config.py

class Config(object):
    DEBUG = False
    TESTING = False
    SQLALCHEMY_DATABASE_URI = "sqlite:///:memory:"

class ProductionConfig(Config):
    SQLALCHEMY_DATABASE_URI = 'mysql://user@localhost/foo'

class DevelopmentConfig(Config):
    DEBUG = True

class TestingConfig(Config):
    TESTING = True
    SQLALCHEMY_TRACK_MODIFICATIONS = False