Samarche

API checker inspired by this post

Quickstart

Say you're developping a module with a public API, for people working with it, this API is supposed to stay the same until the next major release. What would happen if a commit makes a change it shouldn't have ?

The solution is testing :

# A class which is part of your API
class Foo:
    bar = True
    def __init__(self, stuff=False):
        self.stuff

    def thing(self):
        return "doh"

# Your tests to make sure the class stays consistent
self.assertTrue(hasattr(Foo, 'bar'))
self.assertTrue(hasattr(Foo, 'thing'))
self.assertTrue(hasattr(Foo(), 'stuff'))

Unfortunatly those tests are basically writting all your API a second time, there must be a better (and less boring) way !

Samarche allow you to take a snapshop of your API (called a signature) and then be able to test your evolving codebase against it.

Samarche register only public members (i.e. everything starting by _ is skipped) You can create signatures from a module, module.package and even module.package:package_attribute

Example

First build and save the signature of your API:

# Do this at each major release
import samarche

signature = samarche.build_signature("my_api")
with open('my_api.signature', 'wb') as fd:
    samarche.dump(signature, f)

Then put somewhere in your tests

with open('my_api.signature', 'rb') as fd:
  original_signature = samarche.load(fd)
try:
    samarche.check_signature('my_api', original_signature)
except samarche.ValidationError as e:
    print("API has changed : {}".format(e))