pool.rb

action :create do
  chef_gem 'f5-icontrol'

  if pool_does_not_exist?
    converge_by("Create pool #{pool}") do
      create_pool
      Chef::Log.info("#{new_resource} created pool #{pool}")
    end
  end

  if pool_is_missing_node?
    converge_by("Add #{new_resource.host} to pool #{pool}") do
      add_host_to_pool
      Chef::Log.info("#{new_resource} added #{new_resource.host} to pool #{pool}")
    end
  end
end

test.rb

describe 'f5_test::test_create_pool' do

  let(:api) { double('F5::Icontrol') }

  let(:chef_run) { ChefSpec::SoloRunner.new(step_into: ['f5_pool']) do |node|
    node.set[:f5][:credentials][:default] = { host: '1.2.3.4', username: 'api', password: 'testing' }
  end.converge(described_recipe) }

  before do
    allow(F5::Icontrol::API).to receive(:new) { api }
  end

  context 'managing the pool' do
    before do

      allow_any_instance_of(Chef::Provider::F5Pool).to receive(:pool_is_missing_node?).and_return(false)
    end

    context 'the pool does not exist' do
      before do
        allow(api).to receive_message_chain("LocalLB.Pool.get_list") {
          {:item=>["/Common/test1", "/Common/mchan01"], :"@s:type"=>"A:Array", :"@a:array_type"=>"y:string[2]"}
        }
      end