Refactor subject capture

lib/rspec/its.rb

@@ -1,5 +1,6 @@
 # frozen_string_literal: true
 
+require 'rspec/its/subject'
 require 'rspec/its/version'
 require 'rspec/core'
 
@@ -128,20 +129,7 @@ def its(attribute, *options, &block)
       its_caller = caller.grep_v(%r{/lib/rspec/its})
 
       describe(attribute.to_s, caller: its_caller) do
-        let(:__its_subject) do
-          if Array === attribute
-            if Hash === subject
-              attribute.inject(subject) { |inner, attr| inner[attr] }
-            else
-              subject[*attribute]
-            end
-          else
-            attribute_chain = attribute.to_s.split('.')
-            attribute_chain.inject(subject) do |inner_subject, attr|
-              inner_subject.send(attr)
-            end
-          end
-        end
+        let(:__its_subject) { RSpec::Its::Subject.for(attribute, subject) }
 
         def is_expected
           expect(__its_subject)

lib/rspec/its/subject.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+module RSpec
+  module Its
+    # @api private
+    # Handles turning subject into an expectation target
+    module Subject
+      def for(attribute, subject)
+        if Array === attribute
+          if Hash === subject
+            attribute.inject(subject) { |inner, attr| inner[attr] }
+          else
+            subject[*attribute]
+          end
+        else
+          attribute_chain = attribute.to_s.split('.')
+          attribute_chain.inject(subject) do |inner_subject, attr|
+            inner_subject.send(attr)
+          end
+        end
+      end
+
+      module_function :for
+    end
+  end
+end