have_attributes not showing a correct diff when used in a compound matcher

[simonc]

Subject of the issue

When the have_attributes matcher is used as part of a compound matcher, its actual method is not used when building the diff message, resulting in a diff that is not showing the non-matching values. It seems that within a compound matcher the BaseMatcher#actual method is used.

Your environment

• Ruby version: 2.7
• rspec-expectations version: 3.12

Steps to reproduce

Call the have_attributes matcher within a compound matcher.

RSpec.describe 'A simple struct' do
  it 'has an id' do
    obj = Struct.new(:id).new(id: 1)
    expect(obj).to be_a(Struct).and have_attributes(id: 2)
  end
end

Expected behavior

The error message should be

Failure/Error: expect(obj).to be_a(Struct).and have_attributes(id: 2)

  expected #<struct id=1> to have attributes {:id => 2} but had attributes {:id => 1}
  Diff for (have attributes {:id => 2}):
  @@ -1 +1 @@
  -:id => 2,
  +:id => 1,

Actual behavior

The actual message is

Failure/Error: expect(obj).to be_a(Struct).and have_attributes(id: 2)

  expected #<struct id=1> to have attributes {:id => 2} but had attributes {:id => 1}
  Diff for (have attributes {:id => 2}):
  @@ -1 +1 @@
  -:id => 2,
  +"#<struct id=1>"

[pirj]

its actual method is not used when building the diff message

Can you please check what happens if you change this to it se the actual?

before you dive too deep, can you please check if #1440 fixes your case?

[simonc]

Hey @pirj! I upgraded to 3.13 and the issue does seem to be fixed. Thank you! 😊