gistfile1.txt

from _pytest.core import PluginManager

pm = PluginManager("devpi_server")

class MyHooks:
    def devpi_server_whatever(self, arg1):
        pass

pm.addhooks(MyHooks)

class MyPlugin1:
    def devpi_server_whatever(self, arg1):
        return arg1 + 1

pm.register(MyPlugin1())

class MyPlugin2:
    def devpi_server_whatever(self, arg1):
        return arg1 + 10

pm.register(MyPlugin2())

res = pm.hook.devpi_server_whatever(arg1=17)
print "result", res
assert res == [27, 18]