Add Document#write_to_string for easily writing the document to a string

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 * [HexaPDF::Task::MergeAcroForm] for merging AcroForm information for imported
   pages
+* [HexaPDF::Document#write_to_string] for easily writing a document to a String
 
 ### Changed
 

lib/hexapdf/document.rb

@@ -786,6 +786,15 @@ def write(file_or_io, incremental: false, validate: true, update_fields: true, o
       end
     end
 
+    # Writes the document to a string and returns the string.
+    #
+    # See #write for further information and details on the available arguments.
+    def write_to_string(**args)
+      io = StringIO.new(''.b)
+      write(io)
+      io.string
+    end
+
     def inspect #:nodoc:
       "<#{self.class.name}:#{object_id}>"
     end

test/hexapdf/test_document.rb

@@ -595,4 +595,13 @@
       refute(dupped.encrypted?)
     end
   end
+
+  it "writes the document to a string" do
+    doc = HexaPDF::Document.new
+    doc.trailer.info[:test] = :test
+    str = doc.write_to_string(update_fields: false)
+    assert_equal(Encoding::ASCII_8BIT, str.encoding)
+    doc = HexaPDF::Document.new(io: StringIO.new(str))
+    assert_equal(:test, doc.trailer.info[:test])
+  end
 end