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/assign_test.rb

@@ -0,0 +1,27 @@
+require 'test_helper'
+
+class AssignTest < Test::Unit::TestCase
+  include Liquid
+
+  def test_assigned_variable
+    assert_template_result('.foo.',
+                           '{% assign foo = values %}.{{ foo[0] }}.',
+                           'values' => %w{foo bar baz})
+
+    assert_template_result('.bar.',
+                           '{% assign foo = values %}.{{ foo[1] }}.',
+                           'values' => %w{foo bar baz})
+  end
+
+  def test_assign_with_filter
+    assert_template_result('.bar.',
+                           '{% assign foo = values | split: "," %}.{{ foo[1] }}.',
+                           'values' => "foo,bar,baz")
+  end
+
+  def test_assign_syntax_error
+    assert_match_syntax_error(/assign/,
+                       '{% assign foo not values %}.',
+                       'values' => "foo,bar,baz")
+  end
+end # AssignTest