An example of storing data in SharedStatic.

SharedStaticTests.cs

namespace SomeTests
{
    public class SharedStaticTests : SimpleTestFixture
    {
        public unsafe static class MyData
        {
            private static readonly SharedStatic<Container> SharedData;

            private class Key { }

            static MyData()
            {
                SharedData = SharedStatic<Container>.GetOrCreate<Key>();
            }

            private struct SomeData1
            {
                public UnsafeList Value;
            }

            private struct Container
            {
                public bool SomethingElse;
                public SomeData1 SomeData1;
            }

            public static void SetValue<T>(NativeArray<T> arr) where T : struct
            {
                SharedData.Data.SomeData1.Value = new UnsafeList(arr.GetUnsafePtr(), arr.Length);
            }

            public static ref readonly T GetSome<T>(int index) where T : struct
            {
                return ref UnsafeUtilityEx.ArrayElementAsRef<T>(SharedData.Data.SomeData1.Value.Ptr, index);
            }
        }

        [Test]
        public void Test1()
        {
            var testData = new NativeArray<int>(10, Allocator.Temp);
            for (int i = 0; i < testData.Length; i++)
                testData[i] = i;

            MyData.SetValue(testData);

            Assert.AreEqual(5, MyData.GetSome<int>(5));

            m_World.GetOrCreateSystem<TestSystem>().Update();
        }

        public class TestSystem : SystemBase
        {
            protected override void OnUpdate()
            {
                var result = 0;

                Job.WithCode(() =>
                {
                    result = MyData.GetSome<int>(5);

                }).Run();

                Assert.AreEqual(5, result);
            }
        }
    }

    public class SimpleTestFixture
    {
        protected World m_PreviousWorld;
        protected World m_World;
        protected EntityManager m_Manager;


        [SetUp]
        virtual public void Setup()
        {
            m_PreviousWorld = World.DefaultGameObjectInjectionWorld;
            m_World = World.DefaultGameObjectInjectionWorld = new World("Test World");
            m_Manager = m_World.EntityManager;
        }

        [TearDown]
        virtual public void TearDown()
        {
            if (m_Manager != null)
            {
                m_World.Dispose();
                m_World = null;

                World.DefaultGameObjectInjectionWorld = m_PreviousWorld;
                m_PreviousWorld = null;
                m_Manager = null;
            }
        }
    }
}