Automatically install default content types in tests on Plone 5

I've been trying to add compatibility with Plone 5 in some of our add-ons and I found a pattern that I want to avoid: seem that I have to manually install default content types on test fixture like this:

...
PLONE_VERSION = api.env.plone_version()


class Fixture(PloneSandboxLayer):

    defaultBases = (PLONE_FIXTURE,)

    def setUpZope(self, app, configurationContext):
        if PLONE_VERSION >= '5.0':
            import plone.app.contenttypes
            self.loadZCML(package=plone.app.contenttypes)
        ...

    def setUpPloneSite(self, portal):
        if PLONE_VERSION >= '5.0':
            self.applyProfile(portal, 'plone.app.contenttypes:default')
        ...

FIXTURE = Fixture()
...

Is there any way to avoid this?

As far as I remember it is enough to depend on PLONE_APP_CONTENTTYPES_FIXTURE. Something like this (untested):

try:
    from plone.app.contenttypes.testing import PLONE_APP_CONTENTTYPES_FIXTURE
except ImportError:
    PLONE_APP_CONTENTTYPES_FIXTURE = None


class Fixture(PloneSandboxLayer):
    if PLONE_VERSION >= '5.0':
        defaultBases = (PLONE_APP_CONTENTTYPES_FIXTURE,)
    else:
        defaultBases = (PLONE_FIXTURE,)