Refactor test cases for improved readability and consistency

- Updated test functions in various test files to enhance code clarity by formatting long lines and improving indentation.
- Adjusted assertions to use multi-line formatting for better readability.
- Added new test cases for theme settings API to ensure proper functionality.
- Ensured consistent use of line breaks and spacing across test files for uniformity.

services/security.py

@@ -0,0 +1,32 @@
+from datetime import datetime, timedelta
+from typing import Any, Union
+
+from jose import jwt
+from passlib.context import CryptContext
+
+
+ACCESS_TOKEN_EXPIRE_MINUTES = 30
+SECRET_KEY = "your-secret-key"  # Change this in production
+ALGORITHM = "HS256"
+
+pwd_context = CryptContext(schemes=["pbkdf2_sha256"], deprecated="auto")
+
+
+def create_access_token(
+    subject: Union[str, Any], expires_delta: Union[timedelta, None] = None
+) -> str:
+    if expires_delta:
+        expire = datetime.utcnow() + expires_delta
+    else:
+        expire = datetime.utcnow() + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
+    to_encode = {"exp": expire, "sub": str(subject)}
+    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
+    return encoded_jwt
+
+
+def verify_password(plain_password: str, hashed_password: str) -> bool:
+    return pwd_context.verify(plain_password, hashed_password)
+
+
+def get_password_hash(password: str) -> str:
+    return pwd_context.hash(password)