adding AR::Fixtures::File class to wrap a fixture file

activerecord/lib/active_record/fixtures.rb

@@ -14,6 +14,7 @@
 require 'active_support/core_ext/logger'
 require 'active_support/ordered_hash'
 require 'active_support/core_ext/module/deprecation'
+require 'active_record/fixtures/file'
 
 if defined? ActiveRecord
   class FixtureClassNotFound < ActiveRecord::ActiveRecordError #:nodoc:

activerecord/lib/active_record/fixtures/file.rb

+begin
+  require 'psych'
+rescue LoadError
+end
+
+require 'erb'
+require 'yaml'
+
+module ActiveRecord
+  class Fixtures
+    class File
+      include Enumerable
+
+      ##
+      # Open a fixture file named +file+.  When called with a block, the block
+      # is called with the filehandle and the filehandle is automatically closed
+      # when the block finishes.
+      def self.open(file)
+        x = new file
+        block_given? ? yield(x) : x
+      end
+
+      def initialize(file)
+        @file = file
+        @rows = nil
+      end
+
+      def each(&block)
+        rows.each(&block)
+      end
+
+      private
+      def rows
+        return @rows if @rows
+        @rows = YAML.load(render(IO.read(@file))).to_a
+      end
+
+      def render(content)
+        ERB.new(content).result
+      end
+    end
+  end
+end

activerecord/test/cases/fixtures/file_test.rb

+require "cases/helper"
+require 'tempfile'
+
+module ActiveRecord
+  class Fixtures
+    class FileTest < ActiveRecord::TestCase
+      def test_open
+        fh = File.open(::File.join(FIXTURES_ROOT, "accounts.yml"))
+        assert_equal 6, fh.to_a.length
+      end
+
+      def test_open_with_block
+        called = false
+        File.open(::File.join(FIXTURES_ROOT, "accounts.yml")) do |fh|
+          called = true
+          assert_equal 6, fh.to_a.length
+        end
+        assert called, 'block called'
+      end
+
+      def test_names
+        File.open(::File.join(FIXTURES_ROOT, "accounts.yml")) do |fh|
+          assert_equal ["signals37",
+                        "unknown",
+                        "rails_core_account",
+                        "last_account",
+                        "rails_core_account_2",
+                        "odegy_account"], fh.to_a.map(&:first)
+        end
+      end
+
+      def test_values
+        File.open(::File.join(FIXTURES_ROOT, "accounts.yml")) do |fh|
+          assert_equal [1,2,3,4,5,6], fh.to_a.map(&:last).map { |x| x['id'] }
+        end
+      end
+
+      def test_erb_processing
+        File.open(::File.join(FIXTURES_ROOT, "developers.yml")) do |fh|
+          devs = Array.new(8) { |i| "dev_#{i + 3}" }
+          assert_equal [], devs - fh.to_a.map(&:first)
+        end
+      end
+    end
+  end
+end