Fix AVM module-not-found returning HTTP 422 instead of 400

[liuwuliuyun]

What does this PR do?

Fixes AvmDocsService.GetVersionsAsync and GetDocumentationAsync throwing InvalidOperationException when a module name is not found, which BaseCommand.GetStatusCode mapped to HTTP 422 (Unprocessable Entity). Since an invalid user-supplied module name is bad input rather than a configuration error, the exception type is changed to ArgumentException, which maps to HTTP 400 (Bad Request).

Changes

• AvmDocsService.cs: Changed both "module not found" throws from InvalidOperationException to ArgumentException with proper nameof(moduleName) parameter
• AvmVersionListCommandTests.cs / AvmDocumentationGetCommandTests.cs: Updated test mocks to throw ArgumentException to match the new service behavior

GitHub issue number

N/A — discovered during troubleshooting of HTTP 422 System.InvalidOperationException at AvmDocsService.GetVersionsAsync

Pre-merge Checklist

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[Copilot]

Pull request overview

This PR adjusts Azure Terraform AVM documentation/version lookup to treat an unknown module name as invalid user input by throwing ArgumentException (HTTP 400) instead of InvalidOperationException (HTTP 422), and updates unit tests and server changelog accordingly.

Changes:

• Changed AVM “module not found” exceptions in AvmDocsService from InvalidOperationException to ArgumentException(nameof(moduleName)) to map to HTTP 400.
• Updated AVM command unit tests’ service mocks to throw ArgumentException to match the new service behavior.
• Added a changelog entry describing the HTTP status code fix.

Invoking Livetests

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Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
tools/Azure.Mcp.Tools.AzureTerraform/src/Services/AvmDocsService.cs	Reclassifies “module not found” as bad input via ArgumentException to produce HTTP 400.
tools/Azure.Mcp.Tools.AzureTerraform/tests/Azure.Mcp.Tools.AzureTerraform.Tests/AvmVersionListCommandTests.cs	Updates mocked exception type for the versions command test path.
tools/Azure.Mcp.Tools.AzureTerraform/tests/Azure.Mcp.Tools.AzureTerraform.Tests/AvmDocumentationGetCommandTests.cs	Updates mocked exception type for the documentation command test path.
servers/Azure.Mcp.Server/changelog-entries/yunliu1-fix-avm-module-not-found-status.yaml	Documents the bug fix in the server changelog pipeline.

Comments suppressed due to low confidence (2)

tools/Azure.Mcp.Tools.AzureTerraform/tests/Azure.Mcp.Tools.AzureTerraform.Tests/AvmVersionListCommandTests.cs:62

• This test is meant to validate the new HTTP mapping for a missing module, but it only asserts the response is not OK. Please assert the specific expected status code (BadRequest/400) when the service throws an ArgumentException so the regression to 422 can't slip back in.

            .ThrowsAsync(new ArgumentException("Module not found", "moduleName"));

        var response = await ExecuteCommandAsync("--module-name", "nonexistent-module");

        Assert.NotEqual(HttpStatusCode.OK, response.Status);

tools/Azure.Mcp.Tools.AzureTerraform/tests/Azure.Mcp.Tools.AzureTerraform.Tests/AvmDocumentationGetCommandTests.cs:65

• This test currently only checks that the response isn't OK, which doesn't validate the intended behavior change (ArgumentException -> HTTP 400). Please assert the specific expected status code (BadRequest/400) when GetDocumentationAsync throws ArgumentException.

            .ThrowsAsync(new ArgumentException("Module not found", "moduleName"));

        var response = await ExecuteCommandAsync("--module-name", "nonexistent", "--module-version", "1.0.0");

        Assert.NotEqual(HttpStatusCode.OK, response.Status);