public async Task EnsuresNonNullArguments()
            {
                var client = new AssigneesClient(Substitute.For<IApiConnection>());

                await AssertEx.Throws<ArgumentNullException>(async () => await client.GetForRepository(null, "name"));
                await AssertEx.Throws<ArgumentException>(async () => await client.GetForRepository(null, ""));
                await AssertEx.Throws<ArgumentNullException>(async () => await client.GetForRepository("owner", null));
                await AssertEx.Throws<ArgumentException>(async () => await client.GetForRepository("", null));
            }
            public void RequestsCorrectUrl()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new AssigneesClient(connection);

                client.GetForRepository("fake", "repo");

                connection.Received().GetAll<User>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/assignees"));
            }