Added support for sequences

README

@@ -71,6 +71,23 @@ When using the association method, the same build strategy (build, create, or at
   post.new_record?       # => true
   post.author.new_record # => true
 
+== Sequences
+
+Unique values in a specific format (for example, e-mail addresses) can be
+generated using sequences. Sequences are defined by calling Factory.sequence,
+and values in a sequence are generated by calling Factory.next:
+
+  # Defines a new sequence
+  Factory.sequence :email do |n|
+    "person#{n}@example.com"
+  end
+
+  Factory.next :email
+  # => "person1@example.com"
+
+  Factory.next :email
+  # => "person2@example.com"
+
 == Using factories
 
   # Build and save a User instance

lib/factory_girl.rb

@@ -1,6 +1,7 @@
 require 'activesupport'
 require 'factory_girl/factory'
 require 'factory_girl/attribute_proxy'
+require 'factory_girl/sequence'
 
 # Shortcut for Factory.create.
 #

lib/factory_girl/factory.rb

@@ -1,7 +1,8 @@
 class Factory
 
-  cattr_accessor :factories #:nodoc:
+  cattr_accessor :factories, :sequences #:nodoc:
   self.factories = {}
+  self.sequences = {}
 
   attr_reader :name
 
@@ -24,6 +25,41 @@ class Factory
     self.factories[name] = instance
   end
 
+  # Defines a new sequence that can be used to generate unique values in a specific format.
+  #
+  # Arguments:
+  #   name: (Symbol)
+  #     A unique name for this sequence. This name will be referenced when
+  #     calling next to generate new values from this sequence.
+  #   block: (Proc)
+  #     The code to generate each value in the sequence. This block will be
+  #     called with a unique number each time a value in the sequence is to be
+  #     generated. The block should return the generated value for the
+  #     sequence.
+  #
+  # Example:
+  #   
+  #   Factory.sequence(:email) {|n| "somebody_#{n}@example.com" }
+  def self.sequence (name, &block)
+    self.sequences[name] = Sequence.new(&block)
+  end
+
+  # Generates and returns the next value in a sequence.
+  #
+  # Arguments:
+  #   name: (Symbol)
+  #     The name of the sequence that a value should be generated for.
+  #
+  # Returns:
+  #   The next value in the sequence. (Object)
+  def self.next (sequence)
+    unless self.sequences.key?(sequence)
+      raise "No such sequence: #{sequence}"
+    end
+
+    self.sequences[sequence].next
+  end
+
   def build_class #:nodoc:
     @build_class ||= @options[:class] || name.to_s.classify.constantize
   end

lib/factory_girl/sequence.rb

@@ -0,0 +1,17 @@
+class Factory
+
+  class Sequence
+
+    def initialize (&proc)
+      @proc  = proc
+      @value = 0
+    end
+
+    def next
+      @value += 1
+      @proc.call(@value)
+    end
+
+  end
+
+end

test/factory_test.rb

@@ -52,6 +52,28 @@ class FactoryTest < Test::Unit::TestCase
 
   end
 
+  context "defining a sequence" do
+
+    setup do
+      @sequence = mock('sequence')
+      @name     = :count
+      Factory::Sequence.stubs(:new).returns(@sequence)
+    end
+
+    should "create a new sequence" do
+      Factory::Sequence.expects(:new).with().returns(@sequence)
+      Factory.sequence(@name)
+    end
+
+    should "use the supplied block as the sequence generator" do
+      Factory::Sequence.stubs(:new).yields(1)
+      yielded = false
+      Factory.sequence(@name) {|n| yielded = true }
+      assert yielded
+    end
+
+  end
+
   context "a factory" do
 
     setup do
@@ -283,4 +305,29 @@ class FactoryTest < Test::Unit::TestCase
 
   end
 
+  context "after defining a sequence" do
+
+    setup do
+      @sequence = mock('sequence')
+      @name     = :test
+      @value    = '1 2 5'
+
+      @sequence.        stubs(:next).returns(@value)
+      Factory::Sequence.stubs(:new). returns(@sequence)
+
+      Factory.sequence(@name) {}
+    end
+
+    should "call next on the sequence when sent next" do
+      @sequence.expects(:next)
+
+      Factory.next(@name)
+    end
+
+    should "return the value from the sequence" do
+      assert_equal @value, Factory.next(@name)
+    end
+
+  end
+
 end

test/integration_test.rb

@@ -19,7 +19,11 @@ class IntegrationTest < Test::Unit::TestCase
       f.first_name 'Ben'
       f.last_name  'Stein'
       f.admin       true
-      f.email {|a| "#{a.first_name}.#{a.last_name}@example.com".downcase }
+      f.email { Factory.next(:email) }
+    end
+
+    Factory.sequence :email do |n|
+      "somebody#{n}@example.com"
     end
   end
 
@@ -108,4 +112,32 @@ class IntegrationTest < Test::Unit::TestCase
 
   end
 
+  context "an attribute generated by a sequence" do
+
+    setup do
+      @email = Factory.attributes_for(:admin)[:email]
+    end
+
+    should "match the correct format" do
+      assert_match /^somebody\d+@example\.com$/, @email
+    end
+
+    context "after the attribute has already been generated once" do
+
+      setup do
+        @another_email = Factory.attributes_for(:admin)[:email]
+      end
+
+      should "match the correct format" do
+        assert_match /^somebody\d+@example\.com$/, @email
+      end
+
+      should "not be the same as the first generated value" do
+        assert_not_equal @email, @another_email
+      end
+
+    end
+
+  end
+
 end

test/sequence_test.rb

@@ -0,0 +1,29 @@
+require(File.join(File.dirname(__FILE__), 'test_helper'))
+
+class SequenceTest < Test::Unit::TestCase
+
+  context "a sequence" do
+
+    setup do
+      @sequence = Factory::Sequence.new {|n| "=#{n}" }
+    end
+
+    should "start with a value of 1" do
+      assert_equal "=1", @sequence.next
+    end
+
+    context "after being called" do
+
+      setup do
+        @sequence.next
+      end
+
+      should "use the next value" do
+        assert_equal "=2", @sequence.next
+      end
+
+    end
+
+  end
+
+end