using Sbroenne.ExcelMcp.Service;
using Xunit;
namespace Sbroenne.ExcelMcp.CLI.Tests.Unit;
/// <summary>
/// Unit tests for ExcelMcpService error handling.
///
/// REGRESSION TESTS for Bug 5 (GitHub #482): Top-level exception catch in ProcessAsync
/// only included ex.Message, losing the exception type. This makes debugging impossible
/// when the same message text is shared by multiple exception types.
/// </summary>
[Trait("Layer", "Service")]
[Trait("Category", "Unit")]
[Trait("Feature", "ExcelMcpService")]
[Trait("Speed", "Fast")]
public sealed class ExcelMcpServiceErrorTests
{
/// <summary>
/// REGRESSION TEST for Bug 5 (#482): When an unexpected exception escapes
/// the ProcessAsync routing switch (e.g. NullReferenceException on null Command),
/// the error message must include the exception type name so the caller can
/// distinguish different failure modes.
/// </summary>
[Fact]
public async Task ProcessAsync_UnexpectedExceptionEscapesRouter_ErrorMessageIncludesTypeName()
{
// Arrange
using var service = new ExcelMcpService();
// null Command triggers NullReferenceException in parts = request.Command.Split(...)
// This exercises the top-level catch (Exception ex) block in ProcessAsync
#pragma warning disable CS8714 // required property set to null intentionally to trigger NRE
var request = new ServiceRequest { Command = null! };
#pragma warning restore CS8714
// Act
var response = await service.ProcessAsync(request);
// Assert
Assert.False(response.Success);
Assert.NotNull(response.ErrorMessage);
// REGRESSION: Before fix, only ex.Message was returned ("Object reference not set...").
// After fix, the type name is prepended: "NullReferenceException: Object reference..."
Assert.Contains("NullReferenceException", response.ErrorMessage,
StringComparison.OrdinalIgnoreCase);
}
/// <summary>
/// Verifies that normal error responses (business logic, not unexpected exceptions)
/// still work correctly after the Bug 5 fix. The format change should only affect
/// the top-level unexpected exception handler.
/// </summary>
[Fact]
public async Task ProcessAsync_UnknownCategory_ReturnsNormalErrorWithoutTypeName()
{
// Arrange
using var service = new ExcelMcpService();
var request = new ServiceRequest { Command = "unknowncategory.someaction" };
// Act
var response = await service.ProcessAsync(request);
// Assert
Assert.False(response.Success);
Assert.NotNull(response.ErrorMessage);
Assert.Contains("Unknown command category", response.ErrorMessage, StringComparison.OrdinalIgnoreCase);
// This path returns a normal string, not an exception-caught message,
// so it should NOT contain an exception type name prefix.
Assert.DoesNotContain("Exception:", response.ErrorMessage, StringComparison.OrdinalIgnoreCase);
}
/// <summary>
/// Verifies that the WithSessionAsync exception handler (the catch at the bottom
/// of ProcessAsync, covering session-level operations) also includes the type name.
/// </summary>
[Fact]
public async Task ProcessAsync_SessionCommandWithInvalidSessionId_ReturnsUsableError()
{
// Arrange
using var service = new ExcelMcpService();
// Send a sheet.list command with a session ID that doesn't exist
var request = new ServiceRequest
{
Command = "sheet.list",
SessionId = "nonexistent-session-id-00000000"
};
// Act
var response = await service.ProcessAsync(request);
// Assert — should fail gracefully with a descriptive message, not an unhandled exception
Assert.False(response.Success);
Assert.NotNull(response.ErrorMessage);
Assert.NotEmpty(response.ErrorMessage);
}
}
