Yadda kake gwaji da aplikashinoni na FastAPI?

Question

Accepted Answer

FastAPI yana da babbar iko ga gwaji saboda **`TestClient`** tasa (wanda aka ginawa will Starlette/httpx) da **tsarin toshe abubuwan da ake bukatarwa** (dependency injection), wanda ke sa damewa na abubuwan da ake bukatarwa ba komai. Gwajin gida yawanci suna amfani da `pytest` da `TestClient` don aiko da bukatun zuwa app ba tare da jari mai aiki ba.

## Gwajin tushe gida ta kasua TestClient

```python
from fastapi.testclient import TestClient
from main import app

client = TestClient(app)

def test_read_item():
    response = client.get("/items/5")            # send a request to the app in-process
    assert response.status_code == 200
    assert response.json() == {"item_id": 5}

def test_create_item():
    response = client.post("/items", json={"name": "Phone", "price": 999})
    assert response.status_code == 201
    assert response.json()["name"] == "Phone"

def test_validation_error():
    response = client.post("/items", json={"name": "Phone"})   # missing price
    assert response.status_code == 422                          # FastAPI validates automatically
```

`TestClient` yana aiko da tunani na ainihi zuwa app tiyaga cikin aiki (ba jari da ake bukata), don haka kana gwaji cikakken jadwali — jigyara, bada daidai, zayyana — da kwatanta kan nau'i-nau'in jidir da sakamakon JSON.

## Tsoge abubuwan da ake bukatarwa (makullin tsohuwar gwajin)

```python
# override a dependency with a mock/test version — no real database needed
def override_get_db():
    return test_db_session

app.dependency_overrides[get_db] = override_get_db   # swap the real dependency

def test_with_test_db():
    response = client.get("/users")
    # uses the test database via the override
    app.dependency_overrides.clear()                 # reset after
```

FastAPI's `dependency_overrides` yana ba da dami don **saita kowane abin da ake bukatarwa** (yaduwar zangon bayanai, girki, sabis na waje) tare da gwaji na doble — tushen sauri, ware-warewa na gwaji, wanda FastAPI jirgin saurinsa ya sayyade.

## Gwajin garin da ke karantia

```python
def test_protected():
    # override the auth dependency to simulate a logged-in user
    app.dependency_overrides[get_current_user] = lambda: fake_user
    response = client.get("/me")
    assert response.status_code == 200
```

## Dabarar gwaji

```text
✓ Use a TEST database (separate, or transactions rolled back per test)
✓ Override dependencies (DB, auth, external APIs) for isolation
✓ Test: status codes, response shapes, validation (422s), auth/permissions, edge cases
✓ For async-specific code, use httpx.AsyncClient / pytest-asyncio
✓ Tools: pytest, factory libraries for test data, coverage.py
```

## Me ya sa ya matuwa

Gwaji yana da mahimmanci don aplikashinoni da aka kwaranta, kuma FastAPI yana da saurin gwaji — fahimtar yadda za a gwaji shi yana muhimmi saboda dori na kalidad da saboda tsarin shine *saniye* don gwaji.

**`TestClient`** yana sauyar da sauki wajen gwaji cikakken rashin niyya/sakamakon jadwali cikin aiki (babu jari da ake bukata), yana tabbatar da jigyara, tabbatar, zayyana, da sakamakon kamar yadda abokan jari za su gaske.

Bakun a kan gida shine **tsoge abubuwan da ake bukatarwa**: saboda FastAPI yana amfani da toshe abubuwan, kana iya saita kowane abin da ake bukatarwa — yaduwar zangon bayanai, girki, sabis na waje — tare da bayyani na gwaji ta hanyar `app.dependency_overrides`, wanda ke bayar da gwaji mai sauri, ware-warewa ba tare da ainihin kasua (wannan gwajin iko shine babbar amfani na toshe abubuwan).

Sanin yadda za a yi amfani da TestClient, tsoge abubuwan don ware-warewa (gwaji zangon bayanai, girki/sabis da aka yi alwa), gwajin garin da ke karantia, da tsara dabarar gwaji mai ma'ana (nau'i-nau'in jidir, fasali na sakamakon, bada daidai, girki, lokaci na gida) yana da mahimmanci sanin manyan matukun FastAPI, saboda gina sabis na aiki da aka kwaranta.

Gwajin da aka koyi ana kama jajiya na saka-saka da ba da iko na gida yadda za a saita, kuma kayan gwaji na FastAPI suna sauyar da gwaji mai cikakke, wanda ya sayyade wannan gida a yau-yau, muhimmiyar, na aiki.