[dotnet] Annotate nullability on interactions

[RenderMichael]

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Description

Annotates nullability on interactions. The last type not annotated is the big Actions one.

Motivation and Context

Contributes to #14640

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

• Annotated nullability across multiple files in the dotnet project.

• Improved code safety with ArgumentNullException checks.

• Refactored properties to use expression-bodied members.

• Marked private fields as readonly where applicable.

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Changes walkthrough 📝

Relevant files

Enhancement

ElementCoordinates.cs Annotate nullability and refactor `ElementCoordinates`.    dotnet/src/webdriver/ElementCoordinates.cs Enabled nullable reference types. Added ArgumentNullException for constructor parameter. Refactored properties to use expression-bodied members. Marked element field as readonly. +9/-22    ActionSequence.cs Annotate nullability and refactor `ActionSequence`.            dotnet/src/webdriver/Interactions/ActionSequence.cs Enabled nullable reference types. Added ArgumentNullException for constructor parameter. Refactored properties to use expression-bodied members. Marked interactions field as readonly. +6/-12    IAction.cs Enable nullable reference types in `IAction`.                        dotnet/src/webdriver/Interactions/IAction.cs Enabled nullable reference types. +2/-0      ICoordinates.cs Enable nullable reference types in `ICoordinates`.              dotnet/src/webdriver/Interactions/ICoordinates.cs Enabled nullable reference types. +2/-0      InputDeviceKind.cs Enable nullable reference types in `InputDeviceKind`.        dotnet/src/webdriver/Interactions/InputDeviceKind.cs Enabled nullable reference types. +2/-0      Interaction.cs Annotate nullability and refactor `Interaction`.                  dotnet/src/webdriver/Interactions/Interaction.cs Enabled nullable reference types. Added ArgumentNullException for constructor parameter. Refactored properties to use expression-bodied members. Removed redundant private field sourceDevice. +5/-13    PauseInteraction.cs Annotate nullability and refactor `PauseInteraction`.        dotnet/src/webdriver/Interactions/PauseInteraction.cs Enabled nullable reference types. Marked duration field as readonly. +3/-1      WebElement.cs Annotate nullability and improve safety in `WebElement`.  dotnet/src/webdriver/WebElement.cs Enabled nullable reference types. Added ArgumentNullException for constructor parameter. +2/-1

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PR Reviewer Guide 🔍

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 Null Check The constructor checks for null id but not for null parentDriver parameter which could lead to NullReferenceException public WebElement(WebDriver parentDriver, string id) { this.driver = parentDriver; this.elementId = id ?? throw new ArgumentNullException(nameof(id)); } Type Safety Direct cast to IWebDriverObjectReference could throw InvalidCastException if element doesn't implement the interface return ((IWebDriverObjectReference)this.element).ObjectReferenceId;

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PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Score
Possible issue	Handle potential invalid type cast The cast to IWebDriverObjectReference could throw InvalidCastException if element is not of the expected type. Add a type check and handle the case when the cast fails. dotnet/src/webdriver/ElementCoordinates.cs [70] -return ((IWebDriverObjectReference)this.element).ObjectReferenceId; +if (this.element is IWebDriverObjectReference reference) + return reference.ObjectReferenceId; +throw new InvalidOperationException("Element does not implement IWebDriverObjectReference"); Apply this suggestion Suggestion importance[1-10]: 9 Why: The suggestion addresses a critical runtime safety issue by properly handling potential InvalidCastException, which could crash the application. The improved code provides better error handling and clearer error messages.	9
	Validate constructor parameter for null The constructor should validate that parentDriver is not null to prevent NullReferenceException in subsequent operations. dotnet/src/webdriver/WebElement.cs [52-56] public WebElement(WebDriver parentDriver, string id) { - this.driver = parentDriver; + this.driver = parentDriver ?? throw new ArgumentNullException(nameof(parentDriver)); this.elementId = id ?? throw new ArgumentNullException(nameof(id)); } Apply this suggestion Suggestion importance[1-10]: 8 Why: The suggestion prevents potential NullReferenceException by validating a critical constructor parameter. This is an important defensive programming practice that improves code reliability.	8

[RenderMichael]

element is WebElement, which implements IWebDriverObjectReference directly.

None of the implementations of ObjectReferenceId can return null (WebElement and ShadowRoot).

[RenderMichael]

id == null is unreachable here outside of users directly creating one. Adding this check here to enforce IWebDriverObjectReference.ObjectReferenceId never returning null.