added intersection specs

spec/unit/intersection_spec.rb

@@ -0,0 +1,42 @@
+#
+#  Copyright (c) 2011, SoundCloud Ltd., Rany Keddo, Tobias Bielohlawek, Tobias
+#  Schmidt
+#
+
+require File.expand_path(File.dirname(__FILE__)) + '/unit_helper'
+
+require 'lhm/table'
+require 'lhm/migrator'
+
+describe Lhm::Intersection do
+  include UnitHelper
+
+  it "should not have dropped changes" do
+    origin = Lhm::Table.new("origin")
+    origin.columns["dropped"]  = varchar
+    origin.columns["retained"] = varchar
+
+    destination = Lhm::Table.new("destination")
+    destination.columns["retained"] = varchar
+
+    intersection = Lhm::Intersection.new(origin, destination)
+    intersection.common.include?("dropped").must_equal(false)
+  end
+
+  it "should have unchanged columns" do
+    origin = Lhm::Table.new("origin")
+    origin.columns["dropped"]  = varchar
+    origin.columns["retained"] = varchar
+
+    destination = Lhm::Table.new("destination")
+    destination.columns["retained"] = varchar
+
+    intersection = Lhm::Intersection.new(origin, destination)
+    intersection.common.must_equal(["retained"])
+  end
+
+  def varchar
+    { :metadata => "VARCHAR(255)"}
+  end
+end
+