RSpec EQ and Yield

eq_and_yield_matcher.rb

begin
  require "bundler/inline"
rescue LoadError => e
  $stderr.puts "Bundler version 1.10 or later is required. Please update your Bundler"
  raise e
end

gemfile(true) do
  source "https://rubygems.org"

  gem "rspec"
end

require 'rspec/autorun'

RSpec.configure do |rspec|
  rspec.default_formatter = 'doc'
end

# https://twitter.com/kennethmayer/status/1283084667843776515
# Rspec Twitter: Is it possible to write a custom matcher that also yields to a given block?
RSpec.describe do
  RSpec::Matchers.define :eq_and_yield do |expected, blk|
    match do |actual|
       actual == expected
    end

    failure_message_for_should do |actual|
      "expected that actual: #{blk.call(actual)} would be a eq of #{blk.call(expected)}"
    end
  end

  it do
    blk = ->(u) { "arg class: #{u.class}" }
    expect('u').to eq_and_yield(:u, blk)
  end
end

Failures:

  1) is expected to eq and yield :u and #<Proc:0x00007fccd461d6d8 custom_matcher_yield.rb:34 (lambda)>
     Failure/Error: expect('u').to eq_and_yield(:u, blk)
       expected that actual: arg class: String would be a eq of arg class: Symbol
     # custom_matcher_yield.rb:35:in `block (2 levels) in <main>'