Message expectation doesn't leverage passed matcher capabilities when reporting error.

[rfronczyk]

Subject of the issue

Calling expect(...).to receive(...).with(...) with a composed matcher doesn't use the full capabilities of the passed matcher in order to provide a more precise error message to the user.

You can argue that the diff produced in the attached example is correct ( the passed array doesn't match the expected one so the diff include the whole array), that said the other example shows that it could be done better.

Your environment

• Ruby version: ruby-2.4.6
• rspec-mocks version: 3.8.2

Steps to reproduce

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", "3.8.2" # Activate the gem and version you are reporting the issue against.
end

puts "Ruby version is: #{RUBY_VERSION}"
require 'rspec/autorun'

class A
  def test(params)
  end
end

B = Struct.new(:a, :b)

RSpec.describe 'additions' do
  let(:test_double) {  instance_double(A) }

  let(:passed_attributes) do
    [
      B.new(1, 2),
      B.new(3, 4),
      B.new(5, 6),
      B.new(7, 8)
    ]
  end

  let(:attribute_matcher) do
    [
      have_attributes(a: 1, b: 2),
      have_attributes(a: 3, b: 4),
      have_attributes(a: 5, b: 10),
      have_attributes(a: 7, b: 8)
    ]
  end

  it 'shows the whole array instead of elements which dont match' do
    expect(test_double).to receive(:test).with(a_collection_containing_exactly(*attribute_matcher))
    test_double.test(passed_attributes)
  end

  it 'shows only not matching elements' do
    expect(passed_attributes).to contain_exactly(*attribute_matcher)
  end
end

Expected behavior

I would expect that error message shows only elements of the array which don't match the expectation.

Actual behavior

Error message lists the whole array.