.NET: Improve unit test coverage for Microsoft.Agents.AI.Anthropic

[Copilot]

Motivation and Context

Unit test coverage for Microsoft.Agents.AI.Anthropic was at 68.7%, below the 85% required threshold. Both AnthropicClientExtensions and AnthropicBetaServiceExtensions had uncovered branches in AsAIAgent methods.

Description

Added 12 new unit tests and improved assertions in existing tests to achieve 100% line and branch coverage for both extension classes.

New tests added (6 per extension class):

• CreateAIAgent_WithTools_AssignsToolsCorrectly
• CreateAIAgent_WithExplicitMaxTokens_UsesProvidedValue
• CreateAIAgent_WithToolsAndInstructions_AssignsBothCorrectly
• CreateAIAgent_WithEmptyTools_DoesNotAssignTools
• CreateAIAgent_WithNullInstructions_DoesNotSetInstructions
• CreateAIAgent_WithWhitespaceInstructions_DoesNotSetInstructions

Improved test assertions:

Tests now verify actual agent state rather than just checking creation succeeded:

// Before: only checked name
Assert.Equal("Test Agent", agent.Name);

// After: validates relevant properties
Assert.Equal("Test Agent", agent.Name);
Assert.Equal("Test instructions", agent.Instructions);
Assert.NotNull(agent.ChatClient);

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>.NET: Improve unit test coverage for Microsoft.Agents.AI.Anthropic</issue_title>
<issue_description>85% is the required level, coverage is currently at 68.7%

</issue_description>

<agent_instructions>Please analyze the Cobertura Coverage information related to the Microsoft.Agents.AI.Anthropic and lets improve its coverage on non-covered paths.

Please keep the same patterns used for UnitTests existing into the Microsoft.Agents.AI.Anthropic.UnitTests.

Use our repository guidelines regarding UnitTests code as well as use our existing File approach for the UnitTests generatino, only creating new ones if the file being covered have not being covered yet.

Ensure the coverage only covers non-covered paths without duplicating paths that are already covered.

Ensure all existing tests are working on top of the new added ones. This change should only be focused in UnitTests not changing any functionality.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes .NET: Improve unit test coverage for Microsoft.Agents.AI.Anthropic #3336

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[Copilot]

Pull request overview

This PR improves unit test coverage for the Microsoft.Agents.AI.Anthropic project, increasing it from 68.7% to 100% line and branch coverage. The changes address uncovered code paths in the AsAIAgent extension methods for both AnthropicClientExtensions and AnthropicBetaServiceExtensions.

Changes:

• Added 12 new unit tests (6 per extension class) covering previously untested branches in the AsAIAgent methods
• Improved existing test assertions to verify agent state more thoroughly

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
dotnet/tests/Microsoft.Agents.AI.Anthropic.UnitTests/Extensions/AnthropicClientExtensionsTests.cs	Added 6 new tests covering tools assignment, explicit max tokens, combined tools/instructions, empty tools, null instructions, and whitespace instructions scenarios. Added a CapturingHttpHandler helper class for testing HTTP requests.
dotnet/tests/Microsoft.Agents.AI.Anthropic.UnitTests/Extensions/AnthropicBetaServiceExtensionsTests.cs	Added identical 6 new tests for the Beta service extensions, covering the same scenarios as AnthropicClientExtensions. Added a CapturingHttpHandler helper class for testing HTTP requests.