[dotnet] Make the devtools SendCommand method AOT-safe

[RenderMichael]

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Description

This uses source-generated JSON serialization on more devtools-related types.

Motivation and Context

Contributes to #14480

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

Enhancement

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Description

• Introduced source-generated JSON serialization for DevTools types.

• Added JsonSerializerContext for improved serialization performance.

• Ignored DomMutationData.Element during JSON operations.

• Replaced generic serialization calls with context-specific serialization.

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Changes walkthrough 📝

Relevant files

Enhancement

DevToolsSession.cs Use context-specific JSON serialization in DevToolsSession dotnet/src/webdriver/DevTools/DevToolsSession.cs Replaced generic JSON serialization with context-specific serialization. Added DevToolsSessionSerializerContext for DevTools types. Improved logging and serialization performance. +7/-2      DomMutationData.cs Ignore `Element` property during JSON serialization            dotnet/src/webdriver/DomMutationData.cs Added JsonIgnore attribute to Element property. Prevented serialization of Element during JSON operations. +1/-0      JavaScriptEngine.cs Use context-specific JSON deserialization in JavaScriptEngine dotnet/src/webdriver/JavaScriptEngine.cs Replaced generic JSON deserialization with context-specific deserialization. Added JsonEngineSerializerContext for DomMutationData. +5/-1

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PR Reviewer Guide 🔍

(Review updated until commit de38b25)

Here are some key observations to aid the review process:

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

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Error Handling The JSON serialization/deserialization operations do not have explicit error handling. Consider adding try-catch blocks to handle potential serialization exceptions gracefully. string contents = JsonSerializer.Serialize(message, DevToolsSessionSerializerContext.Default.DevToolsCommandData); Null Check Missing null check for valueChangeData after deserialization before accessing its properties. This could lead to NullReferenceException if deserialization fails. var locator = By.CssSelector($"*[data-__webdriver_id='{valueChangeData.TargetId}']"); valueChangeData.Element = driver.FindElements(locator).FirstOrDefault();

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PR Code Suggestions ✨

Latest suggestions up to de38b25
Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	Add JSON serialization error handling Add error handling for JSON serialization to handle potential serialization exceptions that could occur during command serialization. dotnet/src/webdriver/DevTools/DevToolsSession.cs [287-289] -string contents = JsonSerializer.Serialize(message, DevToolsSessionSerializerContext.Default.DevToolsCommandData); -this.pendingCommands.TryAdd(message.CommandId, message); -await this.connection.SendData(contents).ConfigureAwait(false); +try { + string contents = JsonSerializer.Serialize(message, DevToolsSessionSerializerContext.Default.DevToolsCommandData); + this.pendingCommands.TryAdd(message.CommandId, message); + await this.connection.SendData(contents).ConfigureAwait(false); +} catch (JsonException ex) { + LogError("Failed to serialize DevTools command: {0}", ex.Message); + throw; +} Apply this suggestion Suggestion importance[1-10]: 8 __ Why: Adding error handling for JSON serialization is crucial for robustness, as serialization failures could occur with malformed data. The suggestion properly logs the error and maintains the exception chain.	Medium
	✅ Add null check after deserialization Suggestion Impact: The commit implements null safety check for DomMutationData but in a different way - using null-coalescing operator with throw instead of an if-check code diff: + DomMutationData valueChangeData = JsonSerializer.Deserialize(e.Payload, JsonEngineSerializerContext.Default.DomMutationData) ?? throw new JsonException("DomMutationData returned null"); Add null check for the deserialized DomMutationData before accessing its properties to prevent potential NullReferenceException. dotnet/src/webdriver/JavaScriptEngine.cs [402-403] DomMutationData valueChangeData = JsonSerializer.Deserialize(e.Payload, JsonEngineSerializerContext.Default.DomMutationData); +if (valueChangeData == null) { + return; +} var locator = By.CssSelector($"*[data-__webdriver_id='{valueChangeData.TargetId}']"); Apply this suggestion Suggestion importance[1-10]: 7 __ Why: The suggestion adds important null-safety check to prevent NullReferenceException when deserialization fails. This is a critical defensive programming practice for handling potentially invalid JSON data.	Medium
Learned best practice	✅ Add null validation checks before deserializing JSON data and accessing its properties to prevent NullReferenceExceptions Suggestion Impact: The commit added null validation for the versionInfo object after deserialization using null coalescing operator and exception throwing code diff: + var versionInfo = JsonSerializer.Deserialize(rawVersionInfo, DevToolsSessionSerializerContext.Default.DevToolsVersionInfo) ?? throw new JsonException("/json/version endpoint returned null response"); + this.EndpointAddress = versionInfo.WebSocketDebuggerUrl; Add null validation for rawVersionInfo before deserializing it to prevent potential NullReferenceException. Use ArgumentNullException.ThrowIfNull() to validate the input. dotnet/src/webdriver/DevTools/DevToolsSession.cs [414-415] +ArgumentNullException.ThrowIfNull(rawVersionInfo, nameof(rawVersionInfo)); var versionInfo = JsonSerializer.Deserialize(rawVersionInfo, DevToolsSessionSerializerContext.Default.DevToolsVersionInfo); +ArgumentNullException.ThrowIfNull(versionInfo, nameof(versionInfo)); this.websocketAddress = versionInfo.WebSocketDebuggerUrl; [Suggestion has been applied]	Low

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Previous suggestions

Suggestions up to commit 2d241d0

Category	Suggestion	Score
General	Add JSON serialization options The DevToolsSerializerContext should be marked with JsonSourceGenerationOptions to ensure consistent serialization behavior across the DevTools types. dotnet/src/webdriver/DevTools/Json/DevToolsJsonOptions.cs [37-40] [JsonSerializable(typeof(DevToolsCommandData))] [JsonSerializable(typeof(DevToolsVersionInfo))] [JsonSerializable(typeof(DomMutationData))] +[JsonSourceGenerationOptions(PropertyNamingPolicy = JsonKnownNamingPolicy.CamelCase)] internal sealed partial class DevToolsSerializerContext : JsonSerializerContext; Suggestion importance[1-10]: 7 Why: Adding JsonSourceGenerationOptions with CamelCase naming policy would ensure consistent JSON property naming across all DevTools types, improving the robustness of the serialization process and maintaining compatibility with the DevTools protocol.	7

[RenderMichael]

@nvborisenko re-opening this because of a remark I noticed in #13994:

We'll still allow access to lower level CDP functionality (see #13990), but the high level approach will be removed.

This is the lower-level CDP functionality: sending string commandName + JsonNode parameters and getting back JsonElement? response. For that reason, this method will not be depreciated and should support AOT (minimal effort to do so, as this PR shows).

[RenderMichael]

I misunderstood which methods were staying and which ones were going after the CDP depreciation. This PR is no longer worthwhile.