5 files changed, 136 insertions, 0 deletions
diff --git a/spec/support/data_modifier.rb b/spec/support/data_modifier.rb
new file mode 100644
index 000000000..7fb0db6f6
--- /dev/null
+++ b/spec/support/data_modifier.rb
@@ -0,0 +1,51 @@
+require_relative 'data_modifier/enum'
+module Support
+  module DataModifier
+    module InstanceMethods
+      CannotModify = Class.new RuntimeError
+
+      def advance_values(atts, *keys)
+        keys.inject(atts){ |h, k| h.merge( k => atts[k].next) }
+      end
+
+      # return array of atts wich each value modified, unboxing
+      # values if needed
+      def modify_atts(base_atts)
+        base_atts.keys.map do | key |
+          modify_att base_atts, key
+        end.compact
+      end
+
+      private
+      def modify_att atts, key
+        atts.merge(key => modify_value(atts[key]))
+      rescue CannotModify
+        nil
+      end
+      def modify_value value
+        case value
+        when String
+          "#{value}."
+        when Fixnum
+          value + 1
+        when TrueClass
+          false
+        when FalseClass
+          true
+        when Float
+          value * 1.1
+        when Date
+          value + 1.day
+        when Box
+          value.next.value
+        else
+          raise CannotModify
+        end
+      end
+    end
+  end
+end
+
+RSpec.configure do | c |
+  c.include Support::DataModifier::InstanceMethods, type: :checksum
+end
diff --git a/spec/support/data_modifier/bool.rb b/spec/support/data_modifier/bool.rb
new file mode 100644
index 000000000..f4be9bd89
--- /dev/null
+++ b/spec/support/data_modifier/bool.rb
@@ -0,0 +1,18 @@
+require_relative 'box'
+
+module Support
+    module DataModifier
+
+      class BoolBox
+        include Box
+        attr_reader :value
+
+        def initialize value
+          @value  = value
+        end
+        def next
+          self.class.new(!value)
+        end
+      end
+    end
+end
diff --git a/spec/support/data_modifier/box.rb b/spec/support/data_modifier/box.rb
new file mode 100644
index 000000000..0fb95f743
--- /dev/null
+++ b/spec/support/data_modifier/box.rb
@@ -0,0 +1,22 @@
+module Support
+  module DataModifier
+    module Box
+      def next
+        raise "Need to implement #{__method__} in #{self.class}"
+      end
+
+      class << self
+        def unbox atts
+          atts.inject Hash.new do | h, (k,v) |
+            h.merge(k => value_of(v))
+          end
+        end
+        def value_of v
+          self === v ? v.value : v
+        end
+      end
+    end
+
+  end
+end
+
diff --git a/spec/support/data_modifier/enum.rb b/spec/support/data_modifier/enum.rb
new file mode 100644
index 000000000..c8a6fe573
--- /dev/null
+++ b/spec/support/data_modifier/enum.rb
@@ -0,0 +1,19 @@
+require_relative 'box'
+
+module Support
+    module DataModifier
+
+      class EnumBox
+        include Box
+        attr_reader :value, :values
+
+        def initialize *enum_values
+          @values = enum_values
+          @value  = @values.first
+        end
+        def next
+          self.class.new(*(@values[1..-1] << @values.first))
+        end
+      end
+    end
+end
diff --git a/spec/support/random.rb b/spec/support/random.rb
new file mode 100644
index 000000000..f0168b9ef
--- /dev/null
+++ b/spec/support/random.rb
@@ -0,0 +1,26 @@
+module Support
+  module Random
+
+    PRETTY_LARGE_INT = 1 << 30 
+
+    def random_hex
+      SecureRandom.hex
+    end
+
+    def random_int
+      (random_number * PRETTY_LARGE_INT).to_i
+    end
+
+    def random_number
+      SecureRandom.random_number
+    end
+
+    def random_string
+      SecureRandom.urlsafe_base64
+    end
+  end
+end
+
+RSpec.configure do | c |
+  c.include Support::Random
+end