Redmine

It seems that the line break code is different between preview mode and non-preview mode.
So preview mode doesn't seem to match the regular expression ApplicationHelper::MACROS_RE.

preview mode(Linebreak: "\n"). Since the input value is posted via JavaScript, the line break code is replaced from "\r\n" to "\n".

"Test code for the bug in Redmine 4.x\n\n{{collapse(Collapse 1)}}\n\nAbove is a empty collapse macro which renders correctly in preview and in wiki view.\n\n{{collapse(Collapse 2)\n}}\n\nAbove is a empty collapse macro which renders correctly in wiki view but this text (and the following macro up to its closing curly brackets) will not be visible in preview mode.\n\n{{collapse(Collapse 3)\nThis is a block of text that is collapsed by default.\nIt can be expanded by clicking a link.\n}}\n\nAbove is a non empty collapse macro which renders correctly in preview and in wiki view." 

non-preview mode(Linebreak: "\r\n")

"Test code for the bug in Redmine 4.x\r\n\r\n{{collapse(Collapse 1)}}\r\n\r\nAbove is a empty collapse macro which renders correctly in preview and in wiki view.\r\n\r\n{{collapse(Collapse 2)\r\n}}\r\n\r\nAbove is a empty collapse macro which renders correctly in wiki view but this text (and the following macro up to its closing curly brackets) will not be visible in preview mode.\r\n\r\n{{collapse(Collapse 3)\r\nThis is a block of text that is collapsed by default.\r\nIt can be expanded by clicking a link.\r\n}}\r\n\r\nAbove is a non empty collapse macro which renders correctly in preview and in wiki view." 

Fixed the regular expression. I think this will solve the problem.

diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index bf55e05a5..5bcdca29f 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -1277,8 +1277,8 @@ module ApplicationHelper
                 (
                 \{\{                        # opening tag
                 ([\w]+)                     # macro name
-                (\(([^\n\r]*?)\))?          # optional arguments
-                ([\n\r].*?[\n\r])?          # optional block of text
+                (\(([^\R]*?)\))?            # optional arguments
+                (\R.*?\R?)?                 # optional block of text
                 \}\}                        # closing tag
                 )
                )/mx unless const_defined?(:MACROS_RE)

Go MAEDA wrote:

I think the following line does not work as expected because the metacharacter \R cannot be put into []. [^\R] is actually equivalent to [^R].

[...]

See the test result below.

[...]

Thank you for your report.
I confirmed that the negative match /[^\R]/ doesn't work with the line break code.
Fixed the patch.

Attaching test code for the patch.

Setting the target version to 4.0.8.

The actual cause of the problem is that the regular expression expects that there are two line terminators between "macroname{{" and "}}". The reason why there appears to be no problem when a line terminator is "\r\n" is that "\r" is parsed as the first line terminator and "\n" is parsed as the second line terminator.

So, even after applying the patch 33432-v2.patch, the macro in the following text is not detected in the Preview tab.

collapse{{
}}

The code below can test it.

Index: test/helpers/application_helper_test.rb
===================================================================
--- test/helpers/application_helper_test.rb    (リビジョン 19814)
+++ test/helpers/application_helper_test.rb    (作業コピー)
@@ -1937,6 +1937,13 @@
     end
   end

+  def test_catch_macros_should_allow_empty_text_block
+    macros = catch_macros(+"{{collapse\r\n}}")
+    assert_equal "{{collapse\r\n}}", macros[0]
+    macros = catch_macros(+"{{collapse\n}}")
+    assert_equal "{{collapse\n}}", macros[0]
+  end
+
   private

   def wiki_links_with_special_characters