6.5Testing Computed/Derived Values

Some systems compute values in the database (materialized views, generated columns):

def test_user_order_count_computed(db):
    """Verify computed order_count matches actual orders."""
    cursor = db.cursor()

    # Create user with orders
    cursor.execute("INSERT INTO users (id, name, email) VALUES ('count-test', 'Count User', 'count@test.com')")
    cursor.execute("""
        INSERT INTO orders (user_id, status, total) VALUES
        ('count-test', 'completed', 50.00),
        ('count-test', 'completed', 75.00),
        ('count-test', 'cancelled', 25.00)
    """)

    # If there is a materialized view or computed column:
    cursor.execute("SELECT order_count FROM user_stats WHERE user_id = 'count-test'")
    computed_count = cursor.fetchone()[0]

    # Verify against actual count
    cursor.execute("SELECT COUNT(*) FROM orders WHERE user_id = 'count-test'")
    actual_count = cursor.fetchone()[0]

    assert computed_count == actual_count