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

                await AssertEx.Throws<ArgumentNullException>(async () => await client.Get(null, "name", 1));
                await AssertEx.Throws<ArgumentNullException>(async () => await client.Get("owner", null, 1));
            }
            public void RequestsCorrectUrl()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new IssuesClient(connection);

                client.Get("fake", "repo", 42);

                connection.Received().Get<Issue>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42"),
                    null);
            }