diff --git a/backend/tests/integration/test_friendship_routes.py b/backend/tests/integration/test_friendship_routes.py
new file mode 100644
index 0000000..64cfe01
--- /dev/null
+++ b/backend/tests/integration/test_friendship_routes.py
@@ -0,0 +1,364 @@
+from __future__ import annotations
+
+from datetime import datetime, timezone
+from typing import Callable
+from uuid import UUID
+
+from fastapi import HTTPException
+from fastapi.testclient import TestClient
+
+from app import app
+from core.auth.models import CurrentUser
+from v1.friendships.dependencies import get_friendship_service
+from v1.friendships.schemas import (
+    FriendRequestCreate,
+    FriendRequestResponse,
+    FriendResponse,
+    UserBasicInfo,
+)
+from v1.friendships.service import FriendshipService
+from v1.users.dependencies import get_current_user
+
+
+def _raise_unauthorized() -> CurrentUser:
+    raise HTTPException(status_code=401, detail="Unauthorized")
+
+
+class FakeFriendshipService(FriendshipService):
+    def __init__(self) -> None:
+        pass
+
+    async def send_request(self, request: FriendRequestCreate) -> FriendRequestResponse:
+        return FriendRequestResponse(
+            id=UUID("11111111-1111-1111-1111-111111111111"),
+            sender=UserBasicInfo(id="user-1", username="sender", avatar_url=None),
+            recipient=UserBasicInfo(id="user-2", username="recipient", avatar_url=None),
+            content=request.content,
+            status="pending",
+            created_at=datetime.now(timezone.utc),
+        )
+
+    async def accept_request(self, friendship_id: UUID) -> FriendRequestResponse:
+        return FriendRequestResponse(
+            id=friendship_id,
+            sender=UserBasicInfo(id="user-1", username="sender", avatar_url=None),
+            recipient=UserBasicInfo(id="user-2", username="recipient", avatar_url=None),
+            content="Hello!",
+            status="accepted",
+            created_at=datetime.now(timezone.utc),
+        )
+
+    async def decline_request(self, friendship_id: UUID) -> FriendRequestResponse:
+        return FriendRequestResponse(
+            id=friendship_id,
+            sender=UserBasicInfo(id="user-1", username="sender", avatar_url=None),
+            recipient=UserBasicInfo(id="user-2", username="recipient", avatar_url=None),
+            content="Hello!",
+            status="rejected",
+            created_at=datetime.now(timezone.utc),
+        )
+
+    async def cancel_request(self, friendship_id: UUID) -> FriendRequestResponse:
+        return FriendRequestResponse(
+            id=friendship_id,
+            sender=UserBasicInfo(id="user-1", username="sender", avatar_url=None),
+            recipient=UserBasicInfo(id="user-2", username="recipient", avatar_url=None),
+            content="Hello!",
+            status="canceled",
+            created_at=datetime.now(timezone.utc),
+        )
+
+    async def get_inbox(self) -> list[FriendRequestResponse]:
+        return [
+            FriendRequestResponse(
+                id=UUID("11111111-1111-1111-1111-111111111111"),
+                sender=UserBasicInfo(id="user-1", username="sender", avatar_url=None),
+                recipient=UserBasicInfo(
+                    id="user-2", username="recipient", avatar_url=None
+                ),
+                content="Hello!",
+                status="pending",
+                created_at=datetime.now(timezone.utc),
+            )
+        ]
+
+    async def get_outgoing_requests(self) -> list[FriendRequestResponse]:
+        return [
+            FriendRequestResponse(
+                id=UUID("22222222-2222-2222-2222-222222222222"),
+                sender=UserBasicInfo(id="user-1", username="sender", avatar_url=None),
+                recipient=UserBasicInfo(
+                    id="user-3", username="target", avatar_url=None
+                ),
+                content=None,
+                status="pending",
+                created_at=datetime.now(timezone.utc),
+            )
+        ]
+
+    async def get_friends_list(self) -> list[FriendResponse]:
+        return [
+            FriendResponse(
+                id=UUID("33333333-3333-3333-3333-333333333333"),
+                friend=UserBasicInfo(id="user-2", username="friend", avatar_url=None),
+                status="active",
+                created_at=datetime.now(timezone.utc),
+                accepted_at=datetime.now(timezone.utc),
+            )
+        ]
+
+    async def remove_friend(self, friend_id: UUID) -> FriendResponse:
+        return FriendResponse(
+            id=UUID("33333333-3333-3333-3333-333333333333"),
+            friend=UserBasicInfo(id=str(friend_id), username="friend", avatar_url=None),
+            status="active",
+            created_at=datetime.now(timezone.utc),
+            accepted_at=datetime.now(timezone.utc),
+        )
+
+
+def _override_friendship_service(
+    service: FriendshipService,
+) -> Callable[[], FriendshipService]:
+    def _get_service() -> FriendshipService:
+        return service
+
+    return _get_service
+
+
+def _get_fake_current_user() -> CurrentUser:
+    return CurrentUser(
+        id=UUID("00000000-0000-0000-0000-000000000001"),
+        email="test@example.com",
+    )
+
+
+class TestSendFriendRequest:
+    def test_send_friend_request_returns_201(self) -> None:
+        app.dependency_overrides[get_friendship_service] = _override_friendship_service(
+            FakeFriendshipService()
+        )
+        app.dependency_overrides[get_current_user] = _get_fake_current_user
+
+        client = TestClient(app)
+        try:
+            response = client.post(
+                "/api/v1/friends/requests",
+                json={
+                    "target_user_id": "22222222-2222-2222-2222-222222222222",
+                    "content": "Hello!",
+                },
+            )
+            assert response.status_code == 201
+            body = response.json()
+            assert body["status"] == "pending"
+            assert body["sender"]["username"] == "sender"
+            assert body["recipient"]["username"] == "recipient"
+        finally:
+            app.dependency_overrides = {}
+
+    def test_send_friend_request_missing_target_returns_422(self) -> None:
+        app.dependency_overrides[get_friendship_service] = _override_friendship_service(
+            FakeFriendshipService()
+        )
+        app.dependency_overrides[get_current_user] = _get_fake_current_user
+
+        client = TestClient(app)
+        try:
+            response = client.post("/api/v1/friends/requests", json={})
+            assert response.status_code == 422
+            assert response.headers["content-type"].startswith(
+                "application/problem+json"
+            )
+        finally:
+            app.dependency_overrides = {}
+
+    def test_send_friend_request_invalid_uuid_returns_422(self) -> None:
+        app.dependency_overrides[get_friendship_service] = _override_friendship_service(
+            FakeFriendshipService()
+        )
+        app.dependency_overrides[get_current_user] = _get_fake_current_user
+
+        client = TestClient(app)
+        try:
+            response = client.post(
+                "/api/v1/friends/requests",
+                json={"target_user_id": "invalid-uuid"},
+            )
+            assert response.status_code == 422
+            assert response.headers["content-type"].startswith(
+                "application/problem+json"
+            )
+        finally:
+            app.dependency_overrides = {}
+
+
+class TestGetInbox:
+    def test_get_inbox_returns_200(self) -> None:
+        app.dependency_overrides[get_friendship_service] = _override_friendship_service(
+            FakeFriendshipService()
+        )
+        app.dependency_overrides[get_current_user] = _get_fake_current_user
+
+        client = TestClient(app)
+        try:
+            response = client.get("/api/v1/friends/requests/inbox")
+            assert response.status_code == 200
+            body = response.json()
+            assert isinstance(body, list)
+            assert len(body) == 1
+            assert body[0]["status"] == "pending"
+        finally:
+            app.dependency_overrides = {}
+
+
+class TestGetOutgoingRequests:
+    def test_get_outgoing_requests_returns_200(self) -> None:
+        app.dependency_overrides[get_friendship_service] = _override_friendship_service(
+            FakeFriendshipService()
+        )
+        app.dependency_overrides[get_current_user] = _get_fake_current_user
+
+        client = TestClient(app)
+        try:
+            response = client.get("/api/v1/friends/requests/outgoing")
+            assert response.status_code == 200
+            body = response.json()
+            assert isinstance(body, list)
+            assert len(body) == 1
+            assert body[0]["status"] == "pending"
+        finally:
+            app.dependency_overrides = {}
+
+
+class TestAcceptFriendRequest:
+    def test_accept_friend_request_returns_200(self) -> None:
+        app.dependency_overrides[get_friendship_service] = _override_friendship_service(
+            FakeFriendshipService()
+        )
+        app.dependency_overrides[get_current_user] = _get_fake_current_user
+
+        client = TestClient(app)
+        try:
+            response = client.post(
+                "/api/v1/friends/requests/11111111-1111-1111-1111-111111111111/accept",
+                json={},
+            )
+            assert response.status_code == 200
+            body = response.json()
+            assert body["status"] == "accepted"
+        finally:
+            app.dependency_overrides = {}
+
+
+class TestDeclineFriendRequest:
+    def test_decline_friend_request_returns_200(self) -> None:
+        app.dependency_overrides[get_friendship_service] = _override_friendship_service(
+            FakeFriendshipService()
+        )
+        app.dependency_overrides[get_current_user] = _get_fake_current_user
+
+        client = TestClient(app)
+        try:
+            response = client.post(
+                "/api/v1/friends/requests/11111111-1111-1111-1111-111111111111/decline",
+                json={},
+            )
+            assert response.status_code == 200
+            body = response.json()
+            assert body["status"] == "rejected"
+        finally:
+            app.dependency_overrides = {}
+
+
+class TestCancelFriendRequest:
+    def test_cancel_friend_request_returns_204(self) -> None:
+        app.dependency_overrides[get_friendship_service] = _override_friendship_service(
+            FakeFriendshipService()
+        )
+        app.dependency_overrides[get_current_user] = _get_fake_current_user
+
+        client = TestClient(app)
+        try:
+            response = client.delete(
+                "/api/v1/friends/requests/11111111-1111-1111-1111-111111111111"
+            )
+            assert response.status_code == 204
+            assert response.content == b""
+        finally:
+            app.dependency_overrides = {}
+
+
+class TestGetFriendsList:
+    def test_get_friends_list_returns_200(self) -> None:
+        app.dependency_overrides[get_friendship_service] = _override_friendship_service(
+            FakeFriendshipService()
+        )
+        app.dependency_overrides[get_current_user] = _get_fake_current_user
+
+        client = TestClient(app)
+        try:
+            response = client.get("/api/v1/friends")
+            assert response.status_code == 200
+            body = response.json()
+            assert isinstance(body, list)
+            assert len(body) == 1
+            assert body[0]["status"] == "active"
+            assert body[0]["friend"]["username"] == "friend"
+        finally:
+            app.dependency_overrides = {}
+
+
+class TestRemoveFriend:
+    def test_remove_friend_returns_204(self) -> None:
+        app.dependency_overrides[get_friendship_service] = _override_friendship_service(
+            FakeFriendshipService()
+        )
+        app.dependency_overrides[get_current_user] = _get_fake_current_user
+
+        client = TestClient(app)
+        try:
+            response = client.delete(
+                "/api/v1/friends/33333333-3333-3333-3333-333333333333"
+            )
+            assert response.status_code == 204
+            assert response.content == b""
+        finally:
+            app.dependency_overrides = {}
+
+
+class TestFriendshipRequiresAuth:
+    def test_send_request_without_auth_returns_401(self) -> None:
+        app.dependency_overrides[get_current_user] = _raise_unauthorized
+
+        client = TestClient(app)
+        try:
+            response = client.post(
+                "/api/v1/friends/requests",
+                json={
+                    "target_user_id": "22222222-2222-2222-2222-222222222222",
+                },
+            )
+            assert response.status_code == 401
+        finally:
+            app.dependency_overrides = {}
+
+    def test_get_inbox_without_auth_returns_401(self) -> None:
+        app.dependency_overrides[get_current_user] = _raise_unauthorized
+
+        client = TestClient(app)
+        try:
+            response = client.get("/api/v1/friends/requests/inbox")
+            assert response.status_code == 401
+        finally:
+            app.dependency_overrides = {}
+
+    def test_get_friends_without_auth_returns_401(self) -> None:
+        app.dependency_overrides[get_current_user] = _raise_unauthorized
+
+        client = TestClient(app)
+        try:
+            response = client.get("/api/v1/friends")
+            assert response.status_code == 401
+        finally:
+            app.dependency_overrides = {}