Fix: Test Ray only when installed

import numpy as np

@unittest.skipUnless((3, 8) <= sys.version_info <= (3, 12),

                     "Support Ray only for Python 3.8-3.11")

has_ray: bool = False

try:

    import ray

    has_ray = True

except ImportError:

    pass

@unittest.skipUnless(has_ray, "Ray is not installed")

class TestRay(unittest.TestCase):

    @classmethod

    def setUpClass(cls):

        import ray

        cls.m = mp.get_context().Manager()

        ray.init()

    @classmethod

    def tearDownClass(cls):

        import ray

        ray.shutdown()

        cls.m.shutdown()

    def test_er(self):

        import ray

        rb = MPReplayBuffer(10, {"done": {}}, ctx=self.m, backend="SharedMemory")

        @ray.remote

        self.assertEqual(s["done"].shape[0], 2)

    def test_per(self):

        import ray

        rb = MPPrioritizedReplayBuffer(10, {"done": {}},

                                       ctx=self.m, backend="SharedMemory")

        self.assertEqual(s["done"].shape[0], 2)

    def test_with_alpha(self):

        import ray

        rb = MPPrioritizedReplayBuffer(10, {"done": {}}, alpha=0.2,

                                       ctx=self.m, backend="SharedMemory")