Assert how contents are zipped

Previously we tested that either rubyzip or shelling out to zip produced
the expected xlsx file, but we never explicitly checked whether rubyzip
or shell zip was used. I noticed that rubyzip always sets a far future
date, whereas `zip` uses today's date. I'm using this as a heuristic to
determine which zip method was used.

1 files changed, 18 insertions, 0 deletions

diff --git a/test/tc_package.rb b/test/tc_package.rb
index 628d20ae..fc48a9eb 100644
--- a/test/tc_package.rb
+++ b/test/tc_package.rb
@@ -129,12 +129,14 @@ class TestPackage < Test::Unit::TestCase
   def test_serialization
     @package.serialize(@fname)
     assert_zip_file_matches_package(@fname, @package)
+    assert_created_with_rubyzip(@fname, @package)
     File.delete(@fname)
   end
 
   def test_serialization_with_zip_command
     @package.serialize(@fname, zip_command: "zip")
     assert_zip_file_matches_package(@fname, @package)
+    assert_created_with_zip_command(@fname, @package)
     File.delete(@fname)
   end
 
@@ -142,6 +144,7 @@ class TestPackage < Test::Unit::TestCase
     fname = "#{Dir.tmpdir}/#{@fname}"
     @package.serialize(fname, zip_command: "zip")
     assert_zip_file_matches_package(fname, @package)
+    assert_created_with_zip_command(fname, @package)
     File.delete(fname)
   end
 
@@ -156,6 +159,21 @@ class TestPackage < Test::Unit::TestCase
     package.send(:parts).each{ |part| zf.get_entry(part[:entry]) }
   end
 
+  def assert_created_with_rubyzip(fname, package)
+    assert_equal 2098, get_mtime(fname, package).year, "XLSX files created with RubyZip have 2098 as the file mtime"
+  end
+
+  def assert_created_with_zip_command(fname, package)
+    assert_equal Time.now.utc.year, get_mtime(fname, package).year, "XLSX files created with a zip command have the current year as the file mtime"
+  end
+
+  def get_mtime(fname, package)
+    zf = Zip::File.open(fname)
+    part = package.send(:parts).first
+    entry = zf.get_entry(part[:entry])
+    entry.mtime.utc
+  end
+
   def test_serialization_with_deprecated_argument
     warnings = capture_warnings do
       @package.serialize(@fname, false)