return Signature instance from #sign

lib/minisign/private_key.rb

@@ -65,13 +65,13 @@ def sign(filename, message, comment = nil)
       signature = ed25519_signing_key.sign(blake2b512(message))
       trusted_comment = comment || "timestamp:#{Time.now.to_i}\tfile:#{filename}\thashed"
       global_signature = ed25519_signing_key.sign("#{signature}#{trusted_comment}")
-      [
+      Minisign::Signature.new([
         'untrusted comment: <arbitrary text>',
         Base64.strict_encode64("ED#{@key_id.pack('C*')}#{signature}"),
         "trusted comment: #{trusted_comment}",
         Base64.strict_encode64(global_signature),
         ''
-      ].join("\n")
+      ].join("\n"))
     end
 
     def to_s

lib/minisign/signature.rb

@@ -36,7 +36,7 @@ def signature
     end
 
     def to_s
-      @lines.join("\n") + "\n"
+      "#{@lines.join("\n")}\n"
     end
 
     private

spec/minisign/private_key_spec.rb

@@ -89,9 +89,8 @@
       File.write("test/generated/#{@filename}", @message)
       signature = @private_key.sign(@filename, @message, 'this is a trusted comment')
       File.write("test/generated/#{@filename}.minisig", signature)
-      @signature = Minisign::Signature.new(signature)
       @public_key = Minisign::PublicKey.new('RWSmKaOrT6m3TGwjwBovgOmlhSbyBUw3hyhnSOYruHXbJa36xHr8rq2M')
-      expect(@public_key.verify(@signature, @message)).to match('Signature and comment signature verified')
+      expect(@public_key.verify(signature, @message)).to match('Signature and comment signature verified')
     end
     it 'signs a file with an unencrypted key' do
       @filename = 'unencrypted-key.txt'
@@ -100,9 +99,8 @@
       @unencrypted_private_key = Minisign::PrivateKey.new(File.read('test/unencrypted.key'))
       signature = @unencrypted_private_key.sign(@filename, @message)
       File.write("test/generated/#{@filename}.minisig", signature)
-      @signature = Minisign::Signature.new(signature)
       @public_key = Minisign::PublicKey.new('RWT/N/MXaBIWRAPzfdEKqVRq9txskjf5qh7EbqMLVHjkNTGFazO3zMw2')
-      expect(@public_key.verify(@signature, @message)).to match('Signature and comment signature verified')
+      expect(@public_key.verify(signature, @message)).to match('Signature and comment signature verified')
     end
   end
 end