Merge pull request #541 from rspec/issue-529

Correct stub undefined parent modules all the way down when stubbing a nested constant.

Changelog.md

@@ -43,6 +43,8 @@ Bug Fixes:
 * Fix regression in `stub_chain`/`receive_message_chain` that caused
   it to raise an `ArgumentError` when passing args to the stubbed
   methods. (Sam Phippen)
+* Correct stub of undefined parent modules all the way down when stubbing a
+  nested constant. (Xavier Shay)
 
 Enhancements:
 

lib/rspec/mocks/mutate_const.rb

@@ -322,19 +322,15 @@ def verify_constants_to_transfer!
       # @api private
       class UndefinedConstantSetter < BaseMutator
         def mutate
-          remaining_parts = @context_parts.dup
-          @deepest_defined_const = @context_parts.inject(Object) do |klass, name|
-            break klass unless const_defined_on?(klass, name)
-            remaining_parts.shift
-            get_const_defined_on(klass, name)
-          end
-
-          context = remaining_parts.inject(@deepest_defined_const) do |klass, name|
-            klass.const_set(name, Module.new)
+          @parent = @context_parts.inject(Object) do |klass, name|
+            if const_defined_on?(klass, name)
+              get_const_defined_on(klass, name)
+            else
+              ConstantMutator.stub(name_for(klass, name), Module.new)
+            end
           end
 
-          @const_to_remove = remaining_parts.first || @const_name
-          context.const_set(@const_name, @mutated_value)
+          @parent.const_set(@const_name, @mutated_value)
         end
 
         def to_constant
@@ -346,7 +342,18 @@ def to_constant
         end
 
         def reset
-          @deepest_defined_const.__send__(:remove_const, @const_to_remove)
+          @parent.__send__(:remove_const, @const_name)
+        end
+
+      private
+
+        def name_for(parent, name)
+          root = if parent == Object
+            ''
+          else
+            parent.name
+          end
+          root + '::' + name
         end
       end
 

spec/rspec/mocks/mutate_const_spec.rb

@@ -451,6 +451,18 @@ def change_const_value_to(value)
           it("returns nil for the original value")      { expect(const.original_value).to be_nil }
         end
 
+        context 'for a previously undefined parent of a stubbed constant' do
+          before { stub_const("TestClass::UndefinedModule::Undefined", :other) }
+          let(:const) { Constant.original("TestClass::UndefinedModule") }
+
+          it("exposes its name")                        { expect(const.name).to eq("TestClass::UndefinedModule") }
+          it("indicates it was not previously defined") { expect(const).not_to be_previously_defined }
+          it("indicates it has been mutated")           { expect(const).to be_mutated }
+          it("indicates it has been stubbed")           { expect(const).to be_stubbed }
+          it("indicates it has not been hidden")        { expect(const).not_to be_hidden }
+          it("returns nil for the original value")      { expect(const.original_value).to be_nil }
+        end
+
         context 'for a previously undefined unstubbed constant' do
           let(:const) { Constant.original("TestClass::Undefined") }
 

spec/rspec/mocks/verifying_double_spec.rb

@@ -84,6 +84,13 @@ module Mocks
             expect(o.undefined_instance_method(:arg)).to eq(true)
           end
 
+          it 'handles classes that are materialized after mocking' do
+            stub_const "A::B", Object.new
+            o = instance_double "A", :undefined_instance_method => true
+
+            expect(o.undefined_instance_method).to eq(true)
+          end
+
           context 'for null objects' do
             let(:o) { instance_double('NonLoadedClass').as_null_object }