Fix string handling edge cases and case-insensitive URL/file detection

[Copilot]

Description:

Fixes several bugs discovered during codebase analysis:

String handling edge cases (StringExtensions.cs)

• CapitalizeFirstCharacter() threw ArgumentOutOfRangeException on empty strings
• Added null/empty guard and single-character handling

Case-insensitive URL/file detection (OpenApiDocumentFactory.cs, OpenApiValidator.cs)

• IsHttp() failed for uppercase URLs like HTTP:// or HTTPS://
• IsYaml() matched filenames like notayaml instead of only .yaml/.yml extensions
• GetStream() used case-sensitive HTTP check

Unnecessary FileInfo allocation (OpenApiValidator.cs)

• ParseOpenApi() created FileInfo for HTTP URLs; refactored to only allocate when processing file paths

Example fix for CapitalizeFirstCharacter:

// Before: throws on empty string
return str.Substring(0, 1).ToUpperInvariant() + str.Substring(1, str.Length - 1);

// After: handles edge cases
if (string.IsNullOrEmpty(str))
    return str;
if (str.Length == 1)
    return str.ToUpperInvariant();
return str.Substring(0, 1).ToUpperInvariant() + str.Substring(1, str.Length - 1);

Example fix for IsYaml:

// Before: matches "notayaml"
return path.EndsWith("yaml") || path.EndsWith("yml");

// After: requires dot prefix, case-insensitive
return path.EndsWith(".yaml", StringComparison.OrdinalIgnoreCase) || 
       path.EndsWith(".yml", StringComparison.OrdinalIgnoreCase);

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• demo.netbox.dev
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/HttpGenerator.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/HttpGenerator.Tests.deps.json /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/testhost.dll --port 44509 --endpoint 127.0.0.1:044509 --role client --parentprocessid 3654 --telemetryoptedin false (dns block)
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/HttpGenerator.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/HttpGenerator.Tests.deps.json /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/testhost.dll --port 36815 --endpoint 127.0.0.1:036815 --role client --parentprocessid 4630 --telemetryoptedin false (dns block)
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/HttpGenerator.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/HttpGenerator.Tests.deps.json /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/testhost.dll --port 39719 --endpoint 127.0.0.1:039719 --role client --parentprocessid 5588 --telemetryoptedin false (dns block)
• developers.intellihr.io
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/HttpGenerator.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/HttpGenerator.Tests.deps.json /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/testhost.dll --port 44509 --endpoint 127.0.0.1:044509 --role client --parentprocessid 3654 --telemetryoptedin false (dns block)
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/HttpGenerator.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/HttpGenerator.Tests.deps.json /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/testhost.dll --port 36815 --endpoint 127.0.0.1:036815 --role client --parentprocessid 4630 --telemetryoptedin false (dns block)
  • Triggering command: /usr/share/dotnet/dotnet /usr/share/dotnet/dotnet exec --runtimeconfig /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/HttpGenerator.Tests.runtimeconfig.json --depsfile /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/HttpGenerator.Tests.deps.json /home/REDACTED/work/httpgenerator/httpgenerator/src/HttpGenerator.Tests/bin/Release/net8.0/testhost.dll --port 39719 --endpoint 127.0.0.1:039719 --role client --parentprocessid 5588 --telemetryoptedin false (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

Find and resolve bugs and issue in the current code base. Be as thorough as possible

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

❌ Patch coverage is 85.71429% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.12%. Comparing base (3d6a413) to head (4d55b0a).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/HttpGenerator.Core/OpenApiDocumentFactory.cs	50.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #290      +/-   ##
==========================================
+ Coverage   84.93%   85.12%   +0.18%     
==========================================
  Files          12       12              
  Lines         551      558       +7     
  Branches       76       78       +2     
==========================================
+ Hits          468      475       +7     
  Misses         70       70              
  Partials       13       13              

Flag	Coverage Δ
unittests	85.12% <85.71%> (+0.18%)	⬆️

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[Copilot]

Pull request overview

This PR fixes critical string handling bugs and improves robustness of URL/file detection logic across the codebase.

Key changes:

• Added null/empty guards to CapitalizeFirstCharacter() to prevent ArgumentOutOfRangeException
• Implemented case-insensitive protocol detection for HTTP/HTTPS URLs in IsHttp() and IsYaml()
• Refactored ParseOpenApi() to avoid unnecessary FileInfo allocation for HTTP URLs

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
src/HttpGenerator.Core/StringExtensions.cs	Adds null/empty/single-character guards to prevent crashes in CapitalizeFirstCharacter()
src/HttpGenerator.Tests/StringExtensionsTests.cs	Adds test coverage for edge cases (empty string and single character)
src/HttpGenerator.Core/OpenApiDocumentFactory.cs	Makes IsHttp() and IsYaml() case-insensitive with proper protocol/extension matching
src/HttpGenerator/Validation/OpenApiValidator.cs	Updates GetStream() and ParseOpenApi() to use case-insensitive HTTP detection and avoid unnecessary FileInfo allocation

[Copilot]

The condition input.StartsWith("http", StringComparison.OrdinalIgnoreCase) is too broad and will match invalid strings like "httpxyz", "httpasdf://example.com", or even "HTTP" without the protocol separator. This inconsistency with IsHttp() in OpenApiDocumentFactory.cs (which correctly checks for "http://" and "https://") can lead to incorrect classification.

Consider changing this to match the pattern used in OpenApiDocumentFactory.cs:

if (input.StartsWith("http://", StringComparison.OrdinalIgnoreCase) || 
    input.StartsWith("https://", StringComparison.OrdinalIgnoreCase))

[Copilot]

The condition openApiFile.StartsWith("http", StringComparison.OrdinalIgnoreCase) is too broad and will match invalid strings like "httpxyz", "httpasdf://example.com", or even "HTTP" without the protocol separator. This inconsistency with IsHttp() in OpenApiDocumentFactory.cs (which correctly checks for "http://" and "https://") can lead to incorrect classification and unnecessary new Uri(openApiFile) calls that may throw UriFormatException.

Consider changing this to match the pattern used in OpenApiDocumentFactory.cs:

if (openApiFile.StartsWith("http://", StringComparison.OrdinalIgnoreCase) || 
    openApiFile.StartsWith("https://", StringComparison.OrdinalIgnoreCase))

[Copilot]

The case-insensitive URL detection fix lacks test coverage for edge cases like uppercase URLs (e.g., "HTTP://example.com", "HTTPS://example.com"). Consider adding test cases in OpenApiDocumentFactoryTests.cs to verify that CreateAsync correctly handles uppercase URL protocols:

[Theory]
[InlineData("HTTP://raw.githubusercontent.com/christianhelle/httpgenerator/main/test/OpenAPI/v3.0/petstore.json")]
[InlineData("HTTPS://raw.githubusercontent.com/christianhelle/httpgenerator/main/test/OpenAPI/v3.0/petstore.json")]
public async Task Create_From_Uri_With_Uppercase_Protocol_Returns_NotNull(string url)
{
    (await OpenApiDocumentFactory.CreateAsync(url))
        .Should()
        .NotBeNull();
}

[Copilot]

The improved IsYaml() method that now correctly requires a dot prefix and is case-insensitive lacks test coverage. Consider adding test cases in OpenApiDocumentFactoryTests.cs to verify that files with uppercase extensions are handled correctly:

[Theory]
[InlineData(Samples.PetstoreYamlV3, "SwaggerPetstore.YAML")]
[InlineData(Samples.PetstoreYamlV3, "SwaggerPetstore.YML")]
public async Task Create_From_Yaml_File_With_Uppercase_Extension_Returns_NotNull(Samples version, string filename)
{
    var swaggerFile = await TestFile.CreateSwaggerFile(EmbeddedResources.GetSwaggerPetstore(version), filename);
    (await OpenApiDocumentFactory.CreateAsync(swaggerFile))
        .Should()
        .NotBeNull();
}