Legacy XML reports should preserve new line characters in message attributes

[gtach2o]

Hello!

After switching test execution from using gradle with junit platform to console launcher I noticed that
value of message attribute in JUnit xml report loosing new line characters.
e.g.
Using gradle xml :

<error message="line 1&#10; line 2&#10; line 3&#10;"...

Using Console launcher xml:

<error message="
line 1
line 2
line 3
"

Steps to reproduce

1. Run tests using gradle with junit platform. Throw multiline exception in test.
2. Run tests using console launcher, throw multiline exception in test.

Context

org.junit.platform:junit-platform-console-standalone:1.11.3
org.junit.jupiter:junit-jupiter-engine:5.11.3
JRE 23

As I understand console launcher uses new open/xml report generator and gradle platform launcher uses legacy report generator, right?

[marcphilipp]

@gtach2o I'm not sure what you mean. In your example, there are newline characters in the attribute value. While Gradle seems to replace \n using 
, the Console Launcher includes them as-is. This is well-formed XML. Does it cause any issues downstream?

[gtach2o]

@gtach2o I'm not sure what you mean. In your example, there are newline characters in the attribute value. While Gradle seems to replace \n using 
, the Console Launcher includes them as-is. This is well-formed XML. Does it cause any issues downstream?

Well, that xml is processed by some other services and message value extracted with javax.xml.bind.annotation.XmlAttribute and stored in DB, to be later shown on html dashboard.
There is no problem with tests executed with gradle and their message is displayed correctly in the browser, with newlines. The message from tests executed with the console launcher does not displayed with line breaks. It's just one long string because there is no \n in the original value.

While Gradle seems to replace \n using 


Can console launcher do this as well?

[marcphilipp]

I've looked into it in #4180. However, the closest I can get with the current STaX-based infrastructure is this:

<failure message="line 1&amp;#10; line 2">...</failure>

That's because when passing "line 1
 line 2" to javax.xml.stream.XMLStreamWriter#writeAttribute(String, String) it will replace all & characters with &.

@gtach2o Could you please check whether that kind of "double-escaping" works with your XmlAttribute-based processing?

[gtach2o]

That's because when passing "line 1
 line 2" to javax.xml.stream.XMLStreamWriter#writeAttribute(String, String) it will replace all & characters with &.

I think we only need to replace \n with 
.
Thrown exception (error or failure) contains \n not 
 (it is usually just a text with a stacktrace) after processing with XMLStreamWriter xml will have

<failure message="line 1&#10; line 2&#10;">...</failure>

One more note: if message contains quotes " they already escaped with " so there is some escaping mechanism applied. Just need add 
 for \n

[gtach2o]

How gradle with

test {
    useJUnitPlatform()
}

does it?

[gtach2o]

Maybe some double-escape avoiding mechanism can be applied

String escapeXmlAttribute(String input) {
        StringBuilder result = new StringBuilder();
        int length = input.length();
        for (int i = 0; i < length; i++) {
            char c = input.charAt(i);
            if (c == '&' && input.startsWith("&#10;", i)) {
               result.append("&#10;");
                i += 4;
            } else if (c == '\n') {
              result.append("&#10;");
            } else {                

result.append(StringEscapeUtils.escapeXml10(String.valueOf(c)));
            }
        }
        return result.toString();
}

or something like that, but to not reinvent the wheel would be better to look up how it s done during useJUnitPlatform()

[marcphilipp]

I did some more digging. The problem is that the default implementation of XMLStreamWriter does not replace \n, \r, and \t in attribute values while it does do so for "/' and &. I haven't found a way to customize that behavior.

However, adding Woodstox to the classpath fixes the problem since it does escape those characters by default. It would even allow to configure a custom escaping strategy since it's STaX2-compatible but we don't need that.

I don't think we should add Woodstox as a dependency to junit-platform-reporting, though. Doing so could affect the code under test which would suddenly use a different XML parser/writer implementation. Thus, I've added test coverage and documentation in #4184.

@gtach2o Could you please verify that adding Woodstox to your test runtime classpath solves the problem for you as well?

[marcphilipp]

How gradle with

test {
useJUnitPlatform()
}

does it?

FWIW, Gradle uses its own XML writer.

[gtach2o]

@gtach2o Could you please verify that adding Woodstox to your test runtime classpath solves the problem for you as well?

There is no way to do it without adding third party dependency ?

[gtach2o]

Can you create a custom wrapper class around XMLStreamWriter that overrides the writeAttribute method to handle escaping these characters? The rest of methods can use the original writer.

public class CustomXMLStreamWriter implements XMLStreamWriter {
    private final XMLStreamWriter delegate;

    public CustomXMLStreamWriter(XMLStreamWriter delegate) {
        this.delegate = delegate;
}

@Override
    public void writeAttribute(String localName, String value) throws XMLStreamException {
       
        String escapedValue = value
            .replace("\n", "
")
            .replace("\r", "
")
            .replace("\t", "	");
        delegate.writeAttribute(localName, escapedValue);
}
. . .

Then use it in legacy.xml.XmlReportWriter

      XMLStreamWriter xmlWriter = new CustomXMLStreamWriter(factory.createXMLStreamWriter(out)); 

Maybe this and no need in woodstox?

[marcphilipp]

No, that wouldn't help since the delegate would then escape & so we'd end up with 
.

But maybe I can wrap the underlying Writer and replace them there. I'll give that a try.

[marcphilipp]

Seems to work:

• Escape whitespace chars in XML attribute values #4186

[gtach2o]

Seems to work:

* [Escape whitespace chars in XML attribute values #4186](https://github.com/junit-team/junit5/pull/4186)

Cool!
So, woodstox is there only for tests?
Are there jar files somewhere I can download to try it out?

[marcphilipp]

Yes, Woodstox is only used for testing (as an additional test task).

I've now merged the PR and you can consume 5.12.0-SNAPSHOT versions from https://oss.sonatype.org/content/repositories/snapshots/

[gtach2o]

@marcphilipp Thank you! It works as expected! I presume 5.12 will be released in ~Feb 2025 ?

[marcphilipp]

We will include this in 5.11.4 which will be released toward the end of this week.