mai wahala ǹ canja) yana da ƙalubale a jajiye — ƙila yana da haɗaɗɗiyar abin dogara kuma ba shi da jajiya. Ƙarin jajiya mai aminci ya kunshi fasahohin kamar **jajiya na halayyar gida**, **seams** don rushe dogara, da ci gaba ɗan karatu, wanda ke bu da m karatu mabadowa.

## Matsalar kodeks na tsohuwa

```text
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.
```

## Jajiya na halayyar gida (damre aiki na yanzu)

```text
CHARACTERIZATION (golden master) tests → capture the code's CURRENT behavior as-is
  (even if you don't fully understand it / it has bugs):
  → write tests asserting what it ACTUALLY does now → a SAFETY NET
  → then you can refactor/change with confidence that behavior is preserved
→ Don't assert what it SHOULD do — assert what it DOES, to protect against regressions.
```

## Rushe dogara (seams)

```text
To isolate hard-to-test code, find/create SEAMS (places to substitute dependencies):
  → extract dependencies behind interfaces; inject them; use the smallest safe refactors
    to make code testable (Michael Feathers' techniques)
  → carefully break dependencies so you can get the code under test, then test, then refactor
```

## Hanyar ci gaba ɗan karatu

```text
✓ Add tests AROUND code BEFORE changing it (a safety net for the change)
✓ Focus on areas you're CHANGING / high-risk / high-value (not the whole codebase at once)
✓ Improve incrementally — leave code a bit better each time (the "boy scout rule")
✓ Use characterization tests to capture behavior, then refactor toward testability
```

## Dalilin da aka tsaya

Jiwon karewa yadda za ka ƙara jajiya ga kodeks na tsohuwa shine ilimin da aka sani a matakin da yawa domin **yawancin aiki na gida ya kunshi kodeks na jiya, sau da yawa ba shi da jajiya**, kuma inganta shi da aminci shine matsala ta gida da mahimmanci, don haka yana da mahimmanci a takaice.

Kodeks na tsohuwa (ba shi da jajiya, haɗaɗɗi mai tight coupling, kodeks mai wahala ɗ ƙara jajiya) yana gabatarwa da matsalai na ainihi na "kaji-kuma-kaji": don canja shi da aminci kana bukatar jajiya, amma yana da wahala ǹ jajiye (haɗaɗɗiyar abin dogara, ba shi da tsarawa don jajiya) — kuma canja kodeks ba tare da jajiya ba yana haɗari domin ba za ka iya sanin idan ka rushe wani abu.

Jiwon karewa fasahohin da za a yi don daidaita haka shine ilimin aiki mai amfani. **Jajiya na halayyar gida** (tarewa halayyar kodeks na *yanzu* kamar yadda yake, damre abin da sai sai ya yi maimakon abin da ya kamata — ko da ba ku cikakke fahimta ba) suna ba da **karkatu na jiya** wanda ke ba ka ikon gyara jajiya kuma canja tare da aminci cewa halayyar jiya an adina — fasahin mahimmanci don aiki tare da kodeks da ba ka cikakke fahimta ba.

Jiwon karewa **rushe dogara ta hanyar seams** (nemo ko haɗa wurare don maye gurbin dogara, amfani da ƙarami da aminci mabadowa don baba da haɗaɗɗi kodeks wanda ya zama mai jajiya — fasahohin daga aikin Michael Feathers a kodeks na tsohuwa) shine ainihi don samu kodeks mai wahala ǹ jajiye a jajiya.

Jiwon karewa **hanyar ci gaba ɗan karatu** — ƙarin jajiya kewaye da kodeks kafin canja shi (karkatu na jiya don canja), mai tunani a ungulun kodeks da ake canja ko matakin haɗari/mahimmanci (ba duk gida a jiya ba), kuma inganta a karatu ɗan karatu (moon boy scout rule) — yana nuna hanyar ainihi, gaskiya yadda za a inganta tsohon tsarin aiki.

Domin yawancin aiki na gida ya kunshi kodeks na tsohuwa, sau da yawa ba shi da jajiya wanda dole a canja shi da aminci (matsalar gida da ƙalubale), kuma domin fahimtar fasahohin (jajiya na halayyar gida don karkatu na jiya, seams don rushe dogara, ci gaba ɗan karatu) yana ba da ikon yin haka, fahimtar yadda za ka ƙara jajiya ga kodeks na tsohuwa shine ilimin matakin da yawa — aiki mai amfani don gaskiyar gida na aiki tare da kodeks na tsohuwa ba tare da jajiya ba, wanda ke nuna karni da fasahohin da aka bukatar don inganta tsohon tsarin aiki da aminci, mahimmanci mai mahimmanci ga injiniyoyin da aka tsaya da yawa wajen ka buƙata baba da kodeks ba tare da jajiya da aminci ba.