add let()

Author: dchelimsky

lib/rspec/core/example.rb

@@ -57,15 +57,15 @@ def run_finished(status, results={})
       end
 
       def run_before_each
-        @behaviour_instance._setup_mocks if @behaviour_instance.respond_to?(:_setup_mocks)
-        @behaviour.eval_before_eachs(@behaviour_instance)
+        @example_group_instance._setup_mocks if @example_group_instance.respond_to?(:_setup_mocks)
+        @behaviour.eval_before_eachs(@example_group_instance)
       end
 
       def run_after_each
-        @behaviour.eval_after_eachs(@behaviour_instance)
-        @behaviour_instance._verify_mocks if @behaviour_instance.respond_to?(:_verify_mocks)
+        @behaviour.eval_after_eachs(@example_group_instance)
+        @example_group_instance._verify_mocks if @example_group_instance.respond_to?(:_verify_mocks)
       ensure
-        @behaviour_instance._teardown_mocks if @behaviour_instance.respond_to?(:_teardown_mocks)
+        @example_group_instance._teardown_mocks if @example_group_instance.respond_to?(:_teardown_mocks)
       end
 
       def assign_auto_description
@@ -75,9 +75,9 @@ def assign_auto_description
         end
       end
 
-      def run(behaviour_instance)
-        @behaviour_instance = behaviour_instance
-        @behaviour_instance.running_example = self
+      def run(example_group_instance)
+        @example_group_instance = example_group_instance.reset
+        @example_group_instance.running_example = self
 
         run_started
 
@@ -86,7 +86,7 @@ def run(behaviour_instance)
 
         begin
           run_before_each
-          @behaviour_instance.instance_eval(&example_block) if example_block
+          @example_group_instance.instance_eval(&example_block) if example_block
         rescue Exception => e
           exception_encountered = e
           all_systems_nominal = false
@@ -100,7 +100,7 @@ def run(behaviour_instance)
           exception_encountered ||= e
           all_systems_nominal = false
         ensure
-          @behaviour_instance.running_example = nil
+          @example_group_instance.running_example = nil
         end
 
         if exception_encountered

lib/rspec/core/example_group.rb

@@ -206,18 +206,23 @@ def self.eval_after_eachs(running_behaviour)
       end
 
       def self.run(reporter)
-        behaviour_instance = new
+        example_group_instance = new
         reporter.add_behaviour(self)
-        eval_before_alls(behaviour_instance)
-        success = run_examples(behaviour_instance, reporter)
-        eval_after_alls(behaviour_instance)
+        eval_before_alls(example_group_instance)
+        success = run_examples(example_group_instance, reporter)
+        eval_after_alls(example_group_instance)
 
         success
       end
 
       # Runs all examples, returning true only if all of them pass
-      def self.run_examples(behaviour_instance, reporter)
-        examples_to_run.map { |ex| ex.run(behaviour_instance) }.all?
+      def self.run_examples(example_group_instance, reporter)
+        examples_to_run.map { |ex| ex.run(example_group_instance) }.all?
+      end
+
+      def reset
+        assignments.clear
+        self
       end
 
       def self.subclass(base_name, &body) # :nodoc:
@@ -233,7 +238,17 @@ def self.subclass(base_name, &body) # :nodoc:
       def self.to_s
         self == Rspec::Core::ExampleGroup ? 'Rspec::Core::ExampleGroup' : name
       end
+
+      def assignments
+        @assignments ||= {}
+      end
 
+      def self.let(name, &block)
+        define_method name do
+          assignments[name] ||= instance_eval(&block)
+        end
+      end
+
     end
   end
 end

spec/rspec/core/example_group_spec.rb

@@ -1,6 +1,6 @@
 require 'spec_helper'
 
-def empty_behaviour_group(name='Empty ExampleGroup Group')
+def empty_example_group(name='Empty ExampleGroup Group')
   group = Rspec::Core::ExampleGroup.describe(Object, name) {}
   remove_last_describe_from_world
   yield group if block_given?
@@ -35,7 +35,7 @@ def empty_behaviour_group(name='Empty ExampleGroup Group')
 
       it "should be built correctly when nested" do
         behaviour_to_test = nil
-        group = empty_behaviour_group('test')
+        group = empty_example_group('test')
         group.name.should == 'Object test'
 
         nested_group_one = group.describe('nested one') { }
@@ -127,13 +127,13 @@ def empty_behaviour_group(name='Empty ExampleGroup Group')
     describe "adding before and after hooks" do
 
       it "should expose the before each blocks at before_eachs" do
-        group = empty_behaviour_group
+        group = empty_example_group
         group.before(:each) { 'foo' }
         group.should have(1).before_eachs
       end
 
       it "should maintain the before each block order" do
-        group = empty_behaviour_group 
+        group = empty_example_group 
         group.before(:each) { 15 }
         group.before(:each) { 'A' }
         group.before(:each) { 33.5 }
@@ -144,13 +144,13 @@ def empty_behaviour_group(name='Empty ExampleGroup Group')
       end
 
       it "should expose the before all blocks at before_alls" do
-        group = empty_behaviour_group
+        group = empty_example_group
         group.before(:all) { 'foo' }
         group.should have(1).before_alls
       end
 
       it "should maintain the before all block order" do
-        group = empty_behaviour_group 
+        group = empty_example_group 
         group.before(:all) { 15 }
         group.before(:all) { 'A' }
         group.before(:all) { 33.5 }
@@ -161,13 +161,13 @@ def empty_behaviour_group(name='Empty ExampleGroup Group')
       end
 
       it "should expose the after each blocks at after_eachs" do
-        group = empty_behaviour_group
+        group = empty_example_group
         group.after(:each) { 'foo' }
         group.should have(1).after_eachs
       end
 
       it "should maintain the after each block order" do
-        group = empty_behaviour_group 
+        group = empty_example_group 
         group.after(:each) { 15 }
         group.after(:each) { 'A' }
         group.after(:each) { 33.5 }
@@ -178,13 +178,13 @@ def empty_behaviour_group(name='Empty ExampleGroup Group')
       end
 
       it "should expose the after all blocks at after_alls" do
-        group = empty_behaviour_group
+        group = empty_example_group
         group.after(:all) { 'foo' }
         group.should have(1).after_alls
       end
 
       it "should maintain the after each block order" do
-        group = empty_behaviour_group 
+        group = empty_example_group 
         group.after(:all) { 15 }
         group.after(:all) { 'A' }
         group.after(:all) { 33.5 }
@@ -199,21 +199,21 @@ def empty_behaviour_group(name='Empty ExampleGroup Group')
     describe "adding examples" do
 
       it "should allow adding an example using 'it'" do
-        group = empty_behaviour_group
+        group = empty_example_group
         group.it("should do something") { }
         group.examples.size.should == 1
       end
 
       it "should expose all examples at examples" do
-        group = empty_behaviour_group
+        group = empty_example_group
         group.it("should do something 1") { }
         group.it("should do something 2") { }
         group.it("should do something 3") { }
         group.examples.size.should == 3
       end
 
       it "should maintain the example order" do
-        group = empty_behaviour_group
+        group = empty_example_group
         group.it("should 1") { }
         group.it("should 2") { }
         group.it("should 3") { }
@@ -350,4 +350,26 @@ def stub_behaviour
 
   end
 
+  describe "#let" do
+    let(:counter) do
+      Class.new do
+        def initialize
+          @count = 0
+        end
+        def count
+          @count += 1
+        end
+      end.new
+    end
+
+    it "generates an instance method" do
+      counter.count.should == 1
+    end
+
+    it "caches the value" do
+      counter.count.should == 1
+      counter.count.should == 2
+    end
+  end
+
 end