Project: RSpec Mocks 2.11

Publisher: RSpec

stub a chain of methods

Use the stub_chain method to stub a chain of two or more methods in one
statement. Method chains are considered a design smell, but it's not really
the method chain itself that is the problem - it's the dependency chain
represented by a chain of messages to different objects:

foo.get_bar.get_baz

This is a Law of Demeter violation if get_bar returns an object other than
foo, and get_baz returns yet another object.

Fluent interfaces look similar from a caller's perspective, but don't
represent a dependency chain (the caller depends only on the object it is
calling). Consider this common example from Ruby on Rails:

Article.recent.by(current_user)

The recent and by methods return the same object, so this is not a Law of
Demeter violation.

Scenarios

stub a chain of methods

Given

a file named "stub_chain_spec.rb" with:

describe "stubbing a chain of methods" do
  subject { Object.new }

  context "given symbols representing methods" do
    it "returns the correct value" do
      subject.stub_chain(:one, :two, :three).and_return(:four)
      subject.one.two.three.should eq(:four)
    end
  end

  context "given a hash at the end" do
    it "returns the correct value" do
      subject.stub_chain(:one, :two, :three => :four)
      subject.one.two.three.should eq(:four)
    end
  end

  context "given a string of methods separated by dots" do
    it "returns the correct value" do
      subject.stub_chain("one.two.three").and_return(:four)
      subject.one.two.three.should eq(:four)
    end
  end
end

When

I run rspec stub_chain_spec.rb

Then

the examples should all pass

Last published about 7 years ago by dchelimsky.

stub a chain of methods

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