Anyway_config RSpec tests fail with undefined method 'with_config'

I am trying to use anyway_config for the first time in a plain Ruby program with RSpec tests. The docs do not give as much guidance as I would like. The end of this posting shows the pressing issue that I need to solve, plus a related bonus question that would be so helpful to me.

My config class is GitTree::GTConfig.

require "anyway"
require "anyway/testing"

# See https://github.com/palkan/anyway_config?tab=readme-ov-file#usage
module GitTree
  # Enables loading config from `treeconfig.yml` and `treeconfig.local.yml` files.
  # By default, Anyway! looks for yml files in
  # - `./config/treeconfig.yml`
  # - `./.treeconfig.yml`
  # - `~/.config/treeconfig.yml`
  # - `~/.treeconfig.yml`
  class GTConfig < Anyway::Config
    config_name :treeconfig
    Anyway::Settings.default_config_path = "config/treeconfig.yml"

    # All environment variables will be prefixed with `GIT_TREE_`
    env_prefix :git_tree

    # Add required attributes with default values
    attr_config git_timeout:   300,
                verbosity:     ::Logging::NORMAL,
                default_roots: %w[sites sitesUbuntu work]

    # See https://github.com/palkan/anyway_config?tab=readme-ov-file#required-options
    required :git_timeout,
             :verbosity,
             :default_roots

    # See https://github.com/palkan/anyway_config?tab=readme-ov-file#multi-env-configuration
    Anyway::Settings.future.use :unwrap_known_environments

    # See https://github.com/palkan/anyway_config?tab=readme-ov-file#source-tracing
    # Anyway::Settings.enable_source_tracing

    # On_load validators must not accept any arguments
    on_load :validate_environment
    on_load :log_environment

    private

    # Raise RuntimeError if a configuration error
    def validate_environment
      raise "The Anyway::Settings environment is not set" unless Anyway::Settings.current_environment
    end

    def log_environment
      $stdout.puts "Current environment: #{Anyway::Settings.current_environment}" # if Anyway::Settings.verbosity >= ::Logging::VERBOSE
    end
  end
end

config/treeconfig.yml:

test:
  git_timeout: 7
  verbosity: NORMAL
  default_roots:

development:
  git_timeout: 7
  verbosity: NORMAL
  default_roots:

production:
  git_timeout: 300
  verbosity: NORMAL
  default_roots: [sites, sitesUbuntu, work]

This is my RSpec code:

require "spec_helper"
require "anyway/testing"

describe GitTree::GTConfig, type: :config do
  include Anyway::Testing::Helpers

  let(:config) { described_class.new }

  # Reset to default config before each example
  around do |ex|
    with_config(default_roots: %w[a b]) do
      x = ex.run
      puts "x is a #{x.class.name}"
    end
  end

  context "when the environment is not set" do
    it "raises an error" do
      Anyway::Settings.current_environment = nil
      expect { config }.to raise_error(RuntimeError, /Anyway::Settings environment/)
    end
  end

  context "when the environment is set" do
    before do
      Anyway::Settings.current_environment = "test"
    end

    after do
      Anyway::Settings.current_environment = nil
    end

    it "does not raise an error" do
      expect { config }.not_to raise_error
    end

    context "with yaml configuration" do
      it "loads configuration from a YAML file" do
        with_config(default_roots: %w[c d]) do
          expect(config.default_roots).to eq(%w[c d])
        end
      end

      it "loads configuration from a YAML file with a specific location" do
        with_config_path("spec/fixtures/treeconfig.yml") do
          expect(config.default_roots).to eq(%w[e f])
        end
      end
    end

    context "with environment variables" do
      it "loads configuration from environment variables" do
        with_env("GIT_TREE_DEFAULT_ROOTS" => "g h") do
          expect(config.default_roots).to eq(%w[g h])
        end
      end
    end

    context "with source tracing" do
      it "traces the source of the configuration" do
        with_config(default_roots: %w[c d]) do
          expect(config.to_source_trace["default_roots"]).to eq(default: %w[a b], test: { "default_roots" => %w[c d] })
        end
      end
    end
  end
end

The tests all have similar complaints:

NoMethodError:
       undefined method 'with_config' for #<RSpec::ExampleGroups::GitTreeGTConfig::WhenTheEnvironmentIsNotSet:0x000078d34db7aa90>
     # ./spec/git_tree/gt_config_spec.rb:11:in 'block (2 levels) in <top (required)>'
     # ./binstub/rspec:16:in 'Kernel#load'
     # ./binstub/rspec:16:in '<main>'

Furthermore, my program has integer constants defined for verbosity; NORMAL has value 1. How can the text values ("NORMAL") specified in treeconfig.yml be converted to integers when read?