[dotnet] Add reflection-based JSON serialization fallback to Commands

[RenderMichael]

User description

Fixes #14731

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Description

Adds a reflection-based JSON serialization fallback, preventing unchecked exceptions from breaking scenarios.

Motivation and Context

Exceptions are being thrown for unknown types, including anonymous types.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the contributing document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

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PR Type

Bug fix, Tests

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Description

• Introduced a reflection-based JSON serialization fallback in the Command class to handle unknown types, including anonymous types, preventing unchecked exceptions.
• Enhanced JSON serialization by combining CommandJsonSerializerContext.Default with DefaultJsonTypeInfoResolver.
• Added unit tests to verify the serialization of anonymous types within the Command class, ensuring robustness and correctness.

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Changes walkthrough 📝

	Relevant files
Enhancement	Command.cs Add reflection-based JSON serialization fallback in Command class dotnet/src/webdriver/Command.cs Added JsonTypeInfoResolver.Combine to JSON serializer options. Included DefaultJsonTypeInfoResolver for enhanced serialization. +2/-1
Tests	CommandTests.cs Add tests for JSON serialization of Command class                dotnet/test/common/CommandTests.cs Added new test class CommandTests. Implemented test for serializing anonymous types in commands. +22/-0

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[qodo-merge-pro]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 PR contains tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Performance Impact The reflection-based JSON serialization fallback could impact performance compared to the previous source-generated serialization. Consider measuring and documenting any performance differences. Test Coverage The test only covers a simple anonymous type case. Consider adding more test cases with nested anonymous types, null values, and complex object structures.

[qodo-merge-pro]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Score
Enhancement	Enhance test coverage by including edge cases in serialization tests Add test cases for edge cases like null values and empty dictionaries to ensure robust serialization handling. dotnet/test/common/CommandTests.cs [10-16] -[Test] -public void CommandSerializesAnonymousType() +[TestCase(null)] +[TestCase(new object())] +public void CommandSerializesAnonymousType(object value) { var parameters = new Dictionary<string, object> { - ["arg"] = new { param1 = true, param2 = false }, + ["arg"] = value, }; Apply this suggestion Suggestion importance[1-10]: 8 Why: Adding test cases for null and edge cases is crucial for ensuring robust serialization behavior, significantly improving the test coverage and helping prevent potential runtime issues.	8
Best practice	Improve thread safety and immutability by correctly ordering readonly and static modifiers Consider making the JsonSerializerOptions immutable by marking it as readonly to prevent accidental modifications at runtime. dotnet/src/webdriver/Command.cs [37] -private readonly static JsonSerializerOptions s_jsonSerializerOptions = new() +private static readonly JsonSerializerOptions s_jsonSerializerOptions = new() Apply this suggestion Suggestion importance[1-10]: 3 Why: While the suggestion to reorder modifiers follows C# best practices, it's a minor stylistic change that doesn't affect functionality as both forms are semantically equivalent.	3
	Improve code style by removing unnecessary trailing comma in collection initializer Remove trailing comma in dictionary initialization as it's not needed and may affect readability. dotnet/test/common/CommandTests.cs [12-15] var parameters = new Dictionary<string, object> { - ["arg"] = new { param1 = true, param2 = false }, + ["arg"] = new { param1 = true, param2 = false } }; Apply this suggestion Suggestion importance[1-10]: 2 Why: The suggestion addresses a minor style preference. Trailing commas are actually beneficial in C# as they make future additions easier and produce cleaner diffs, so removing them might not be an improvement.	2

💡 Need additional feedback ? start a PR chat

[nvborisenko]

This is very good! Nice catch!

[RenderMichael]

In the short-term, this should stop all the JSON failures people may be having.

In the long-term, this defeats some the purpose of source-generation. It's still faster, better, future-proof, etc. but it makes the AOT support "best effort". Instead, we may need separate overloads for the methods that take Dictionary<string, object> as parameters. We can expose an overload that takes a JsonNode parameter for those that want to guarantee AOT support.

We can also add an extra parameter of JsonTypeInfo<Dictionary<string, object>> for users to provide their own type info, for the same goal.

Either way, the Dictionary<string, object> parameters can never truly be AOT-safe

[nvborisenko]

Short-term: this PR is very good for regular users (99%), for AOT let's review each particular case (if it happens).
Long-term: "classic" commands/responses might be forwarded to BiDi implementation (strongly-typed).

[RenderMichael]

AOT is music to my ears :) One day this project can have the <IsAotCompatible>true</IsAotCompatible> property and will work fully.

I made another small PR as part of incremental progress #14733

[nvborisenko]

Very good drug from headache!