[pedrorossato]

Fixes #1034

The built-in number format 17 (mmm-yy) was declared with typeof(TimeSpan). ConvertValueByStyleFormat only handles DateTime? and TimeSpan?, so cells using it were returned as the raw OADate serial. This declares it as typeof(DateTime?), like the other built-in date formats (14, 15, 16 and 22).

• ExcelOpenXmlStyles: format 17 type TimeSpan → DateTime?.
• MiniExcelIssueTests.QueryReadsBuiltInDateFormatsAsDateTime: reads the same serial with the built-in date formats 14, 15, 16, 17 and 22 and expects a DateTime; only the 17 case fails without the fix.
• Helpers.ReplaceStylesXml: test helper mirroring ReplaceFirstSheetXml.

MiniExcelTests passes locally (380/380, net10.0, Windows).

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on base/target branches other than the default branch.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

Run configuration

• Source mode: Auto
• Repository: Unavailable
• Branch: Unavailable
• File: No configuration file from this repository applied
• Commit: Unavailable
• Layers: defaults
• Review profile: CHILL
• Plan: Advanced
• Run ID: c2753b77-ec05-49f7-9d17-df3dc06803e2

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

• Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

_{Comment @coderabbitai help to get the list of available commands.}

[michelebastione]

Thank you for the contribution @pedrorossato! Could you please open a PR for fixing this on the master branch as well?