diff --git a/.gitignore b/.gitignore
index 9aaeae7..1bbc918 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,6 @@
 app/__pycache__
+__pycache__
+.pytest_cache/
 venv/
-test.txt
\ No newline at end of file
+test.txt
+diff.txt
\ No newline at end of file
diff --git a/README.md b/README.md
index 507a444..cf24f59 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ source venv/bin/activate
 
 ## Run locally
 ```bash
-uvicorn app.main:app --reload
+python -m uvicorn app.main:app --reload --host 0.0.0.0 --port 8000
 ```
 Then check:<br> 
 http://127.0.0.1:8000<br>
@@ -23,5 +23,5 @@ http://127.0.0.1:8000/shorten
 ```bash
 PYTHONPATH=./ pytest
 export PYTHONPATH=$(pwd)
-pytest
+python -m pytest --cov=app --cov-report=term-missing
 ```
\ No newline at end of file
diff --git a/app/core/config.py b/app/core/config.py
index f55452d..54c8793 100644
--- a/app/core/config.py
+++ b/app/core/config.py
@@ -1,36 +1,38 @@
 # app/core/config.py
 
 from functools import lru_cache
-from pydantic_settings import BaseSettings, SettingsConfigDict
+from pydantic import BaseSettings
+from typing import List
 
 
 class Settings(BaseSettings):
-    # App
-    app_name: str = "URL Shortener API"
-    debug: bool = False
+    app_name: str = "URL Shortener"
+    allowed_hosts: List[str] = ["*"]
+    database_url: str
 
-    # Server
+    # Server settings
     host: str = "0.0.0.0"
     port: int = 8000
     base_url: str = "http://localhost:8000"
 
-    # Database
-    database_url: str = "sqlite:///./urls.db"
-
+    # Debug flag
+    debug: bool = True
+    
     # Optional future extensions
-    allowed_hosts: list[str] = ["*"]
     rate_limit_per_minute: int = 60
 
-    model_config = SettingsConfigDict(
-        env_file=".env",
-        env_file_encoding="utf-8",
-        case_sensitive=False,
-        extra="ignore",
-    )
+    class Config:
+        env_file = ".env"
+        env_file_encoding = "utf-8"
+        case_sensitive = False
+        extra = "ignore"
 
-@lru_cache
+
+# Cached singleton-style access
+@lru_cache()
 def get_settings() -> Settings:
     return Settings()
 
-# Singleton-style access
+
+# Global settings instance
 settings = get_settings()
\ No newline at end of file
diff --git a/app/db/models.py b/app/db/models.py
index 207dc07..f3c37e5 100644
--- a/app/db/models.py
+++ b/app/db/models.py
@@ -4,7 +4,7 @@ from sqlalchemy import String, Integer, DateTime, func, Index
 from sqlalchemy.orm import Mapped, mapped_column
 from datetime import datetime
 from app.db.base import Base
-
+from typing import Optional
 
 class URL(Base):
     __tablename__ = "urls"
@@ -40,7 +40,7 @@ class URL(Base):
         nullable=False
     )
 
-    last_accessed: Mapped[datetime | None] = mapped_column(
+    last_accessed: Mapped[Optional[datetime]] = mapped_column(
         DateTime(timezone=True),
         nullable=True
     )
diff --git a/app/services/url_service.py b/app/services/url_service.py
index f537085..7c2300d 100644
--- a/app/services/url_service.py
+++ b/app/services/url_service.py
@@ -9,7 +9,6 @@ from app.db.models import URL
 from app.utils.short_code import generate_short_code
 from app.core.config import settings
 
-
 SHORT_CODE_LENGTH = 6
 MAX_GENERATION_ATTEMPTS = 5
 
diff --git a/app/test_main.py b/app/test_main.py
index 9355bf4..bfe170a 100644
--- a/app/test_main.py
+++ b/app/test_main.py
@@ -4,7 +4,7 @@ import os
 
 sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '..')))
 from app.main import app
-from app import settings
+from app.core.config import settings
 import tempfile
 import pytest
 
diff --git a/app/utils/__init__.py b/app/utils/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/app/utils/short_code.py b/app/utils/short_code.py
new file mode 100644
index 0000000..54cc355
--- /dev/null
+++ b/app/utils/short_code.py
@@ -0,0 +1,8 @@
+# app/utils/short_code.py
+import string
+import random
+
+def generate_short_code(length: int = 6) -> str:
+    """Generate a random alphanumeric short code."""
+    chars = string.ascii_letters + string.digits
+    return ''.join(random.choices(chars, k=length))
\ No newline at end of file
diff --git a/test.db b/test.db
new file mode 100644
index 0000000..efee9ea
Binary files /dev/null and b/test.db differ