Add tests for path traversal errors

test/test_git.rb

@@ -83,6 +83,12 @@ class TestGit < Test::Unit::TestCase
     assert_equal 'bar', @git.fs_read('foo')
   end
+  def test_fs_read_path_traversal
+    assert_raise RuntimeError do
+      @git.fs_read('../foo')
+    end
+  end
+
   def test_fs_write
     f = stub
     f.expects(:write).with('baz')
@@ -91,6 +97,12 @@ class TestGit < Test::Unit::TestCase
     @git.fs_write('foo/bar', 'baz')
   end
+  def test_fs_write_path_traversal
+    assert_raise RuntimeError do
+      @git.fs_read('../foo/bar')
+    end
+  end
+
   def test_fs_delete
     FileUtils.expects(:rm_rf).with(File.join(@git.git_dir, 'foo'))
     @git.fs_delete('foo')