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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".
<pre><code class="ruby">
"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."
</code></pre>

non-preview mode(Linebreak: "\r\n")
<pre><code class="ruby">
"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."
</code></pre>

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

<pre><code class="diff">
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)
</code></pre>
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Yuichi HARADA wrote:
> 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@.

Thank you for posting the patch. But I think the patch needs some fix.

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

<pre><code class="ruby">
(\(([^\R]*?)\))? # optional arguments
</code></pre>

See the test result below.

<pre>
irb(main):001:0> /[^\n\r]/ =~ "\n"
=> nil
irb(main):002:0> /[^\R]/ =~ "\n"
=> 0
irb(main):003:0> /[^\R]/ =~ "R"
=> nil
</pre>
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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 attachment:33432-v2.patch, the macro in the following text is not detected in the Preview tab.

<pre>
collapse{{
}}
</pre>

The code below can test it.

<pre><code class="diff">
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
</code></pre>
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