webmock 1.5.2 stub_request + hash_including spec failing

stub_hash_including_spec.rb

require 'spec_helper'
require 'rest-client'

describe WebMock::API do
  describe '#stub_request with hash_including' do


    context "when setting 'hash_including' with an hash" do 
      before do 
        WebMock::API.stub_request(:post, 'www.example.com').
          with(:body => WebMock::API.hash_including(:data => {:a => '1', :b => 'five'})).
          to_return(:status => 200, :body => "abc", :headers => {})
      end

      it "responds if the hash matches" do
        response = RestClient.post('www.example.com', "data[a]=1&data[b]=five&x=1", 
          :content_type => 'application/x-www-form-urlencoded') 
        expect(response.body).to match('abc')
      end

      #hashes always become an empty hash which always matches true 
      it "SHOULD FAIL BUT IT DOESN'T" do
        response = RestClient.post('www.example.com', "data[a]=1&data[b]=five&x=1", 
          :content_type => 'application/x-www-form-urlencoded') 
        expect(response.body).to match('abc')
      end
    end

    context "when setting 'hash_including' with solitary keys" do 
      before do 
        WebMock::API.stub_request(:post, 'www.example.com').
          with(:body => WebMock::API.hash_including(:a, :b)).
          to_return(:status => 200, :body => "abc", :headers => {})
      end

      it "responds to any solitary keys' value" do
        response = RestClient.post('www.example.com', "a=1&b=five", 
          :content_type => 'application/x-www-form-urlencoded') 
        expect(response.body).to match('abc')
      end

      #solitary keys become an empty hash which always matches true 
      it "SHOULD FAIL BUT IT DOESN'T" do
        response = RestClient.post('www.example.com', "fail", 
          :content_type => 'application/x-www-form-urlencoded') 
        expect(response.body).to match('abc')
      end
    end

    context "when setting 'hash_including' with both solitary keys and a specific hash" do 
      subject { RestClient.post('www.example.com', "a=1&b=five&data=2", 
          :content_type => 'application/x-www-form-urlencoded') }

      #this FAILS
      context "when using 'WebMock::API#hash_including'" do 
        it "responds to any solitary keys' value and if the hash matches" do
          WebMock::API.stub_request(:post, 'www.example.com').
            with(:body => WebMock::API.hash_including(:a, :b, :data => '2')).
            to_return(:status => 200, :body => "abc", :headers => {})
          expect(subject.body).to match('abc')
        end
      end

      context "when using 'RSpec:Mocks::ArgumentMatchers#hash_including'" do
        it "responds to any solitary keys' value and if the hash matches" do
          WebMock::API.stub_request(:post, 'www.example.com').
            with(:body => hash_including(:a, :b, :data => '2')). 
            to_return(:status => 200, :body => "abc", :headers => {})
          expect(subject.body).to match('abc')
        end
      end
    end

    context "when setting an empty 'hash_including'" do
      before do 
        WebMock::API.stub_request(:post, 'www.example.com').
          with(:body => WebMock::API.hash_including({})).
          to_return(:status => 200, :body => "abc", :headers => {})
      end

      it "responds to an empty body" do
        response = RestClient.post('www.example.com', "", 
          :content_type => 'application/x-www-form-urlencoded')
        expect(response.body).to match('abc')
      end

      #this FAILS because the comparison between {} and {data: ...} always returns true 
      it "raises an error as a response to a body containing some data" do
        lambda { RestClient.post('www.example.com', "data=1", 
          :content_type => 'application/x-www-form-urlencoded') }.should raise_error
      end
    end

  end  #end of describe 
end  #end of describe