Skip to main content

stub_chain

stub_chain is the old way to allow a message chain but carries the baggage of a global monkey patch on all objects. As with receive_message_chain, use with care; we recommend treating usage of stub_chain as a code smell.

Background​

Given a file named "spec/spec_helper.rb" with:

RSpec.configure do |config|
  config.mock_with :rspec do |mocks|
    mocks.syntax = :should
  end
end

And a file named ".rspec" with:

--require spec_helper

Use stub_chain on a double​

Given a file named "spec/stub_chain_spec.rb" with:

RSpec.describe "Using stub_chain on a double" do
  let(:dbl) { double }

  example "using a string and a block" do
    dbl.stub_chain("foo.bar") { :baz }
    expect(dbl.foo.bar).to eq(:baz)
  end

  example "using symbols and a hash" do
    dbl.stub_chain(:foo, :bar => :baz)
    expect(dbl.foo.bar).to eq(:baz)
  end

  example "using symbols and a block" do
    dbl.stub_chain(:foo, :bar) { :baz }
    expect(dbl.foo.bar).to eq(:baz)
  end
end

When I run rspec spec/stub_chain_spec.rb

Then the examples should all pass.

Use stub_chain on any instance of a class​

Given a file named "spec/stub_chain_spec.rb" with:

RSpec.describe "Using any_instance.stub_chain" do
  example "using a string and a block" do
    Object.any_instance.stub_chain("foo.bar") { :baz }
    expect(Object.new.foo.bar).to eq(:baz)
  end

  example "using symbols and a hash" do
    Object.any_instance.stub_chain(:foo, :bar => :baz)
    expect(Object.new.foo.bar).to eq(:baz)
  end

  example "using symbols and a block" do
    Object.any_instance.stub_chain(:foo, :bar) { :baz }
    expect(Object.new.foo.bar).to eq(:baz)
  end
end

When I run rspec spec/stub_chain_spec.rb

Then the examples should all pass.