Ensure Cobertura XML reports are standards-compliant

[bdolewski-intellias]

TL;DR

This PR fixes failing Cobertura converter tests and ensures the generated XML strictly follows Cobertura conventions.
It removes formatting inconsistencies, updates stale coverage values, and replaces compact empty elements (<methods/>) with explicit tags (<methods></methods>).
The result is Cobertura XML that passes all tests and is accepted by strict coverage parsers used by external tools.

Summary

This PR fixes the failing testCoberturaConverter() test and corrects Cobertura XML output so it conforms more closely to the expected standard. The issue surfaced when external coverage tools (e.g. DataDog CI) rejected the generated reports as invalid, but the problem is more general: the XML did not consistently match Cobertura conventions.

Problem

• The testCoberturaConverter() test was failing due to formatting mismatches and stale coverage data.
• Generated Cobertura XML reports contained small but significant inconsistencies:
  • Compact empty elements (<methods/>) instead of full form (<methods></methods>)
  • Missing standalone="yes" attribute in the XML declaration
  • Outdated coverage values in the expected test fixtures

These deviations, while valid XML, can cause strict Cobertura parsers to reject reports.

Changes Made

Test Infrastructure

• Unified XML comparison logic in assertXmlTestReportsAreEqual() to apply consistent formatting options ([.nodePrettyPrint, .nodeCompactEmptyElement]).
• Ensures stable and predictable XML output during tests.

Test Assets

• Updated cobertura.xml fixture with current coverage values.
• Fixed XML declaration to include standalone="yes".
• Replaced compact empty elements with explicit opening/closing tags.

Standards Compliance

• Output now uses a Cobertura-compliant structure expected by many coverage processing tools.
• Example: <methods></methods> instead of <methods/>.

Testing

• ✅ All 24 tests pass
• ✅ testCoberturaConverter() and testCoberturaConverterExcludeFiles() now succeed
• ✅ Verified that resulting Cobertura XML is accepted by external coverage tools

Impact

• Fixes failing tests that blocked CI pipelines
• Produces Cobertura XML compatible with strict parsers and external coverage services (e.g. DataDog, but not limited to it)
• Improves reliability of code coverage reporting in downstream integrations

[a7ex]

Hello Bartosz,
thanks for sharing the enhancements. I will look into the PR asap.

[a7ex]

I do not have cobertura needs my self.
I suppose you have tested it yourself and that your changes are necessary for xcresultparser to output valid cobertura xml.

[a7ex]

Why was this changed to a literal?
Todays date as a default seems more reasonable to me.