Fix concatenation bug in "Report a docs issue" URLs (#3046)

* Fix bug that duplicates docs segment in URLs

* Add regression tests for report issue URL and breadcrumb URL path prefix duplication

Agent-Logs-Url: https://github.com/elastic/docs-builder/sessions/e2174a2c-285c-407b-984e-41a8e2d61217

Co-authored-by: Mpdreamz <245275+Mpdreamz@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Mpdreamz <245275+Mpdreamz@users.noreply.github.com>

Author: 3 people

src/Elastic.Markdown/HtmlWriter.cs

@@ -88,7 +88,7 @@ private async Task<RenderResult> RenderLayout(MarkdownFile markdown, MarkdownDoc
 		Uri? reportLinkParameter = null;
 		if (DocumentationSet.Context.CanonicalBaseUrl is not null)
 		{
-			reportLinkParameter = new Uri(DocumentationSet.Context.CanonicalBaseUrl, UrlPath.JoinUrl(DocumentationSet.Context.UrlPathPrefix ?? string.Empty, current.Url));
+			reportLinkParameter = new Uri(DocumentationSet.Context.CanonicalBaseUrl, current.Url);
 		}
 		var reportUrl = $"https://github.com/elastic/docs-content/issues/new?template=issue-report.yaml&link={reportLinkParameter}&labels=source:web";
 
@@ -195,7 +195,7 @@ private BreadcrumbsList CreateStructuredBreadcrumbsData(MarkdownFile markdown, I
 		{
 			Position = position++,
 			Name = parent.NavigationTitle,
-			Item = new Uri(DocumentationSet.Context.CanonicalBaseUrl ?? new Uri("http://localhost"), UrlPath.JoinUrl(DocumentationSet.Context.UrlPathPrefix ?? string.Empty, parent.Url)).ToString()
+			Item = new Uri(DocumentationSet.Context.CanonicalBaseUrl ?? new Uri("http://localhost"), parent.Url).ToString()
 		}));
 		// Add current page
 		breadcrumbItems.Add(new BreadcrumbListItem

tests/Elastic.Markdown.Tests/DocSet/ReportIssueUrlTests.cs

@@ -0,0 +1,106 @@
+// Licensed to Elasticsearch B.V under one or more agreements.
+// Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information
+
+using System.IO.Abstractions.TestingHelpers;
+using AwesomeAssertions;
+using Elastic.Documentation;
+using Elastic.Documentation.Configuration;
+using Elastic.Documentation.Configuration.Builder;
+using Elastic.Documentation.Navigation;
+using Elastic.Markdown.IO;
+using Nullean.ScopedFileSystem;
+
+namespace Elastic.Markdown.Tests.DocSet;
+
+/// <summary>
+/// Tests that the "Report a docs issue" URL and breadcrumb structured-data URLs
+/// are built correctly and never contain a duplicated path prefix (e.g. /docs/docs/).
+///
+/// Regression guard for: https://github.com/elastic/docs-content/issues/5788
+/// The bug was that HtmlWriter called UrlPath.JoinUrl(UrlPathPrefix, current.Url),
+/// but current.Url already contains the prefix because navigation sets PathPrefix = UrlPathPrefix.
+/// </summary>
+public class ReportIssueUrlTests : IAsyncLifetime
+{
+	private static readonly Uri CanonicalBaseUrl = new("https://www.elastic.co/");
+	private const string UrlPathPrefix = "docs";
+
+	private DocumentationSet Set { get; }
+	private DocumentationGenerator Generator { get; }
+
+	public ReportIssueUrlTests(ITestOutputHelper output)
+	{
+		var loggerFactory = new TestLoggerFactory(output);
+		var mockWriteFs = new MockFileSystem(new MockFileSystemOptions
+		{
+			CurrentDirectory = Paths.WorkingDirectoryRoot.FullName
+		});
+		var readFileSystem = FileSystemFactory.RealRead;
+		var writeFileSystem = FileSystemFactory.ScopeCurrentWorkingDirectory(mockWriteFs);
+		var collector = new TestDiagnosticsCollector(output);
+		var configurationContext = TestHelpers.CreateConfigurationContext(readFileSystem);
+
+		var context = new BuildContext(collector, readFileSystem, writeFileSystem, configurationContext, ExportOptions.Default)
+		{
+			Force = false,
+			UrlPathPrefix = UrlPathPrefix,
+			CanonicalBaseUrl = CanonicalBaseUrl
+		};
+
+		Set = new DocumentationSet(context, loggerFactory, new TestCrossLinkResolver());
+		Generator = new DocumentationGenerator(Set, loggerFactory);
+	}
+
+	public async ValueTask InitializeAsync() => await Generator.ResolveDirectoryTree(default);
+
+	public ValueTask DisposeAsync()
+	{
+		GC.SuppressFinalize(this);
+		return ValueTask.CompletedTask;
+	}
+
+	[Fact]
+	public void NavigationItemUrls_WithUrlPathPrefix_AlreadyIncludeThePrefix()
+	{
+		// When UrlPathPrefix = "docs", the navigation PathPrefix is "/docs",
+		// so every navigation item URL should already start with "/docs/".
+		var navUrl = Set.Navigation.Url;
+
+		navUrl.Should().StartWith($"/{UrlPathPrefix}");
+	}
+
+	[Fact]
+	public void ReportIssueUrl_WithUrlPathPrefix_DoesNotDuplicatePrefix()
+	{
+		// Simulate exactly what HtmlWriter does to build the report link parameter:
+		//   reportLinkParameter = new Uri(CanonicalBaseUrl, current.Url)
+		// current.Url already contains "/docs/..." because navigation incorporates PathPrefix.
+		// Prepending UrlPathPrefix a second time would produce "/docs/docs/…" (the old bug).
+		var currentUrl = Set.Navigation.Url;
+		var reportLinkParameter = new Uri(CanonicalBaseUrl, currentUrl);
+
+		reportLinkParameter.AbsoluteUri.Should().NotContain($"/{UrlPathPrefix}/{UrlPathPrefix}/");
+		reportLinkParameter.AbsoluteUri.Should().StartWith($"{CanonicalBaseUrl.AbsoluteUri.TrimEnd('/')}/{UrlPathPrefix}");
+	}
+
+	[Fact]
+	public void BreadcrumbUrl_WithUrlPathPrefix_DoesNotDuplicatePrefix()
+	{
+		// Simulate what HtmlWriter does for breadcrumb structured data:
+		//   Item = new Uri(CanonicalBaseUrl ?? localhost, parent.Url).ToString()
+		// Same bug would have applied here if the old JoinUrl call had been used.
+		INavigationTraversable traversable = Set;
+		var nestedFile = Set.MarkdownFiles
+			.First(f => traversable.GetParentsOfMarkdownFile(f).Length > 0);
+		var parents = traversable.GetParentsOfMarkdownFile(nestedFile);
+
+		parents.Should().NotBeEmpty();
+		foreach (var parent in parents)
+		{
+			var breadcrumbUrl = new Uri(CanonicalBaseUrl, parent.Url).ToString();
+
+			breadcrumbUrl.Should().NotContain($"/{UrlPathPrefix}/{UrlPathPrefix}/");
+		}
+	}
+}