Proposal: Inform user when testing a private method

features/its.feature

@@ -51,7 +51,7 @@ Feature: attribute of subject
             person
           end
 
-          its("phone_numbers.first") { should eq("555-1212") }
+          its("phone_numbers.first") { is_expected.to eq("555-1212") }
         end
       end
       """

lib/rspec/its.rb

@@ -1,6 +1,14 @@
 require 'rspec/its/version'
 require 'rspec/core'
 
+# RSpec.deprecate <<EOS
+# rspec-its deprecates calling _send_ in favour of _public_send_ internally.
+# This change will be introduced with version 2.0.
+# Maybe you're testing private methods in your test suite without your intention.
+# If you need more information about which test is affected,
+# set `config.its_raise_errors_for_private_method_calling = true`
+# EOS
+
 module RSpec
   module Its
 
@@ -131,6 +139,11 @@ def its(attribute, *options, &block)
           else
             attribute_chain = attribute.to_s.split('.')
             attribute_chain.inject(subject) do |inner_subject, attr|
+
+              if inner_subject.private_methods(false).include?(attr.to_sym)
+                RSpec.deprecate("Testing private method #{attr}", :call_site   => its_caller.first)
+              end
+
               inner_subject.send(attr)
             end
           end
@@ -175,6 +188,11 @@ def should_not(matcher=nil, message=nil)
 end
 
 RSpec.configure do |rspec|
+
+  # Add RSpec configuration setting to allow
+  # the user to handle private method invoking warning
+  rspec.add_setting :its_raise_errors_for_private_method_calling
+
   rspec.extend RSpec::Its
   rspec.backtrace_exclusion_patterns << %r(/lib/rspec/its)
 end

spec/rspec/its_spec.rb

@@ -1,5 +1,12 @@
 require 'spec_helper'
 
+# class RSpec::Core::Formatters::DeprecationFormatter
+#   Formatters.register self, :baem
+
+#   def baem(notification)
+#     output << 'baem'
+#   end
+# end
 module RSpec
   describe Its do
     describe "#its" do
@@ -9,6 +16,37 @@ module RSpec
           its([]) { expect(described_class).to be Its }
         end
       end
+
+      context "raises error when calling a private method" do
+        subject do
+          Class.new do
+            private
+
+            def name
+              'Maria'
+            end
+
+            def self.name
+              'Maria'
+            end
+            private_class_method :name
+          end
+        end
+
+        before(:each) do
+          # expect(RSpec).to receive(:deprecate)
+          #                    .with('Testing private method name is deprecated', anything)
+        end
+
+        context 'on an instance' do
+          its('new.name') { should eq('Maria') }
+        end
+
+        context 'on a class' do
+          its('name') { should eq('Maria') }
+        end
+      end
+
       context "with explicit subject" do
         subject do
           Class.new do

spec/spec_helper.rb

@@ -12,4 +12,8 @@ def method_missing(method, *args, &block)
 RSpec.configure do |config|
   config.run_all_when_everything_filtered = true
   config.order = 'random'
+
+  # config.raise_errors_for_deprecations!
+
+  # config.its_private_method_debug = true
 end