feat: implement Instagram clone SocialPhoto API

- FastAPI backend with SQLite database
- JWT authentication (register, login)
- User profiles with follow/unfollow
- Posts with image upload and likes/dislikes
- Comments with likes
- Global and personalized feed
- Comprehensive pytest test suite (37 tests)

TASK-ID: 758f4029-702

tests/test_auth.py

@@ -0,0 +1,158 @@
+"""Tests for authentication routes."""
+import pytest
+from fastapi.testclient import TestClient
+
+
+def test_register_success(client: TestClient):
+    """Test successful user registration."""
+    response = client.post(
+        "/auth/register",
+        json={
+            "username": "newuser",
+            "email": "newuser@example.com",
+            "password": "password123",
+        },
+    )
+    assert response.status_code == 201
+    data = response.json()
+    assert "access_token" in data
+    assert data["token_type"] == "bearer"
+
+
+def test_register_duplicate_username(client: TestClient):
+    """Test registration with duplicate username."""
+    # First registration
+    client.post(
+        "/auth/register",
+        json={
+            "username": "duplicate",
+            "email": "first@example.com",
+            "password": "password123",
+        },
+    )
+
+    # Second registration with same username
+    response = client.post(
+        "/auth/register",
+        json={
+            "username": "duplicate",
+            "email": "second@example.com",
+            "password": "password123",
+        },
+    )
+    assert response.status_code == 400
+    assert "Username already registered" in response.json()["detail"]
+
+
+def test_register_duplicate_email(client: TestClient):
+    """Test registration with duplicate email."""
+    # First registration
+    client.post(
+        "/auth/register",
+        json={
+            "username": "firstuser",
+            "email": "same@example.com",
+            "password": "password123",
+        },
+    )
+
+    # Second registration with same email
+    response = client.post(
+        "/auth/register",
+        json={
+            "username": "seconduser",
+            "email": "same@example.com",
+            "password": "password123",
+        },
+    )
+    assert response.status_code == 400
+    assert "Email already registered" in response.json()["detail"]
+
+
+def test_register_invalid_email(client: TestClient):
+    """Test registration with invalid email format."""
+    response = client.post(
+        "/auth/register",
+        json={
+            "username": "validuser",
+            "email": "not-an-email",
+            "password": "password123",
+        },
+    )
+    assert response.status_code == 422  # Validation error
+
+
+def test_register_short_password(client: TestClient):
+    """Test registration with too short password."""
+    response = client.post(
+        "/auth/register",
+        json={
+            "username": "validuser",
+            "email": "valid@example.com",
+            "password": "12345",
+        },
+    )
+    assert response.status_code == 422  # Validation error
+
+
+def test_login_success(client: TestClient):
+    """Test successful login."""
+    # Register first
+    client.post(
+        "/auth/register",
+        json={
+            "username": "loginuser",
+            "email": "login@example.com",
+            "password": "password123",
+        },
+    )
+
+    # Login
+    response = client.post(
+        "/auth/login",
+        json={
+            "username": "loginuser",
+            "password": "password123",
+        },
+    )
+    assert response.status_code == 200
+    data = response.json()
+    assert "access_token" in data
+    assert data["token_type"] == "bearer"
+
+
+def test_login_wrong_password(client: TestClient):
+    """Test login with wrong password."""
+    # Register first
+    client.post(
+        "/auth/register",
+        json={
+            "username": "testuser",
+            "email": "test@example.com",
+            "password": "correctpassword",
+        },
+    )
+
+    # Login with wrong password
+    response = client.post(
+        "/auth/login",
+        json={
+            "username": "testuser",
+            "password": "wrongpassword",
+        },
+    )
+    assert response.status_code == 401
+    assert "Incorrect username or password" in response.json()["detail"]
+
+
+def test_login_nonexistent_user(client: TestClient):
+    """Test login with nonexistent username."""
+    response = client.post(
+        "/auth/login",
+        json={
+            "username": "nonexistent",
+            "password": "password123",
+        },
+    )
+    assert response.status_code == 401
+    assert "Incorrect username or password" in response.json()["detail"]