test: 补充知识处理、检索与 Agent 回归用例

覆盖切块、向量检索、工具调用和历史预算；模型相关用例使用桩。

backend/tests/repo/test_group_repo.py

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+"""
+Copyright 2024-2026 ChatterMate
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+
+import pytest
+from app.repositories.group import GroupRepository
+from app.models.user import UserGroup, User
+from uuid import uuid4, UUID
+
+@pytest.fixture
+def group_repo(db):
+    return GroupRepository(db)
+
+@pytest.fixture
+def test_group(db, test_organization_id):
+    """Create a test group with users"""
+    group = UserGroup(
+        id=uuid4(),
+        name="Test Group",
+        description="A test group",
+        organization_id=test_organization_id
+    )
+    db.add(group)
+    
+    # Create test users
+    users = []
+    for i in range(3):
+        user = User(
+            id=uuid4(),
+            email=f"user{i}@test.com",
+            full_name=f"Test User {i}",
+            hashed_password="dummy_hash",
+            is_active=True,
+            organization_id=test_organization_id
+        )
+        users.append(user)
+        db.add(user)
+    
+    # Associate users with the group
+    group.users.extend(users)
+    db.commit()
+    db.refresh(group)
+    return group
+
+def test_get_group_with_users(group_repo, test_group):
+    """Test retrieving a group with its associated users"""
+    # Get the group with users
+    group = group_repo.get_group_with_users(test_group.id)
+    
+    # Verify group data
+    assert group is not None
+    assert group.id == test_group.id
+    assert group.name == "Test Group"
+    assert group.description == "A test group"
+    
+    # Verify associated users
+    assert len(group.users) == 3
+    for i, user in enumerate(group.users):
+        assert user.email == f"user{i}@test.com"
+        assert user.full_name == f"Test User {i}"
+        assert user.is_active is True
+
+def test_get_nonexistent_group(group_repo):
+    """Test retrieving a group that doesn't exist"""
+    group = group_repo.get_group_with_users(uuid4())
+    assert group is None