📝 Add an example of setting up a test database (#1144)

* Add an example of setting up a test database.

* 📝 Add/update docs for testing a DB with dependency overrides

* 🔧 Update test script, remove line removing test file as it is removed during testing

* ✅ Update testing coverage pragma

Co-authored-by: Sebastián Ramírez <tiangolo@gmail.com>

docs_src/sql_databases/sql_app/database.py

@@ -2,7 +2,7 @@ from sqlalchemy import create_engine
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import sessionmaker
 
-SQLALCHEMY_DATABASE_URL = "sqlite:///./test.db"
+SQLALCHEMY_DATABASE_URL = "sqlite:///./sql_app.db"
 # SQLALCHEMY_DATABASE_URL = "postgresql://user:password@postgresserver/db"
 
 engine = create_engine(