[meganemura]

Description

The JUnit reporter strips ANSI sequences from the <failure> body, but not from attribute values. escapeXML removes the ESC byte because XML cannot hold it, but the rest of each sequence stays. An error message that has colors (for example, the DOM dump that Testing Library adds by default) gives:

<failure message="[36m&lt;body&gt;[39m" type="Error">

CI tools that show the message attribute then print [36m as text.

This PR strips ANSI sequences in escapeXML. The message attribute, the name of unhandled-error test cases, and system-out / system-err now get the same treatment as the <failure> body.

AI disclosure: I used Claude Code to investigate and write this change.

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Tests

• Run the tests with pnpm test:ci.

Locally, 8 tests fail, and the same 8 fail on main without this change.

Documentation

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[AriPerkkio]

Should JUnit reporter escape these? It seems there's no standarized answer for this.

🤖 says:

ANSI escape handling in JUnit reporters

Legend: ✅ the whole ANSI sequence is removed, ❌ it is not (something is left in the XML), — the reporter does not write that field.

Reporter	testcase name / classname	failure message	failure body	system-out / system-err	What ❌ fields contain
Vitest (main)	❌	❌	✅	❌	[31m
cargo-nextest	✅	✅	✅	✅
Mocha built-in xunit	✅	—	✅	—
Playwright (default)	❌	✅	✅	❌	[31m
Playwright (stripANSIControlSequences)	✅	✅	✅	✅
jest-junit	❌	—	✅	❌	see notes
mocha-junit-reporter	✅	❌	❌	✅	[31m
PHPUnit	❌	—	❌	❌	[31m
pytest	❌	❌	❌	❌	#x1B[31m
Maven Surefire	❌	❌	❌	❌	&amp#27;[31m
go-junit-report	❌	—	❌	❌	�[31m (U+FFFD)
rspec_junit_formatter	❌	❌	❌	❌	Ruby-style escape + [31m

We should probably add a reporters: [['junit', { stripAnsi: boolean }]] option for this. As we are already removing ANSI codes from body in writeErrorElement, it might be tricky to decide what the default value is. Maybe the type should be stripAnsi: true | false | 'error-bodies-only', and the default would be 'error-bodies-only'. 🤔

[meganemura]

@AriPerkkio Thanks. I read #4958 and #5007, where always stripping was declined. I think the reasons for stripping everything are different now, so I want to suggest it once more before I add an option.

1. Since fix(reporter): use default error formatter for JUnit #5629, the reporter strips ANSI from the <failure> / <error> body with stripVTControlCharacters. The message attribute comes from the same error, but there only ESC is removed, so text like [36m<body>[39m stays. The same happens in test names, system-out / system-err, and annotations.
2. XML 1.0 cannot hold the colors. ESC is not in the Char production, a character reference  breaks the "Legal Character" constraint, and CDATA also allows only Char. So removeInvalidXMLCharacters always removes ESC. This is not specific to Vitest: Playwright's JUnit reporter also removes ESC when it escapes XML. Without stripping, a user's console.log colors become [31m text, not colors. The concern in fix(vitest): strip ansi code from console output in junit reporter #5007 was about keeping colors, but no option value can keep them.

So I suggest keeping this PR as it is: strip ANSI everywhere. I will also update the description, because it lists only some of the places this change affects.

If you still want an option, how about using the Playwright default as our default? It strips only the parts built from the error: the message attribute, the body, and the stack trace. Then true strips ANSI everywhere.

[AriPerkkio]

So removeInvalidXMLCharacters always removes ESC.

Ohh I wasn't aware of that. In that case, it's not even possible to preserve colors in these reports (like it was thought in #5007 (comment)).

Removing all ANSI escapes in escapeXML sounds good to me. It's bug fix, not breaking change in my opinion. @hi-ogawa thoughts?

[hi-ogawa]

Makes sense 👍