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

                await Assert.ThrowsAsync <ArgumentNullException>(() => client.Delete(null, "user"));

                await Assert.ThrowsAsync <ArgumentNullException>(() => client.Delete("org", null));

                await Assert.ThrowsAsync <ArgumentException>(() => client.Delete("", "user"));

                await Assert.ThrowsAsync <ArgumentException>(() => client.Delete("org", ""));
            }
            public void RequestsTheCorrectUrl()
            {
                var connection = Substitute.For <IApiConnection>();
                var client     = new OrganizationOutsideCollaboratorsClient(connection);

                client.Delete("org", "user");

                connection.Connection.Received().Delete(
                    Arg.Is <Uri>(u => u.ToString() == "orgs/org/outside_collaborators/user"),
                    Arg.Any <object>(),
                    "application/vnd.github.korra-preview+json");
            }