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/unit/file_system_unit_test.rb

@@ -0,0 +1,35 @@
+require 'test_helper'
+
+class FileSystemUnitTest < Test::Unit::TestCase
+  include Liquid
+
+  def test_default
+    assert_raise(FileSystemError) do
+      BlankFileSystem.new.read_template_file("dummy", {'dummy'=>'smarty'})
+    end
+  end
+
+  def test_local
+    file_system = Liquid::LocalFileSystem.new("/some/path")
+    assert_equal "/some/path/_mypartial.liquid"    , file_system.full_path("mypartial")
+    assert_equal "/some/path/dir/_mypartial.liquid", file_system.full_path("dir/mypartial")
+
+    assert_raise(FileSystemError) do
+      file_system.full_path("../dir/mypartial")
+    end
+
+    assert_raise(FileSystemError) do
+      file_system.full_path("/dir/../../dir/mypartial")
+    end
+
+    assert_raise(FileSystemError) do
+      file_system.full_path("/etc/passwd")
+    end
+  end
+
+  def test_custom_template_filename_patterns
+    file_system = Liquid::LocalFileSystem.new("/some/path", "%s.html")
+    assert_equal "/some/path/mypartial.html"    , file_system.full_path("mypartial")
+    assert_equal "/some/path/dir/mypartial.html", file_system.full_path("dir/mypartial")
+  end
+end # FileSystemTest