Ignore formatting changes from Html that change non-whitespace characters

[davidwengier]

Fixes https://devdiv.visualstudio.com/DevDiv/_workitems/edit/3042344 / https://devdiv.visualstudio.com/DevDiv/_workitems/edit/3040290

This is an odd one, where the JavaScript formatter is removing legitimate code because its confused by Razor concepts. Not a lot we can do about it in terms of nice formatting, but we can not error out and crash at least. So this does that.

Microsoft Reviewers: Open in CodeFlow

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[Copilot]

Pull request overview

This PR hardens Razor HTML formatting by filtering out HTML-formatter edits that change non-whitespace characters (to avoid destructive “formatting” in Razor/script scenarios), and adds regression coverage via both targeted unit tests and captured formatting logs.

Changes:

• Filter out HTML-formatter TextChanges whose replacement would alter non-whitespace content in HtmlFormattingPass.
• Add focused unit tests covering “equivalent non-whitespace” edits and mixed safe/unsafe edits around length changes.
• Add two real-world formatting-log regressions (PageForGrid / PageForMultiGrid) and corresponding test entries.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Formatting/Passes/HtmlFormattingPass.cs	Adds filtering to drop HTML-formatter edits that change non-whitespace content.
src/Razor/src/Razor/test/Microsoft.CodeAnalysis.Razor.CohostingShared.UnitTests/Formatting/HtmlFormattingPassTest.cs	Adds unit tests validating non-whitespace-preserving edits are kept and unsafe edits don’t disrupt surrounding whitespace edits.
src/Razor/src/Razor/test/Microsoft.CodeAnalysis.Razor.CohostingShared.UnitTests/Formatting/DocumentFormattingTest.cs	Adds an end-to-end regression ensuring non-whitespace corruption in <script> is ignored.
src/Razor/src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.UnitTests/Cohost/Formatting/FormattingLogTest.cs	Registers new formatting-log-based regressions as tests.
src/Razor/src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.UnitTests/TestFiles/FormattingLog/PageForMultiGrid/InitialDocument.txt	Adds captured initial document for the MultiGrid formatting regression.
src/Razor/src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.UnitTests/TestFiles/FormattingLog/PageForMultiGrid/HtmlChanges.json	Adds captured HTML formatter changes for the MultiGrid regression.
src/Razor/src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.UnitTests/TestFiles/FormattingLog/PageForMultiGrid/Options.json	Adds captured formatting options for the MultiGrid regression.
src/Razor/src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.UnitTests/TestFiles/FormattingLog/PageForMultiGrid/Range.json	Adds captured range info for the MultiGrid regression.
src/Razor/src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.UnitTests/TestFiles/FormattingLog/PageForMultiGrid/FileKind.json	Adds captured file kind for the MultiGrid regression.
src/Razor/src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.UnitTests/TestFiles/FormattingLog/PageForGrid/InitialDocument.txt	Adds captured initial document for the Grid formatting regression.
src/Razor/src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.UnitTests/TestFiles/FormattingLog/PageForGrid/HtmlChanges.json	Adds captured HTML formatter changes for the Grid regression.
src/Razor/src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.UnitTests/TestFiles/FormattingLog/PageForGrid/Options.json	Adds captured formatting options for the Grid regression.
src/Razor/src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.UnitTests/TestFiles/FormattingLog/PageForGrid/Range.json	Adds captured range info for the Grid regression.
src/Razor/src/Razor/test/Microsoft.VisualStudio.LanguageServices.Razor.UnitTests/TestFiles/FormattingLog/PageForGrid/FileKind.json	Adds captured file kind for the Grid regression.

[Copilot]

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated 1 comment.

Suppressed comments (1)

src/Razor/src/Razor/test/Microsoft.CodeAnalysis.Razor.CohostingShared.UnitTests/Formatting/DocumentFormattingTest.cs:1334

• The expected formatted output has inconsistent indentation on the const ids = ... line (it appears to have extra leading spaces compared to the surrounding <text> block and the input/htmlFormatted strings). This is likely to make the regression test fail for the wrong reason.

                              const ids = grid.getIds();

[Copilot]

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated no new comments.

Suppressed comments (2)

src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Formatting/Passes/HtmlFormattingPass.cs:214

• FilterOutNonWhitespaceChanges allocates changedText via originalText.WithChanges(candidateChanges) even though formattedText (computed earlier in this method) should already represent the result of applying candidateChanges. Reusing formattedText avoids an extra full-text rewrite/allocation in this warning-path.

            var changedText = originalText.WithChanges(candidateChanges);

src/Razor/src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Formatting/Passes/HtmlFormattingPass.cs:245

• The warning message is very generic and can be noisy in logs without giving enough diagnostic value. Including how many changes were dropped (and total) would make the warning actionable when this happens in the wild.

            _logger.LogWarning("Ignoring non-whitespace changes returned by the HTML formatter.");