Seperate unit and integration tests.

This makes it easier to re-use the integration tests in a seperate gem that
optimizes parts of liquid with a native implementation.

test/integration/context_test.rb

@@ -0,0 +1,24 @@
+require 'test_helper'
+
+class ContextTest < Test::Unit::TestCase
+  include Liquid
+
+  def test_override_global_filter
+    global = Module.new do
+      def notice(output)
+        "Global #{output}"
+      end
+    end
+
+    local = Module.new do
+      def notice(output)
+        "Local #{output}"
+      end
+    end
+
+    Template.register_filter(global)
+    assert_equal 'Global test', Template.parse("{{'test' | notice }}").render!
+    assert_equal 'Local test', Template.parse("{{'test' | notice }}").render!({}, :filters => [local])
+  end
+
+end