make celery a required dependency and the celery extra's optional dependencies

src/pytest_celery/__init__.py

@@ -24,17 +24,27 @@
 from pytest_celery.fixtures.broker import *
 from pytest_celery.fixtures.setup import *
 from pytest_celery.fixtures.worker import *
-from pytest_celery.vendors.memcached.api import *
-from pytest_celery.vendors.memcached.container import *
-from pytest_celery.vendors.memcached.fixtures import *
+from pytest_celery.vendors import MissingCeleryDependency
 from pytest_celery.vendors.rabbitmq.api import *
 from pytest_celery.vendors.rabbitmq.container import *
 from pytest_celery.vendors.rabbitmq.fixtures import *
-from pytest_celery.vendors.redis.backend.api import *
-from pytest_celery.vendors.redis.backend.fixtures import *
-from pytest_celery.vendors.redis.broker.api import *
-from pytest_celery.vendors.redis.broker.fixtures import *
-from pytest_celery.vendors.redis.container import *
+
+try:
+    from pytest_celery.vendors.memcached.api import *
+    from pytest_celery.vendors.memcached.container import *
+    from pytest_celery.vendors.memcached.fixtures import *
+except MissingCeleryDependency:
+    pass
+
+try:
+    from pytest_celery.vendors.redis.backend.api import *
+    from pytest_celery.vendors.redis.backend.fixtures import *
+    from pytest_celery.vendors.redis.broker.api import *
+    from pytest_celery.vendors.redis.broker.fixtures import *
+    from pytest_celery.vendors.redis.container import *
+except MissingCeleryDependency:
+    pass
+
 from pytest_celery.vendors.worker.container import *
 from pytest_celery.vendors.worker.fixtures import *
 

src/pytest_celery/defaults.py

@@ -4,18 +4,35 @@
 
 from pytest_docker_tools import network
 
-from pytest_celery.vendors.memcached.defaults import CELERY_MEMCACHED_BACKEND
-from pytest_celery.vendors.memcached.defaults import *
+from pytest_celery.vendors import MissingCeleryDependency
 from pytest_celery.vendors.rabbitmq.defaults import CELERY_RABBITMQ_BROKER
 from pytest_celery.vendors.rabbitmq.defaults import *
-from pytest_celery.vendors.redis.backend.defaults import CELERY_REDIS_BACKEND
-from pytest_celery.vendors.redis.backend.defaults import *
-from pytest_celery.vendors.redis.broker.defaults import CELERY_REDIS_BROKER
-from pytest_celery.vendors.redis.broker.defaults import *
-from pytest_celery.vendors.redis.defaults import *
 from pytest_celery.vendors.worker.defaults import CELERY_SETUP_WORKER
 from pytest_celery.vendors.worker.defaults import *
 
+try:
+    import pytest_celery.vendors.memcached
+except MissingCeleryDependency:
+    _CELERY_MEMCACHED_BACKEND = None
+else:
+    from pytest_celery.vendors.memcached.defaults import CELERY_MEMCACHED_BACKEND as _CELERY_MEMCACHED_BACKEND
+    from pytest_celery.vendors.memcached.defaults import *
+
+    _CELERY_MEMCACHED_BACKEND = None  # Beta support at the moment, to be used manually
+
+try:
+    import pytest_celery.vendors.redis
+except MissingCeleryDependency:
+    _CELERY_REDIS_BACKEND = None
+    _CELERY_REDIS_BROKER = None
+else:
+    from pytest_celery.vendors.redis.backend.defaults import CELERY_REDIS_BACKEND as _CELERY_REDIS_BACKEND
+    from pytest_celery.vendors.redis.backend.defaults import *
+    from pytest_celery.vendors.redis.broker.defaults import CELERY_REDIS_BROKER as _CELERY_REDIS_BROKER
+    from pytest_celery.vendors.redis.broker.defaults import *
+    from pytest_celery.vendors.redis.defaults import *
+
+
 ####################################################################################
 # Automatic components
 ####################################################################################
@@ -29,14 +46,8 @@
 # Tests that do not rely on default parametrization will not be affected.
 
 ALL_CELERY_WORKERS = (CELERY_SETUP_WORKER,)
-ALL_CELERY_BACKENDS = (
-    CELERY_REDIS_BACKEND,
-    # CELERY_MEMCACHED_BACKEND,  # Beta support at the moment, to be used manually
-)
-ALL_CELERY_BROKERS = (
-    CELERY_REDIS_BROKER,
-    CELERY_RABBITMQ_BROKER,
-)
+ALL_CELERY_BACKENDS = (backend for backend in [_CELERY_REDIS_BACKEND, _CELERY_MEMCACHED_BACKEND] if backend is not None)
+ALL_CELERY_BROKERS = (broker for broker in [CELERY_RABBITMQ_BROKER, _CELERY_REDIS_BROKER] if broker is not None)
 
 ####################################################################################
 # Fixtures

src/pytest_celery/vendors/__init__.py

@@ -1 +1,5 @@
 """See :ref:`vendors`."""
+
+
+class MissingCeleryDependency(ImportError):
+    pass

src/pytest_celery/vendors/memcached/__init__.py

@@ -3,3 +3,10 @@
 
 This module is part of the Memcached Backend vendor.
 """
+
+from .. import MissingCeleryDependency
+
+try:
+    import memcache  # noqa F401
+except ImportError as e:
+    raise MissingCeleryDependency("celery extra dependency missing: celery[pymemcache]") from e

src/pytest_celery/vendors/redis/__init__.py

@@ -3,3 +3,10 @@
 
 This module is part of the Redis vendor.
 """
+
+from .. import MissingCeleryDependency
+
+try:
+    import redis  # noqa F401
+except ImportError as e:
+    raise MissingCeleryDependency("celery extra dependency missing: celery[redis]") from e