Fix OpenAPI generator crash on routes starting with '~'

[Copilot]

Fix OpenAPI generator crash on routes starting with '~'

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Store RoutePattern on ApiDescription to avoid reparsing

Description

MapRelativePathToItemPath was reparsing RelativePath with RoutePatternFactory.Parse(), which fails for routes starting with ~ since the stored path lacks the leading / (e.g., ~health vs /~health).

Solution: Add RoutePattern property to ApiDescription and populate it in both providers:

• EndpointMetadataApiDescriptionProvider uses routeEndpoint.RoutePattern
• DefaultApiDescriptionProvider parses from AttributeRouteInfo.Template (simplified assignment based on code review)
• MapRelativePathToItemPath uses stored pattern, falls back to parsing for compatibility

Example:

builder.MapGet("/~health", () => Results.Ok("Healthy"));
builder.MapOpenApi(); // Previously crashed, now works

Changes:

• Added RoutePattern property to ApiDescription
• Updated both API description providers to set the property
• Modified MapRelativePathToItemPath to use pre-parsed pattern
• Added routing assembly reference to Mvc.Abstractions
• Updated PublicAPI files
• Simplified RoutePattern assignment logic in DefaultApiDescriptionProvider

Tests:

• Added 6 unit tests verifying routes starting with ~ (covering both /~health and ~/health patterns)
• Added integration tests for minimal API endpoints with both ~ route patterns
• Added integration tests for MVC controller actions with both ~ route patterns (2 tests)

All tests cover both the unusual /~ pattern (tilde after slash) that caused the crash and the normal ~/ pattern (tilde before slash) to ensure comprehensive coverage.

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[captainsafia]

@copilot Add a test that validates the behavior of these types of paths from a controller action.

[Copilot]

Added test GetOpenApiPaths_HandlesRoutesStartingWithTilde_MvcAction that validates routes starting with ~ from MVC controller actions. The test uses a controller action with [Route("/~health")] attribute and verifies the OpenAPI document is generated correctly. Commit: e48e103

[Copilot]

Pull request overview

This PR fixes a crash in the OpenAPI generator when handling routes that start with the '~' character by storing the parsed RoutePattern on ApiDescription instead of reparsing the RelativePath string.

Changes:

• Added RoutePattern property to ApiDescription class to cache the parsed route pattern
• Updated both API description providers (EndpointMetadataApiDescriptionProvider and DefaultApiDescriptionProvider) to populate the new property
• Modified MapRelativePathToItemPath to use the cached pattern with fallback to parsing for backward compatibility

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/Mvc/Mvc.Abstractions/src/ApiExplorer/ApiDescription.cs	Added RoutePattern property with XML documentation
src/Mvc/Mvc.Abstractions/src/Microsoft.AspNetCore.Mvc.Abstractions.csproj	Added reference to Microsoft.AspNetCore.Routing assembly
src/Mvc/Mvc.Abstractions/src/PublicAPI.Unshipped.txt	Documented public API additions for RoutePattern getter/setter
src/Mvc/Mvc.ApiExplorer/src/PublicAPI.Unshipped.txt	Documented forwarded API from Mvc.Abstractions
src/Mvc/Mvc.ApiExplorer/src/EndpointMetadataApiDescriptionProvider.cs	Set RoutePattern from routeEndpoint.RoutePattern
src/Mvc/Mvc.ApiExplorer/src/DefaultApiDescriptionProvider.cs	Parse and set RoutePattern from AttributeRouteInfo.Template
src/OpenApi/src/Extensions/ApiDescriptionExtensions.cs	Use cached RoutePattern or fallback to parsing RelativePath
src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Extensions/ApiDescriptionExtensionsTests.cs	Added unit tests for routes starting with '~'
src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Services/OpenApiDocumentService/OpenApiDocumentServiceTests.Paths.cs	Added integration tests for minimal API and MVC routes with '~'

[captainsafia]

/azp run

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