public async Task RoleStorePublicNullCheckTest()
        {
            Assert.Throws <ArgumentNullException>("db", () => new FirestoreRoleStore <IdentityRole>(null));
            var store = new FirestoreRoleStore <IdentityRole>(new Mock <IFirestoreDbContext>().Object);
            await Assert.ThrowsAsync <ArgumentNullException>("role", async() => await store.GetRoleIdAsync(null));

            await Assert.ThrowsAsync <ArgumentNullException>("role", async() => await store.GetRoleNameAsync(null));

            await Assert.ThrowsAsync <ArgumentNullException>("role", async() => await store.SetRoleNameAsync(null, null));

            await Assert.ThrowsAsync <ArgumentNullException>("role", async() => await store.CreateAsync(null));

            await Assert.ThrowsAsync <ArgumentNullException>("role", async() => await store.UpdateAsync(null));

            await Assert.ThrowsAsync <ArgumentNullException>("role", async() => await store.DeleteAsync(null));
        }
        public async Task RoleStoreMethodsThrowWhenDisposedTest()
        {
            var store = new FirestoreRoleStore <IdentityRole>(new Mock <IFirestoreDbContext>().Object);

            store.Dispose();
            await Assert.ThrowsAsync <ObjectDisposedException>(async() => await store.FindByIdAsync(null));

            await Assert.ThrowsAsync <ObjectDisposedException>(async() => await store.FindByNameAsync(null));

            await Assert.ThrowsAsync <ObjectDisposedException>(async() => await store.GetRoleIdAsync(null));

            await Assert.ThrowsAsync <ObjectDisposedException>(async() => await store.GetRoleNameAsync(null));

            await Assert.ThrowsAsync <ObjectDisposedException>(async() => await store.SetRoleNameAsync(null, null));

            await Assert.ThrowsAsync <ObjectDisposedException>(async() => await store.CreateAsync(null));

            await Assert.ThrowsAsync <ObjectDisposedException>(async() => await store.UpdateAsync(null));

            await Assert.ThrowsAsync <ObjectDisposedException>(async() => await store.DeleteAsync(null));
        }