Do not store current timestamps in gz headers

lib/rdoc/generator/json_index.rb

@@ -147,12 +147,15 @@ def generate
 
       JSON.dump data, io, 0
     end
+    unless ENV['SOURCE_DATE_EPOCH'].nil?
+      index_file.utime index_file.atime, Time.at(ENV['SOURCE_DATE_EPOCH'].to_i).gmtime
+    end
 
     Dir.chdir @template_dir do
       Dir['**/*.js'].each do |source|
         dest = File.join out_dir, source
 
-        FileUtils.install source, dest, :mode => 0644, :verbose => $DEBUG_RDOC
+        FileUtils.install source, dest, :mode => 0644, :preserve => true, :verbose => $DEBUG_RDOC
       end
     end
   end

test/test_rdoc_generator_json_index.rb

@@ -8,7 +8,7 @@ class TestRDocGeneratorJsonIndex < RDoc::TestCase
   def setup
     super
 
-    @tmpdir = File.join Dir.tmpdir, "test_rdoc_generator_darkfish_#{$$}"
+    @tmpdir = Dir.mktmpdir "test_rdoc_generator_darkfish_#{$$}_"
     FileUtils.mkdir_p @tmpdir
 
     @options = RDoc::Options.new
@@ -89,12 +89,25 @@ def test_file_dir
   end
 
   def test_generate
+    now = Time.now
     @g.generate
 
     assert_file 'js/searcher.js'
     assert_file 'js/navigation.js'
     assert_file 'js/search_index.js'
 
+    orig_file = Pathname(File.join @pwd, 'lib/rdoc/generator/template/json_index/js/navigation.js')
+    generated_file = Pathname(File.join @tmpdir, 'js/navigation.js')
+
+    # This is dirty hack on JRuby for MiniTest 4
+    assert orig_file.mtime.inspect == generated_file.mtime.inspect,
+      '.js files should be tha same timestamp of original'
+
+    assert generated_file.mtime < now, '.js files should be the same timestamp'
+
+    generated_search_index = Pathname(File.join @tmpdir, 'js/search_index.js')
+    assert generated_search_index.mtime > (now - 1), 'search_index.js should be generated timestamp'
+
     json = File.read 'js/search_index.js'
 
     json =~ /\Avar search_data = /
@@ -137,6 +150,20 @@ def test_generate
     assert_equal expected, index
   end
 
+  def test_generate_search_index_with_reproducible_builds
+    backup_epoch = ENV['SOURCE_DATE_EPOCH']
+    ruby_birthday = Time.parse 'Wed, 24 Feb 1993 21:00:00 +0900'
+    ENV['SOURCE_DATE_EPOCH'] = ruby_birthday.to_i.to_s
+
+    @g.generate
+
+    assert_file 'js/search_index.js'
+    generated_search_index = Pathname(File.join @tmpdir, 'js/search_index.js')
+    assert_equal ruby_birthday, generated_search_index.mtime
+
+    ENV['SOURCE_DATE_EPOCH'] = backup_epoch
+  end
+
   def test_generate_gzipped
     begin
       require 'zlib'