Merge pull request #187 from bquorning/message-chain-cop

Add MessageChain cop disallowing stubbed chains

CHANGELOG.md

@@ -20,6 +20,7 @@
 * Add `BeEql` cop which looks for expectations that can use `be(...)` instead of `eql(...)`. ([@backus][])
 * Add autocorrect support for `BeEql` cop. ([@backus][])
 * Add `MessageExpectation` cop for enforcing consistent style of either `expect(...).to receive` or `allow(...).to receive`. ([@backus][])
+* Add `MessageChain` cop. ([@bquorning][])
 
 ## 1.6.0 (2016-08-03)
 

config/default.yml

@@ -53,6 +53,10 @@ RSpec/ExpectActual:
   Description: Checks for `expect(...)` calls containing literal values.
   Enabled: true
 
+RSpec/MessageChain:
+  Description: Check that chains of messages are not being stubbed.
+  Enabled: true
+
 RSpec/MultipleDescribes:
   Description: Checks for multiple top level describes.
   Enabled: true

lib/rubocop-rspec.rb

@@ -31,6 +31,7 @@
 require 'rubocop/cop/rspec/instance_variable'
 require 'rubocop/cop/rspec/leading_subject'
 require 'rubocop/cop/rspec/let_setup'
+require 'rubocop/cop/rspec/message_chain'
 require 'rubocop/cop/rspec/message_expectation'
 require 'rubocop/cop/rspec/multiple_describes'
 require 'rubocop/cop/rspec/multiple_expectations'

lib/rubocop/cop/rspec/message_chain.rb

@@ -0,0 +1,33 @@
+module RuboCop
+  module Cop
+    module RSpec
+      # Check that chains of messages are not being stubbed.
+      #
+      # @example
+      #   # bad
+      #   allow(foo).to receive_message_chain(:bar, :baz).and_return(42)
+      #
+      #   # better
+      #   thing = Thing.new(baz: 42)
+      #   allow(foo).to receive(bar: thing)
+      #
+      class MessageChain < Cop
+        include RuboCop::RSpec::SpecOnly
+
+        MESSAGE = 'Avoid stubbing using `%<method>s`'.freeze
+
+        MESSAGE_CHAIN_METHODS = [
+          :receive_message_chain,
+          :stub_chain
+        ].freeze
+
+        def on_send(node)
+          _receiver, method_name, *_args = *node
+          return unless MESSAGE_CHAIN_METHODS.include?(method_name)
+
+          add_offense(node, :selector, MESSAGE % { method: method_name })
+        end
+      end
+    end
+  end
+end

spec/rubocop/cop/rspec/message_chain_spec.rb

@@ -0,0 +1,21 @@
+describe RuboCop::Cop::RSpec::MessageChain do
+  subject(:cop) { described_class.new }
+
+  it 'finds `receive_message_chain`' do
+    expect_violation(<<-RUBY)
+      before do
+        allow(foo).to receive_message_chain(:one, :two) { :three }
+                      ^^^^^^^^^^^^^^^^^^^^^ Avoid stubbing using `receive_message_chain`
+      end
+    RUBY
+  end
+
+  it 'finds old `stub_chain` syntax' do
+    expect_violation(<<-RUBY)
+      before do
+        foo.stub_chain(:one, :two).and_return(:three)
+            ^^^^^^^^^^ Avoid stubbing using `stub_chain`
+      end
+    RUBY
+  end
+end