[dotnet] Convert resource utility build step to C# source generator

[RenderMichael]

User description

Follow-up on https://github.com/SeleniumHQ/selenium/commit/4c0eb7f2e5bc5161b67c724feb7cab6fe33624c2#r171146028

🔗 Related Issues

💥 What does this PR do?

🔧 Implementation Notes

💡 Additional Considerations

🔄 Types of changes

• Cleanup (formatting, renaming)

---

PR Type

Enhancement

---

Description

• Replaces build-time resource generation with C# source generator

• Adds Microsoft.CodeAnalysis NuGet dependencies for code generation

• Removes legacy generated_resource_utilities Bazel rule

• Integrates source generator into WebDriver compilation pipeline

---

Diagram Walkthrough

flowchart LR
  A["Build-time Resource Generation"] -->|replaced by| B["C# Source Generator"]
  C["JavaScript/JSON Files"] -->|processed by| B
  B -->|generates| D["ResourceUtilities.g.cs"]
  D -->|compiled into| E["WebDriver Assembly"]

File Walkthrough

	Relevant files
Enhancement	1 files ResourceUtilitiesAtomGenerator.cs New incremental source generator for resource utilities    +142/-0
Configuration changes	7 files Selenium.WebDriver.SourceGenerator.csproj Project file for source generator NuGet package                    +24/-0    BUILD.bazel Bazel build configuration for source generator library      +25/-0    .analyzerconfig Analyzer configuration for extended rules enforcement        +1/-0      defs.bzl Remove generated_resource_utilities Bazel rule export        +0/-2      Selenium.sln Add source generator project to Visual Studio solution      +6/-0      BUILD.bazel Replace resource generation with source generator dependency +33/-21  Selenium.WebDriver.csproj Add source generator analyzer and AdditionalFiles references +13/-6
Dependencies	2 files paket.dependencies Add Microsoft.CodeAnalysis NuGet package dependencies        +3/-0      paket.nuget.bzl Update NuGet package definitions with CodeAnalysis packages +8/-1

---

[qodo-code-review[bot]]

PR Compliance Guide 🔍

Below is a summary of compliance checks for this PR:

Security Compliance
⚪	Out-of-bounds read Description: The kebab-to-Pascal case conversion reads the next character after a non-letter without bounds checking, which can read past the end of the string when the input ends with a non-letter (e.g., trailing dash), risking an IndexOutOfRangeException during generation. ResourceUtilitiesAtomGenerator.cs [118-141] Referred Code private static string KebabCaseToPascalCase(string v) { Span<char> newValues = new char[v.Length]; int newValuesOffset = 0; for (int i = 0; i < v.Length; i++) { if (i == 0) { newValues[i - newValuesOffset] = char.ToUpperInvariant(v[i]); } else if (char.IsLetter(v[i])) { newValues[i - newValuesOffset] = v[i]; } else { i++; newValuesOffset++; newValues[i - newValuesOffset] = char.ToUpperInvariant(v[i]); } } ... (clipped 3 lines)
Ticket Compliance
🟡	🎫 #5678 🔴 Investigate and resolve ChromeDriver connection failures showing "Error: ConnectFailure (Connection refused)" when instantiating multiple ChromeDriver instances on Ubuntu 16.04 with Chrome 65/ChromeDriver 2.35 using Selenium 3.9.0. Provide a fix or guidance so subsequent ChromeDriver instantiations do not log the ConnectFailure error. Validate behavior across multiple instantiations and ensure console remains free of the reported error after the first instance.
🟡	🎫 #1234 🔴 Ensure WebDriver click() triggers JavaScript in link href as it did in 2.47.1, fixing regressions observed in 2.48.x on Firefox 42. Provide tests validating that clicking executes the JS handler in Firefox.
Codebase Duplication Compliance
⚪	Codebase context is not defined Follow the guide to enable codebase context checks.
Custom Compliance
🟢	Generic: Meaningful Naming and Self-Documenting Code Objective: Ensure all identifiers clearly express their purpose and intent, making code self-documenting Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Secure Error Handling Objective: To prevent the leakage of sensitive system information through error messages while providing sufficient detail for internal debugging. Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Secure Logging Practices Objective: To ensure logs are useful for debugging and auditing without exposing sensitive information like PII, PHI, or cardholder data. Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
⚪	Generic: Comprehensive Audit Trails Objective: To create a detailed and reliable record of critical system actions for security analysis and compliance. Status: No audit logs: The new source generator processes files and emits diagnostics but does not log any critical security-relevant actions, which may be acceptable for build-time tooling but cannot be verified from the diff. Referred Code public void Initialize(IncrementalGeneratorInitializationContext context) { var jsFiles = context.AdditionalTextsProvider .Where(static (text) => text.Path.EndsWith(".js") || text.Path.EndsWith(".json")) .WithTrackingName("AtomFiles") .Select(static (data, token) => { var name = Path.GetFileName(data.Path); var code = GenerateAtom(data, token, out var diagnostics); return (name, code, diagnostics); }); context.RegisterSourceOutput(jsFiles, static (context, pair) => { foreach (var diagnostic in pair.diagnostics) { context.ReportDiagnostic(diagnostic); } if (pair.code is not null) { ... (clipped 10 lines) Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Robust Error Handling and Edge Case Management Objective: Ensure comprehensive error handling that provides meaningful context and graceful degradation Status: Limited errors: The generator reports diagnostics for unreadable sources and unknown files but lacks handling for null/empty AdditionalFiles inputs and potential index bounds in KebabCaseToPascalCase, which might cause build-time failures without clear context. Referred Code private static string KebabCaseToPascalCase(string v) { Span<char> newValues = new char[v.Length]; int newValuesOffset = 0; for (int i = 0; i < v.Length; i++) { if (i == 0) { newValues[i - newValuesOffset] = char.ToUpperInvariant(v[i]); } else if (char.IsLetter(v[i])) { newValues[i - newValuesOffset] = v[i]; } else { i++; newValuesOffset++; newValues[i - newValuesOffset] = char.ToUpperInvariant(v[i]); } } ... (clipped 3 lines) Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Security-First Input Validation and Data Handling Objective: Ensure all data inputs are validated, sanitized, and handled securely to prevent vulnerabilities Status: Input validation: The generator accepts arbitrary .js/.json AdditionalFiles and embeds their contents into constants without explicit size or content validation, which is likely fine for build-time controlled inputs but cannot be fully assessed from the diff. Referred Code var jsFiles = context.AdditionalTextsProvider .Where(static (text) => text.Path.EndsWith(".js") || text.Path.EndsWith(".json")) .WithTrackingName("AtomFiles") .Select(static (data, token) => { var name = Path.GetFileName(data.Path); var code = GenerateAtom(data, token, out var diagnostics); return (name, code, diagnostics); }); context.RegisterSourceOutput(jsFiles, static (context, pair) => { foreach (var diagnostic in pair.diagnostics) { context.ReportDiagnostic(diagnostic); } if (pair.code is not null) { var propertyName = GetPropertyNameFromFilePath(pair.name, out _, out var diag); if (diag is not null) ... (clipped 6 lines) Learn more about managing compliance generic rules or creating your own custom rules
[ ] Update <!-- /compliance --update_compliance=true -->

Compliance status legend

🟢 - Fully Compliant
🟡 - Partial Compliant
🔴 - Not Compliant
⚪ - Requires Further Human Verification
🏷️ - Compliance label

[qodo-code-review[bot]]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
High-level	The Bazel build configuration is incorrect The Bazel build configuration in dotnet/src/webdriver/BUILD.bazel is incorrect. It uses the resources attribute to provide files to the new source generator, but it should use additional_files to ensure the generator receives them correctly during a Bazel build. Examples: dotnet/src/webdriver/BUILD.bazel [43-49] resources = [ "//javascript/atoms/fragments:find-elements.js", "//javascript/atoms/fragments:is-displayed.js", "//javascript/cdp-support:mutation-listener.js", "//javascript/webdriver/atoms:get-attribute.js", "//third_party/js/selenium:webdriver_json", ], Solution Walkthrough: Before: # In dotnet/src/webdriver/BUILD.bazel csharp_library( name = "webdriver-netstandard2.0", srcs = [ ... ], # ... resources = [ "//javascript/atoms/fragments:find-elements.js", "//javascript/atoms/fragments:is-displayed.js", "//javascript/cdp-support:mutation-listener.js", "//javascript/webdriver/atoms:get-attribute.js", "//third_party/js/selenium:webdriver_json", ], # ... deps = [ # ... "//dotnet/private/Selenium.WebDriver.SourceGenerator:resource-utilities-generator", ], ) After: # In dotnet/src/webdriver/BUILD.bazel csharp_library( name = "webdriver-netstandard2.0", srcs = [ ... ], # ... additional_files = [ "//javascript/atoms/fragments:find-elements.js", "//javascript/atoms/fragments:is-displayed.js", "//javascript/cdp-support:mutation-listener.js", "//javascript/webdriver/atoms:get-attribute.js", "//third_party/js/selenium:webdriver_json", ], # ... deps = [ # ... "//dotnet/private/Selenium.WebDriver.SourceGenerator:resource-utilities-generator", ], ) Suggestion importance[1-10]: 9 __ Why: The suggestion correctly identifies a critical flaw in the Bazel build configuration where resources are used instead of the required additional_files attribute, which will cause the source generator to fail and break the build.	High
Possible issue	Remove duplicate additional file entry Remove the duplicate <AdditionalFiles> entry for get-attribute.js in Selenium.WebDriver.csproj. This duplication would cause the source generator to fail and break the build. dotnet/src/webdriver/Selenium.WebDriver.csproj [90-94] -<AdditionalFiles Include="$(ProjectDir)..\..\..\bazel-bin\javascript\webdriver\atoms\get-attribute.js" /> <AdditionalFiles Include="$(ProjectDir)..\..\..\bazel-bin\javascript\webdriver\atoms\get-attribute.js" /> <AdditionalFiles Include="$(ProjectDir)..\..\..\bazel-bin\javascript\atoms\fragments\is-displayed.js" /> <AdditionalFiles Include="$(ProjectDir)..\..\..\bazel-bin\javascript\atoms\fragments\find-elements.js" /> <AdditionalFiles Include="$(ProjectDir)..\..\..\javascript\cdp-support\mutation-listener.js" /> [ ] Apply / Chat <!-- /improve --apply_suggestion=1 --> Suggestion importance[1-10]: 9 __ Why: The suggestion correctly identifies a duplicate AdditionalFiles entry for get-attribute.js which would cause a build failure due to the source generator creating duplicate code. This is a critical fix to make the build succeed.	High
	Prevent out-of-bounds array access Refactor the KebabCaseToPascalCase method to prevent a potential IndexOutOfRangeException when the input string ends with a non-letter character. The suggested implementation using string.Split is safer and more robust. dotnet/private/Selenium.WebDriver.SourceGenerator/ResourceUtilitiesAtomGenerator.cs [118-141] private static string KebabCaseToPascalCase(string v) { - Span<char> newValues = new char[v.Length]; - int newValuesOffset = 0; - for (int i = 0; i < v.Length; i++) + if (string.IsNullOrEmpty(v)) { - if (i == 0) + return string.Empty; + } + + var parts = v.Split(new[] { '-' }, StringSplitOptions.RemoveEmptyEntries); + var builder = new StringBuilder(); + foreach (var part in parts) + { + if (part.Length > 0) { - newValues[i - newValuesOffset] = char.ToUpperInvariant(v[i]); - } - else if (char.IsLetter(v[i])) - { - newValues[i - newValuesOffset] = v[i]; - } - else - { - i++; - newValuesOffset++; - newValues[i - newValuesOffset] = char.ToUpperInvariant(v[i]); + builder.Append(char.ToUpperInvariant(part[0])); + if (part.Length > 1) + { + builder.Append(part.AsSpan(1)); + } } } - - return newValues.Slice(0, v.Length - newValuesOffset).ToString(); + return builder.ToString(); } [ ] Apply / Chat <!-- /improve --apply_suggestion=2 --> Suggestion importance[1-10]: 8 __ Why: The suggestion correctly identifies an IndexOutOfRangeException bug in the KebabCaseToPascalCase method for certain inputs, and the proposed fix is more robust, readable, and idiomatic.	Medium
Learned best practice	Validate inputs and cancellation Check for token cancellation explicitly and return early with a diagnostic, and validate file content isn't empty to avoid generating invalid sources. dotnet/private/Selenium.WebDriver.SourceGenerator/ResourceUtilitiesAtomGenerator.cs [50-56] var sourceText = additionalText.GetText(token); -if (sourceText is null) +if (token.IsCancellationRequested) { - var d = Diagnostic.Create(new DiagnosticDescriptor("WRG1001", "Failed to read atom", "Atom '{0}' could not be read", "WebDriverResourceGenerator", DiagnosticSeverity.Error, true), Location.None, additionalText.Path); - diagnostics = [d]; + diagnostics = [Diagnostic.Create(new DiagnosticDescriptor("WRG1003", "Generation canceled", "Generation canceled while reading '{0}'", "WebDriverResourceGenerator", DiagnosticSeverity.Info, true), Location.None, additionalText.Path)]; + return null; +} +if (sourceText is null || sourceText.Length == 0) +{ + diagnostics = [Diagnostic.Create(new DiagnosticDescriptor("WRG1001", "Failed to read atom", "Atom '{0}' could not be read or was empty", "WebDriverResourceGenerator", DiagnosticSeverity.Error, true), Location.None, additionalText.Path)]; return null; } [ ] Apply / Chat <!-- /improve --apply_suggestion=3 --> Suggestion importance[1-10]: 6 __ Why: Relevant best practice - Guard external I/O operations with validation and clear error handling.	Low
[ ] Update <!-- /improve_multi --more_suggestions=true -->

[RenderMichael]

@nvborisenko Currently enabled for dotnet build only, for simplicity with local development.

I tried it for bazel but I got some strange exception, not from our layer. Looks like a dotnet_rules bug or something. https://github.com/SeleniumHQ/selenium/actions/runs/19604652783/job/56141409548#step:19:1425

If we can fix it for bazel, that would be great. Otherwise, I still see value with this PR as is.

[nvborisenko]

In general I will be happy to use native .NET SDK to develop Selenium without bazel. But sometimes we need external tool to generate source files. I see only one important reason: generated source files by generators cannot be as input files for other generators. Like we do CDP, we want to use JsonSerializerContext, which is treated by System.Text.Json.

In this particular case let's see the diff when CI is green.

[RenderMichael]

That’s a good point about the generator output being invisible to other generators. I will keep that in mind for something like CDP.

In this case, it seems harmless to use it for the resource utility files.

I am still investigating why it doesn’t work with Bazel. My suspicion is that bazel might not support the IIncrementalGenerator version of the source generator. Not sure yet.

[nvborisenko]

Internally bazel delegates everything to csc/msbuild. Might be useful: https://github.com/bazel-contrib/rules_dotnet/blob/master/examples/source_generators/generator_usage/BUILD.bazel

[RenderMichael]

I modelled my attempt on that example, you can see what I had a few commits ago. It failed with the stack trace in the build I linked, for some reason.

[RenderMichael]

As it is, I have the C# source generator enabled only for local dev and disabled for bazel; the CI is green. Maybe this PR is useful as is?

[nvborisenko]

We don't want to support 2 branches.

If it doesn't work in bazel, then it doesn't work at all. It has to work. csproj file is additionally supported.