How do you configure a Sentry raven client in a development environment to not send exceptions and still work?

We are running a Django server and using Sentry to capture exceptions. When we configure Sentry we add RAVEN_CONFIG our different settings.py files:

INSTALLED_APPS = (
    'raven.contrib.django.raven_compat'
)

RAVEN_CONFIG = {
    'dsn': 'https://*****@app.getsentry.com/PORT_NUMBER',
}

We read here that we can just use an empty string DSN property. Though when we run python manage.py raven test as depicted here we get:

raven.exceptions.InvalidDsn: Unsupported Sentry DSN scheme:  ()

The best solution would be that we could always use a Raven client and the settings file would define whether exceptions are sent or not.

Another requirement is that we would like to use the Client module and capture exceptions. For this we have to set some DSN value:

from raven import Client
client = Client('https://<key>:<secret>@app.getsentry.com/<project>')

So not setting a DSN value isn't possible