til/ruby/assert-about-an-objects-attributes-with-rspec.md

Assert About An Object's Attributes With RSpec

When testing an object that gets created as the result of some process, it can be useful to assert about the attributes of that object. Not all of the attributes are relevant and some can be hard to reliably test. Rather than asserting about the result of calling #attributes or #to_h on an object, we can focus in with the have_attributes matcher provided by RSpec.

RSpec.describe "have_attributes" do
  it "can assert on an ActiveRecord object" do
    book = Book.create(title: "Fledling", isbn: "123")

    expect(book).to have_attributes(title: "Fledgling", isbn: "123")
  end

  it "can assert on a Struct" do
    Name = Struct.new(:first, :last)
    some_name = Name.new("Liz", "Lemon")

    expect(some_name).to have_attributes(first: "Liz")
  end
end

In this example we were able to assert about all or just a subset of the attributes on both an ActiveRecord object and a Struct.

See the docs for more details.