diff --git a/backend/app/services/oasis_models.py b/backend/app/services/oasis_models.py
new file mode 100644
index 00000000..46bc2f5f
--- /dev/null
+++ b/backend/app/services/oasis_models.py
@@ -0,0 +1,181 @@
+"""
+OASIS 数据模型
+
+包含 OasisAgentProfile 数据类和相关的辅助函数。
+这些组件不依赖 Flask，可以独立使用。
+"""
+
+import random
+from dataclasses import dataclass, field
+from datetime import datetime
+from typing import Dict, Any, List, Optional
+
+
+# Entity type classification constants
+INDIVIDUAL_ENTITY_TYPES = [
+    "student", "alumni", "professor", "person", "publicfigure",
+    "expert", "faculty", "official", "journalist", "activist"
+]
+
+GROUP_ENTITY_TYPES = [
+    "university", "governmentagency", "organization", "ngo",
+    "mediaoutlet", "company", "institution", "group", "community"
+]
+
+
+@dataclass
+class OasisAgentProfile:
+    """OASIS Agent Profile数据结构"""
+    # 通用字段
+    user_id: int
+    user_name: str
+    name: str
+    bio: str
+    persona: str
+
+    # 可选字段 - Reddit风格
+    karma: int = 1000
+
+    # 可选字段 - Twitter风格
+    friend_count: int = 100
+    follower_count: int = 150
+    statuses_count: int = 500
+
+    # 额外人设信息
+    age: Optional[int] = None
+    gender: Optional[str] = None
+    mbti: Optional[str] = None
+    country: Optional[str] = None
+    profession: Optional[str] = None
+    interested_topics: List[str] = field(default_factory=list)
+
+    # 来源实体信息
+    source_entity_uuid: Optional[str] = None
+    source_entity_type: Optional[str] = None
+
+    created_at: str = field(default_factory=lambda: datetime.now().strftime("%Y-%m-%d"))
+
+    def to_reddit_format(self) -> Dict[str, Any]:
+        """转换为Reddit平台格式"""
+        profile = {
+            "user_id": self.user_id,
+            "username": self.user_name,  # OASIS 库要求字段名为 username（无下划线）
+            "name": self.name,
+            "bio": self.bio,
+            "persona": self.persona,
+            "karma": self.karma,
+            "created_at": self.created_at,
+        }
+
+        # 添加额外人设信息（如果有）
+        if self.age:
+            profile["age"] = self.age
+        if self.gender:
+            profile["gender"] = self.gender
+        if self.mbti:
+            profile["mbti"] = self.mbti
+        if self.country:
+            profile["country"] = self.country
+        if self.profession:
+            profile["profession"] = self.profession
+        if self.interested_topics:
+            profile["interested_topics"] = self.interested_topics
+
+        return profile
+
+    def to_twitter_format(self) -> Dict[str, Any]:
+        """转换为Twitter平台格式"""
+        profile = {
+            "user_id": self.user_id,
+            "username": self.user_name,  # OASIS 库要求字段名为 username（无下划线）
+            "name": self.name,
+            "bio": self.bio,
+            "persona": self.persona,
+            "friend_count": self.friend_count,
+            "follower_count": self.follower_count,
+            "statuses_count": self.statuses_count,
+            "created_at": self.created_at,
+        }
+
+        # 添加额外人设信息
+        if self.age:
+            profile["age"] = self.age
+        if self.gender:
+            profile["gender"] = self.gender
+        if self.mbti:
+            profile["mbti"] = self.mbti
+        if self.country:
+            profile["country"] = self.country
+        if self.profession:
+            profile["profession"] = self.profession
+        if self.interested_topics:
+            profile["interested_topics"] = self.interested_topics
+
+        return profile
+
+    def to_dict(self) -> Dict[str, Any]:
+        """转换为完整字典格式"""
+        return {
+            "user_id": self.user_id,
+            "user_name": self.user_name,
+            "name": self.name,
+            "bio": self.bio,
+            "persona": self.persona,
+            "karma": self.karma,
+            "friend_count": self.friend_count,
+            "follower_count": self.follower_count,
+            "statuses_count": self.statuses_count,
+            "age": self.age,
+            "gender": self.gender,
+            "mbti": self.mbti,
+            "country": self.country,
+            "profession": self.profession,
+            "interested_topics": self.interested_topics,
+            "source_entity_uuid": self.source_entity_uuid,
+            "source_entity_type": self.source_entity_type,
+            "created_at": self.created_at,
+        }
+
+
+def _generate_username(name: str) -> str:
+    """生成用户名"""
+    username = name.lower().replace(" ", "_")
+    username = ''.join(c for c in username if c.isalnum() or c == '_')
+    suffix = random.randint(100, 999)
+    return f"{username}_{suffix}"
+
+
+def _normalize_gender(gender: Optional[str]) -> str:
+    """
+    标准化gender字段为OASIS要求的英文格式
+
+    OASIS要求: male, female, other
+    """
+    if not gender:
+        return "other"
+
+    gender_lower = gender.lower().strip()
+
+    # 中文映射
+    gender_map = {
+        "男": "male",
+        "女": "female",
+        "机构": "other",
+        "其他": "other",
+        # 英文已有
+        "male": "male",
+        "female": "female",
+        "other": "other",
+    }
+
+    return gender_map.get(gender_lower, "other")
+
+
+def _is_individual_entity(entity_type: str) -> bool:
+    """判断是否是个人类型实体"""
+    return entity_type.lower() in INDIVIDUAL_ENTITY_TYPES
+
+
+def _is_group_entity(entity_type: str) -> bool:
+    """判断是否是群体/机构类型实体"""
+    return entity_type.lower() in GROUP_ENTITY_TYPES
\ No newline at end of file
diff --git a/backend/app/services/oasis_profile_generator.py b/backend/app/services/oasis_profile_generator.py
index 7704a627..49e667d6 100644
--- a/backend/app/services/oasis_profile_generator.py
+++ b/backend/app/services/oasis_profile_generator.py
@@ -12,8 +12,6 @@ import json
 import random
 import time
 from typing import Dict, Any, List, Optional
-from dataclasses import dataclass, field
-from datetime import datetime
 
 from openai import OpenAI
 from zep_cloud.client import Zep
@@ -22,124 +20,11 @@ from ..config import Config
 from ..utils.logger import get_logger
 from ..utils.locale import get_language_instruction, get_locale, set_locale, t
 from .zep_entity_reader import EntityNode, ZepEntityReader
+from .oasis_models import OasisAgentProfile
 
 logger = get_logger('mirofish.oasis_profile')
 
 
-@dataclass
-class OasisAgentProfile:
-    """OASIS Agent Profile数据结构"""
-    # 通用字段
-    user_id: int
-    user_name: str
-    name: str
-    bio: str
-    persona: str
-    
-    # 可选字段 - Reddit风格
-    karma: int = 1000
-    
-    # 可选字段 - Twitter风格
-    friend_count: int = 100
-    follower_count: int = 150
-    statuses_count: int = 500
-    
-    # 额外人设信息
-    age: Optional[int] = None
-    gender: Optional[str] = None
-    mbti: Optional[str] = None
-    country: Optional[str] = None
-    profession: Optional[str] = None
-    interested_topics: List[str] = field(default_factory=list)
-    
-    # 来源实体信息
-    source_entity_uuid: Optional[str] = None
-    source_entity_type: Optional[str] = None
-    
-    created_at: str = field(default_factory=lambda: datetime.now().strftime("%Y-%m-%d"))
-    
-    def to_reddit_format(self) -> Dict[str, Any]:
-        """转换为Reddit平台格式"""
-        profile = {
-            "user_id": self.user_id,
-            "username": self.user_name,  # OASIS 库要求字段名为 username（无下划线）
-            "name": self.name,
-            "bio": self.bio,
-            "persona": self.persona,
-            "karma": self.karma,
-            "created_at": self.created_at,
-        }
-        
-        # 添加额外人设信息（如果有）
-        if self.age:
-            profile["age"] = self.age
-        if self.gender:
-            profile["gender"] = self.gender
-        if self.mbti:
-            profile["mbti"] = self.mbti
-        if self.country:
-            profile["country"] = self.country
-        if self.profession:
-            profile["profession"] = self.profession
-        if self.interested_topics:
-            profile["interested_topics"] = self.interested_topics
-        
-        return profile
-    
-    def to_twitter_format(self) -> Dict[str, Any]:
-        """转换为Twitter平台格式"""
-        profile = {
-            "user_id": self.user_id,
-            "username": self.user_name,  # OASIS 库要求字段名为 username（无下划线）
-            "name": self.name,
-            "bio": self.bio,
-            "persona": self.persona,
-            "friend_count": self.friend_count,
-            "follower_count": self.follower_count,
-            "statuses_count": self.statuses_count,
-            "created_at": self.created_at,
-        }
-        
-        # 添加额外人设信息
-        if self.age:
-            profile["age"] = self.age
-        if self.gender:
-            profile["gender"] = self.gender
-        if self.mbti:
-            profile["mbti"] = self.mbti
-        if self.country:
-            profile["country"] = self.country
-        if self.profession:
-            profile["profession"] = self.profession
-        if self.interested_topics:
-            profile["interested_topics"] = self.interested_topics
-        
-        return profile
-    
-    def to_dict(self) -> Dict[str, Any]:
-        """转换为完整字典格式"""
-        return {
-            "user_id": self.user_id,
-            "user_name": self.user_name,
-            "name": self.name,
-            "bio": self.bio,
-            "persona": self.persona,
-            "karma": self.karma,
-            "friend_count": self.friend_count,
-            "follower_count": self.follower_count,
-            "statuses_count": self.statuses_count,
-            "age": self.age,
-            "gender": self.gender,
-            "mbti": self.mbti,
-            "country": self.country,
-            "profession": self.profession,
-            "interested_topics": self.interested_topics,
-            "source_entity_uuid": self.source_entity_uuid,
-            "source_entity_type": self.source_entity_type,
-            "created_at": self.created_at,
-        }
-
-
 class OasisProfileGenerator:
     """
     OASIS Profile生成器
diff --git a/backend/pytest.ini b/backend/pytest.ini
new file mode 100644
index 00000000..eb533896
--- /dev/null
+++ b/backend/pytest.ini
@@ -0,0 +1,9 @@
+[pytest]
+testpaths = tests
+python_files = test_*.py
+python_classes = Test*
+python_functions = test_*
+addopts = -v --tb=short
+filterwarnings =
+    ignore::DeprecationWarning
+    ignore::PendingDeprecationWarning
\ No newline at end of file
diff --git a/backend/tests/__init__.py b/backend/tests/__init__.py
new file mode 100644
index 00000000..d23df37f
--- /dev/null
+++ b/backend/tests/__init__.py
@@ -0,0 +1 @@
+# Backend tests package
\ No newline at end of file
diff --git a/backend/tests/conftest.py b/backend/tests/conftest.py
new file mode 100644
index 00000000..a18eeda8
--- /dev/null
+++ b/backend/tests/conftest.py
@@ -0,0 +1,52 @@
+"""
+Pytest configuration and shared fixtures for backend tests.
+
+This module provides fixtures that allow testing of modules that normally
+require Flask initialization, by mocking the necessary dependencies.
+"""
+
+import sys
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+
+@pytest.fixture(scope="session", autouse=True)
+def mock_external_dependencies():
+    """
+    Mock external dependencies (Flask, OpenAI, Zep) to allow testing
+    without initializing the full Flask app or requiring API keys.
+    """
+    mock_logger = MagicMock()
+    mock_locale = MagicMock()
+    mock_locale.get_locale.return_value = 'zh'
+    mock_locale.set_locale.return_value = None
+    mock_locale.get_language_instruction.return_value = 'Please answer in English.'
+    mock_locale.t.return_value = 'test'
+
+    mock_config = MagicMock()
+    mock_config.LLM_API_KEY = None
+    mock_config.LLM_BASE_URL = None
+    mock_config.LLM_MODEL_NAME = None
+    mock_config.ZEP_API_KEY = None
+
+    # Clear any previously imported app modules
+    for mod_name in list(sys.modules.keys()):
+        if mod_name.startswith('app.'):
+            del sys.modules[mod_name]
+
+    with patch.dict('sys.modules', {
+        'flask': MagicMock(),
+        'flask_cors': MagicMock(),
+        'openai': MagicMock(),
+        'zep_cloud': MagicMock(),
+        'zep_cloud.client': MagicMock(),
+        'app': MagicMock(),
+        'app.config': mock_config,
+        'app.utils': MagicMock(),
+        'app.utils.logger': mock_logger,
+        'app.utils.locale': mock_locale,
+        'app.services.zep_entity_reader': MagicMock(),
+    }):
+        yield
\ No newline at end of file
diff --git a/backend/tests/test_oasis_profile.py b/backend/tests/test_oasis_profile.py
new file mode 100644
index 00000000..1aa4a534
--- /dev/null
+++ b/backend/tests/test_oasis_profile.py
@@ -0,0 +1,364 @@
+"""
+Unit tests for OasisAgentProfile and helper functions.
+
+These tests verify the profile format conversion logic without requiring
+external dependencies (LLM, Zep, Flask, etc.).
+
+Note: Full integration tests require Flask app initialization and external
+services. These tests focus on isolated logic that can be tested without
+those dependencies.
+
+The OasisAgentProfile class and helper functions are imported from
+oasis_models.py, which is the single source of truth. This ensures tests
+are actually testing the production code, not a copy.
+"""
+
+import sys
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+from importlib.util import spec_from_loader, module_from_spec
+from importlib.machinery import SourceFileLoader
+
+import pytest
+
+# Add backend to path for imports
+backend_path = Path(__file__).parent.parent
+sys.path.insert(0, str(backend_path))
+
+# oasis_models.py has no external dependencies (only stdlib), so we can
+# import it directly without triggering Flask app initialization.
+# This is the key fix - we import the REAL OasisAgentProfile, not a test copy.
+#
+# We use importlib to load the module directly from file to avoid going
+# through the app package which would trigger Flask initialization.
+import importlib
+
+# Clear any cached app modules
+for mod_name in list(sys.modules.keys()):
+    if mod_name.startswith('app'):
+        del sys.modules[mod_name]
+
+# Load oasis_models directly from file
+oasis_models_path = backend_path / "app" / "services" / "oasis_models.py"
+spec = spec_from_loader("oasis_models", SourceFileLoader("oasis_models", str(oasis_models_path)))
+oasis_models = module_from_spec(spec)
+spec.loader.exec_module(oasis_models)
+
+OasisAgentProfile = oasis_models.OasisAgentProfile
+_generate_username = oasis_models._generate_username
+_normalize_gender = oasis_models._normalize_gender
+_is_individual_entity = oasis_models._is_individual_entity
+_is_group_entity = oasis_models._is_group_entity
+INDIVIDUAL_ENTITY_TYPES = oasis_models.INDIVIDUAL_ENTITY_TYPES
+GROUP_ENTITY_TYPES = oasis_models.GROUP_ENTITY_TYPES
+
+
+class TestOasisAgentProfile:
+    """Tests for OasisAgentProfile dataclass."""
+
+    def create_test_profile(
+        self,
+        user_id: int = 0,
+        user_name: str = "test_user",
+        name: str = "Test User",
+        bio: str = "A test user",
+        persona: str = "Test User is enthusiastic",
+        karma: int = 1000,
+        friend_count: int = 100,
+        follower_count: int = 200,
+        statuses_count: int = 500,
+        age: int = 25,
+        gender: str = "male",
+        mbti: str = "INTJ",
+        country: str = "China",
+        profession: str = "Student",
+        interested_topics: list = None,
+        source_entity_uuid: str = "test-uuid-123",
+        source_entity_type: str = "student",
+    ) -> OasisAgentProfile:
+        """Helper to create a test profile with default values."""
+        if interested_topics is None:
+            interested_topics = ["Technology", "Education"]
+        return OasisAgentProfile(
+            user_id=user_id,
+            user_name=user_name,
+            name=name,
+            bio=bio,
+            persona=persona,
+            karma=karma,
+            friend_count=friend_count,
+            follower_count=follower_count,
+            statuses_count=statuses_count,
+            age=age,
+            gender=gender,
+            mbti=mbti,
+            country=country,
+            profession=profession,
+            interested_topics=interested_topics,
+            source_entity_uuid=source_entity_uuid,
+            source_entity_type=source_entity_type,
+        )
+
+    # ===== to_reddit_format() tests =====
+
+    def test_to_reddit_format_basic(self):
+        """Test basic Reddit format conversion."""
+        profile = self.create_test_profile()
+        reddit = profile.to_reddit_format()
+
+        assert reddit["user_id"] == 0
+        assert reddit["username"] == "test_user"
+        assert reddit["name"] == "Test User"
+        assert reddit["bio"] == "A test user"
+        assert reddit["persona"] == "Test User is enthusiastic"
+        assert reddit["karma"] == 1000
+
+    def test_to_reddit_format_includes_optional_fields(self):
+        """Test that optional fields are included when present."""
+        profile = self.create_test_profile(
+            age=30,
+            gender="female",
+            mbti="ENFP",
+            country="USA",
+            profession="Engineer",
+        )
+        reddit = profile.to_reddit_format()
+
+        assert reddit["age"] == 30
+        assert reddit["gender"] == "female"
+        assert reddit["mbti"] == "ENFP"
+        assert reddit["country"] == "USA"
+        assert reddit["profession"] == "Engineer"
+        assert "interested_topics" in reddit
+
+    def test_to_reddit_format_excludes_none_fields(self):
+        """Test that None optional fields are excluded."""
+        profile = self.create_test_profile(
+            age=None,
+            gender=None,
+            mbti=None,
+            country=None,
+            profession=None,
+            interested_topics=[],
+        )
+        reddit = profile.to_reddit_format()
+
+        assert "age" not in reddit
+        assert "gender" not in reddit
+        assert "mbti" not in reddit
+        assert "country" not in reddit
+        assert "profession" not in reddit
+        assert "interested_topics" not in reddit
+
+    def test_to_reddit_format_uses_username_not_user_name(self):
+        """Test that Reddit format uses 'username' key, not 'user_name'."""
+        profile = self.create_test_profile(user_name="test_user")
+        reddit = profile.to_reddit_format()
+
+        assert "username" in reddit
+        assert "user_name" not in reddit
+        assert reddit["username"] == "test_user"
+
+    # ===== to_twitter_format() tests =====
+
+    def test_to_twitter_format_basic(self):
+        """Test basic Twitter format conversion."""
+        profile = self.create_test_profile()
+        twitter = profile.to_twitter_format()
+
+        assert twitter["user_id"] == 0
+        assert twitter["username"] == "test_user"
+        assert twitter["name"] == "Test User"
+        assert twitter["friend_count"] == 100
+        assert twitter["follower_count"] == 200
+        assert twitter["statuses_count"] == 500
+
+    def test_to_twitter_format_includes_optional_fields(self):
+        """Test that optional fields are included when present."""
+        profile = self.create_test_profile(
+            age=30,
+            gender="male",
+            mbti="INTJ",
+            country="UK",
+            profession="Designer",
+        )
+        twitter = profile.to_twitter_format()
+
+        assert twitter["age"] == 30
+        assert twitter["gender"] == "male"
+        assert twitter["mbti"] == "INTJ"
+        assert twitter["country"] == "UK"
+        assert twitter["profession"] == "Designer"
+
+    def test_to_twitter_format_excludes_karma(self):
+        """Test that Reddit-specific karma field is excluded from Twitter format."""
+        profile = self.create_test_profile(karma=5000)
+        twitter = profile.to_twitter_format()
+
+        assert "karma" not in twitter
+
+    # ===== to_dict() tests =====
+
+    def test_to_dict_includes_all_fields(self):
+        """Test that to_dict includes all fields."""
+        profile = self.create_test_profile()
+        d = profile.to_dict()
+
+        assert d["user_id"] == 0
+        assert d["user_name"] == "test_user"
+        assert d["name"] == "Test User"
+        assert d["bio"] == "A test user"
+        assert d["persona"] == "Test User is enthusiastic"
+        assert d["karma"] == 1000
+        assert d["friend_count"] == 100
+        assert d["follower_count"] == 200
+        assert d["statuses_count"] == 500
+        assert d["age"] == 25
+        assert d["gender"] == "male"
+        assert d["mbti"] == "INTJ"
+        assert d["country"] == "China"
+        assert d["profession"] == "Student"
+        assert d["source_entity_uuid"] == "test-uuid-123"
+        assert d["source_entity_type"] == "student"
+
+    def test_to_dict_with_empty_interests(self):
+        """Test to_dict with empty interested_topics."""
+        profile = self.create_test_profile(interested_topics=[])
+        d = profile.to_dict()
+
+        assert d["interested_topics"] == []
+
+    def test_to_dict_with_multiple_interests(self):
+        """Test to_dict with multiple interested_topics."""
+        profile = self.create_test_profile(interested_topics=["AI", "Music", "Travel"])
+        d = profile.to_dict()
+
+        assert d["interested_topics"] == ["AI", "Music", "Travel"]
+
+    # ===== Default values tests =====
+
+    def test_default_karma(self):
+        """Test that karma defaults to 1000."""
+        profile = OasisAgentProfile(
+            user_id=1,
+            user_name="user",
+            name="Name",
+            bio="Bio",
+            persona="Persona",
+        )
+        assert profile.karma == 1000
+
+    def test_default_social_counts(self):
+        """Test default social media counts."""
+        profile = OasisAgentProfile(
+            user_id=1,
+            user_name="user",
+            name="Name",
+            bio="Bio",
+            persona="Persona",
+        )
+        assert profile.friend_count == 100
+        assert profile.follower_count == 150
+        assert profile.statuses_count == 500
+
+    def test_default_created_at_format(self):
+        """Test that created_at is in YYYY-MM-DD format."""
+        import re
+        profile = OasisAgentProfile(
+            user_id=1,
+            user_name="user",
+            name="Name",
+            bio="Bio",
+            persona="Persona",
+        )
+        assert re.match(r"\d{4}-\d{2}-\d{2}", profile.created_at)
+
+
+class TestHelperFunctions:
+    """Tests for helper functions from oasis_models."""
+
+    def test_generate_username_basic(self):
+        """Test username generation from name."""
+        username = _generate_username("John Doe")
+        assert username.startswith("john_doe_")
+        assert len(username.split("_")) == 3  # john, doe, 3-digit-suffix
+
+    def test_generate_username_removes_special_chars(self):
+        """Test that username generation removes special characters."""
+        username = _generate_username("John@Doe#123")
+        assert "@" not in username
+        assert "#" not in username
+        assert username.startswith("johndoe123_")
+
+    def test_generate_username_allows_underscores(self):
+        """Test that underscores are preserved in username."""
+        username = _generate_username("John_Doe_Smith")
+        assert "_" in username
+        assert username.startswith("john_doe_smith_")
+
+
+class TestGenderNormalization:
+    """Tests for gender normalization function."""
+
+    def test_normalize_gender_english(self):
+        """Test gender normalization for English values."""
+        assert _normalize_gender("male") == "male"
+        assert _normalize_gender("female") == "female"
+        assert _normalize_gender("other") == "other"
+
+    def test_normalize_gender_chinese(self):
+        """Test gender normalization for Chinese values."""
+        assert _normalize_gender("男") == "male"
+        assert _normalize_gender("女") == "female"
+        assert _normalize_gender("其他") == "other"
+
+    def test_normalize_gender_none(self):
+        """Test gender normalization for None/empty values."""
+        assert _normalize_gender(None) == "other"
+        assert _normalize_gender("") == "other"
+        assert _normalize_gender("unknown") == "other"
+
+    def test_normalize_gender_case_insensitive(self):
+        """Test that gender normalization is case-insensitive."""
+        assert _normalize_gender("MALE") == "male"
+        assert _normalize_gender("Female") == "female"
+        assert _normalize_gender("OTHER") == "other"
+
+
+class TestEntityTypeDetection:
+    """Tests for entity type detection functions."""
+
+    def test_is_individual_entity_positive(self):
+        """Test individual entity type detection - should be individual."""
+        assert _is_individual_entity("student") is True
+        assert _is_individual_entity("STUDENT") is True
+        assert _is_individual_entity("professor") is True
+        assert _is_individual_entity("person") is True
+        assert _is_individual_entity("alumni") is True
+        assert _is_individual_entity("publicfigure") is True
+        assert _is_individual_entity("expert") is True
+        assert _is_individual_entity("faculty") is True
+
+    def test_is_individual_entity_negative(self):
+        """Test individual entity type detection - should NOT be individual."""
+        assert _is_individual_entity("university") is False
+        assert _is_individual_entity("company") is False
+        assert _is_individual_entity("organization") is False
+        assert _is_individual_entity("ngo") is False
+        assert _is_individual_entity("governmentagency") is False
+
+    def test_is_group_entity_positive(self):
+        """Test group entity type detection - should be group."""
+        assert _is_group_entity("university") is True
+        assert _is_group_entity("UNIVERSITY") is True
+        assert _is_group_entity("company") is True
+        assert _is_group_entity("governmentagency") is True
+        assert _is_group_entity("ngo") is True
+        assert _is_group_entity("mediaoutlet") is True
+
+    def test_is_group_entity_negative(self):
+        """Test group entity type detection - should NOT be group."""
+        assert _is_group_entity("student") is False
+        assert _is_group_entity("professor") is False
+        assert _is_group_entity("person") is False
+        assert _is_group_entity("alumni") is False
\ No newline at end of file