Quickstart

Basic usage

Suppose we have a foo function which reads a bar argument and writes it to file:

def foo(bar):
    with open("/tmp/antani.txt", "w") as f:
        f.write(bar)

Dryrun mode is easily achievable using the sham decorator:

from drypy.patterns import sham

@sham
def foo(bar, baz=False):
    ...

Turning on drypy it’s enough to make it log the following message instead of executing foo:

>>> from drypy import dryrun
>>> dryrun(True)
>>> foo(42)
[DRYRUN] call to 'foo(42)'

Note

drypy uses the python standard logging library therefore you will need to setup valid handlers in order to get the messages.

drypy logs messages with the logging.INFO level.

Custom substitute

Sometimes we may have complex situations we want to manage in a custom way providing a complete substitute to the original function. The sheriff-deputy pattern comes here in help:

from drypy.patterns import sheriff

@sheriff
def foo(bar):
    # do this and that
    pass

@foo.deputy
def foo(bar):
    # do this
    # DON'T do that
    # log a message
    pass

When drypy dryrun mode is set to True, the function marked by foo.deputy will be executed in place of the fisrt defined foo.

Important

Since the deputy function will receive the same args you are passing to the sheriff, it’s advised that the two function signatures correspond. Otherwise, if you think that the sheriff function signature may change in the future, you can use the generic syntax *args, **kw for the deputy args.

Dryrun with mock

Sometimes we have a requirement to dryrun a function but also need to mock its return value. You can use sham decorator with args for this purpose:

from drypy.patterns import sham

@sham(return_value=42)
def foo(bar):
    return 12

Turning on drypy dryrun mode will now also mock the return value of foo along with skipping execution and logging the call:

>>> from drypy import dryrun
>>> dryrun(True)
>>> result = foo("anything")
[DRYRUN] call to 'foo("anything")'
>>> result
42

Note

drypy uses the python standard logging library therefore you will need to setup valid handlers in order to get the messages.

drypy logs messages with the logging.INFO level.

Warning

A custom return value used to be handled by the sentinel decorator: It is now deprecated and it will be removed soon. Please use sham with arguments instead, as shown in the example above. See drypy.patterns.sham() for more details.