Test coverage nima ne?

Question

IT Interview Practice · Accepted Answer

**Test coverage** yana auna nawa jiya code **ana aiwatarwa ta hanyar gwaje** — galibi a fiye kashi (misali 80% coverage). Shi matsayi mai amfani ne don nemo code da bai gwajuwa ba, amma yana da mahimmanci ganinsu iyakoki: coverage mai girma bai bada garantin bukatun gwaje ba.

## Abin da coverage yake auna

```text
TEST COVERAGE = the % of code exercised by the test suite:
  LINE coverage → % of code lines executed by tests
  BRANCH coverage → % of branches (if/else paths) taken
  FUNCTION coverage → % of functions called
  STATEMENT coverage → % of statements executed
→ Coverage tools instrument the code and report what tests do/don't exercise.
```

## Me yake sa coverage useful

```text
✓ FINDS UNTESTED code — low coverage areas reveal what lacks tests (a gap finder)
✓ A measurable quality signal; track it over time; many teams set a target (e.g. ≥80%)
✓ Highlights branches/paths/error cases that tests miss
```

## Iyakoki (muhimmanci!)

```text
⚠️ HIGH COVERAGE ≠ GOOD TESTS:
  → coverage shows code was EXECUTED, NOT that behavior was correctly VERIFIED
  → you can execute code with NO meaningful assertions → 100% coverage, tests verify nothing
  → 100% coverage can still miss bugs (untested input combinations, logic errors)
⚠️ Chasing a coverage NUMBER → writing low-value tests just to hit the target
→ Coverage is a USEFUL guide (find gaps), NOT a guarantee of quality. Use it wisely;
  focus on testing important behavior well, not just hitting a percentage.
```

## Me yake sa shi muhimmanci

Sanin test coverage — ciki har da iyakokinsa — yana da daraja domin shi **matsayi da ake amfani da shi" wanda ya zama da mahimmanci lokacin da aka fahimta daidai amma yana kwazo lokacin da aka yi masa illa, don haka yana da mahimmanci ilimin aiki.

Coverage yana auna **nawa jiya code da hanyar gwaje suka aiwatarwa** (a fiye kashi, ta hanyar laini, reshe, aiki, ko bayyananniyar aiwatarwa), sanin shi yana da amfani domin **nemo code ba a gwajuwa** (nuna abubuwan ba a gwajuwa — hanyar mahimman gano abin da ake bukatar gwajuwa), samar da alama mai auna mutane ta hanyar uku na iya bin bayyananniya, da kuma nura reshe da lokuta rashin godiya.

Tawaje da jama'a suna amfani da coverage a matsayin matsayi na mutane ta hanyar uku tare da manufa.

Ko da haka, sanin **iyakoki yana da muhimmanci sosai**: **coverage mai girma ba sama da bukatun gwaje masu kyau** — coverage yana nuni cewa code ya aiwatarwa, ba cewa halinsa a **tabbata daidai** ba, don haka kuna iya samun coverage mai girma (har da 100%) tare da gwaje mara ma'ana (aiwatarwar code ba tare da ingantacciyar tunanin ba ba wai tabbatar da wani abu ba), da coverage cikakke zai iya rasa kudu (maki da ba a gwajuwa na haɗa, kuskure na logik).

haɗarin **bin lamba ta coverage** (rubuta gwaje mara auki ne kawai don samun lambar), shi tsari da ba daidai ba.

Sanin cewa **coverage alaturin niyya ne don nemo abubuwan da suka rasa, ba garantin abin da ya kyau** — da cewa juyau ta kamata ya kasance akan bada gwaje makamai da kyau maimakon samun kashi — yana nuni hakim cewa sanin ba daidai wanda yake guje jiya sani na rubutun gwaje ba jiya kasar.

Domin coverage shi matsayi da ake amfani da shi sosai wanda shi tokici mai aiki (nemo code ba a gwajuwa) amma a yau da can ana sani da shi musamman da aka yi masa illa (ana amfani da shi azaman garantin abin kyau ko niyya da za a bida), sanin duka arziki da mahimmancin iyakoki yana ba da damar amfani da shi halin da ya kamata, sanin test coverage yana da mahimmanci, sanin ilimin aiki — matsayi mai auna don fahimta daidai, inda fahimtar iyakoki (coverage ≠ abin kyau) yana daidai mahimmanci da matsayi kansa, yana nuni hakim na jiya abubuwa.

Abin da coverage yake auna

Me yake sa coverage useful

Iyakoki (muhimmanci!)

Me yake sa shi muhimmanci

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