Fixed bug where subject (implicit and explicit) were not being exposed

[#744 state:resolved milestone:'Next Release']

features/subject/explicit_subject.feature

@@ -0,0 +1,31 @@
+Feature: explicit subject
+
+  You can override the implicit subject using the subject() method.
+
+  Scenario: subject in top level group
+    Given the following spec:
+      """
+      describe Array, "with some elements" do
+        subject { [1,2,3] }
+        it "should have the prescribed elements" do
+          subject.should == [1,2,3]
+        end
+      end
+      """
+    When I run it with the spec command
+    Then the stdout should match "1 example, 0 failures"
+
+  Scenario: subject in a nested group
+    Given the following spec:
+      """
+      describe Array do
+        subject { [1,2,3] }
+        describe "with some elements" do
+          it "should have the prescribed elements" do
+            subject.should == [1,2,3]
+          end
+        end
+      end
+      """
+    When I run it with the spec command
+    Then the stdout should match "1 example, 0 failures"

features/subject/implicit_subject.feature

@@ -0,0 +1,31 @@
+Feature: implicit subject
+
+  The first argument to the outermost example group block is
+  made available to each example as an implicit subject of
+  that example.
+
+  Scenario: subject in top level group
+    Given the following spec:
+      """
+      describe Array, "when first created" do
+        it "should be empty" do
+          subject.should == []
+        end
+      end
+      """
+    When I run it with the spec command
+    Then the stdout should match "1 example, 0 failures"
+
+  Scenario: subject in a nested group
+    Given the following spec:
+      """
+      describe Array do
+        describe "when first created" do
+          it "should be empty" do
+            subject.should == []
+          end
+        end
+      end
+      """
+    When I run it with the spec command
+    Then the stdout should match "1 example, 0 failures"

lib/spec/example/subject.rb

@@ -15,13 +15,24 @@ module ExampleGroupMethods
         #
         # See +ExampleMethods#should+ for more information about this approach.
         def subject(&block)
-          if block.nil?
-            defined?(@_subject_block) ? @_subject_block :
-              (described_class ? lambda {described_class.new} : lambda {description_args.first})
+          block.nil? ?
+            explicit_subject || implicit_subject :
+            @_explicit_subject_block = block
+        end
+
+        def explicit_subject
+          if defined?(@_explicit_subject_block)
+            @_explicit_subject_block
+          elsif super_subject = superclass.instance_variable_get('@_explicit_subject_block')
+            super_subject
           else
-            @_subject_block = block
+            nil
           end
         end
+
+        def implicit_subject
+          (described_class ? lambda {described_class.new} : lambda {description_args.first})
+        end
       end
 
       module ExampleMethods

spec/spec/example/example_methods_spec.rb

@@ -56,36 +56,6 @@ def module_that_is_reopened_method; end
         end
       end
 
-      describe "#subject" do
-        before(:each) do
-          @example_group = ExampleGroupDouble
-        end
-
-        it "should return an instance of the described class" do
-          group = Class.new(ExampleGroupDouble).describe(Array)
-          example = group.new(ExampleProxy.new)
-          example.subject.should == []
-        end
-
-        it "should return a Module" do
-          group = Class.new(ExampleGroupDouble).describe(Enumerable)
-          example = group.new(ExampleProxy.new)
-          example.subject.should == Enumerable
-        end
-
-        it "should return a string" do
-          group = Class.new(ExampleGroupDouble).describe('foo')
-          example = group.new(ExampleProxy.new)
-          example.subject.should == 'foo'
-        end
-
-        it "should return a number" do
-          group = Class.new(ExampleGroupDouble).describe(15)
-          example = group.new(ExampleProxy.new)
-          example.subject.should == 15
-        end
-      end
-
       describe "#should" do
         before(:each) do
           @example_group = Class.new(ExampleGroupDouble)

spec/spec/example/subject_spec.rb

@@ -0,0 +1,77 @@
+require File.dirname(__FILE__) + '/../../spec_helper'
+
+module Spec
+  module Example
+    describe "implicit subject" do
+      describe "with a class" do
+        it "returns an instance of the class" do
+          group = Class.new(ExampleGroupDouble).describe(Array)
+          example = group.new(ExampleProxy.new)
+          example.subject.should == []
+        end
+      end
+
+      describe "with a Module" do
+        it "returns the Module" do
+          group = Class.new(ExampleGroupDouble).describe(Enumerable)
+          example = group.new(ExampleProxy.new)
+          example.subject.should == Enumerable
+        end
+      end
+
+      describe "with a string" do
+        it "return the string" do
+          group = Class.new(ExampleGroupDouble).describe('foo')
+          example = group.new(ExampleProxy.new)
+          example.subject.should == 'foo'
+        end
+      end
+
+      describe "with a number" do
+        it "returns the number" do
+          group = Class.new(ExampleGroupDouble).describe(15)
+          example = group.new(ExampleProxy.new)
+          example.subject.should == 15
+        end
+      end
+
+    end
+
+    describe "explicit subject" do
+      describe "defined in a top level group" do
+        it "replaces the implicit subject in that group" do
+          group = Class.new(ExampleGroupDouble).describe(Array)
+          group.subject { [1,2,3] }
+          example = group.new(ExampleProxy.new)
+          example.subject.should == [1,2,3]
+        end
+      end
+
+      describe "defined in a top level group" do
+        it "is available in a nested group (subclass)" do
+          klass = Class.new do
+            extend  Spec::Example::Subject::ExampleGroupMethods
+            include Spec::Example::Subject::ExampleMethods
+            class << self
+              def described_class
+                Array
+              end
+            end
+            def described_class
+              self.class.described_class
+            end
+
+            subject {
+              [1,2,3]
+            }
+          end
+
+          subclass = Class.new(klass)
+
+          object = subclass.new
+          object.subject.should == [1,2,3]
+        end
+      end
+    end
+  end
+end