Make sure serializing axlsx packages with identical contents always results in identical zip files.

This improves the possibilites for caching and/or consolidating the generated zip (xlsx) files.

Up to now, serializing the same package at different times resulted in different zip files because of the timestamp in the zip entry metadata.

Note: To generate identical packages (and thus identical zip files), you'll have set Core#created explicitly, eg. with `Package.new(created_at: Time.local(2013, 1, 1)`.

2 files changed, 11 insertions, 0 deletions

diff --git a/test/tc_helper.rb b/test/tc_helper.rb
index 08dec0b3..af40a1e4 100644
--- a/test/tc_helper.rb
+++ b/test/tc_helper.rb
@@ -6,4 +6,5 @@ SimpleCov.start do
 end
 
 require 'test/unit'
+require "timecop"
 require "axlsx.rb"
diff --git a/test/tc_package.rb b/test/tc_package.rb
index df096a31..86f11dd4 100644
--- a/test/tc_package.rb
+++ b/test/tc_package.rb
@@ -123,6 +123,16 @@ class TestPackage < Test::Unit::TestCase
       end
     end
   end
+  
+  # See comment for Package#zip_entry_for_part
+  def test_serialization_creates_identical_files_at_any_time_if_created_at_is_set
+    @package.core.created = Time.now
+    zip_content_now = @package.to_stream.string
+    Timecop.travel(3600) do
+      zip_content_then = @package.to_stream.string
+      assert zip_content_then == zip_content_now, "zip files are not identical"
+    end
+  end
 
   def test_validation
     assert_equal(@package.validate.size, 0, @package.validate)