TestLambdaLogger throws unexpectedly on LogError(Exception exception, string message, params object[] args)

[ambosch]

Describe the bug

I'm using the ILambdaLogger interface for structured logging in a Lambda Function. The method "LogError" is called in the code. A method that exists on the ILambdaLogger interface. The method overload in the code takes in the exception, a message, and the arguments referenced in the string. Example from what I do in my code:

´´´
logger.LogError(ex, "HTTP request failed. Status code: {statusCode}",
ex.StatusCode);
´´´

This corresponds to calling:

I tested throwing this exact Exception in my deployed function, and the logging works as expected. A structured log on JSON format is logged:

For unit testing, I use the TestLambdaLogger (that should implement the ILambdaLogger interface). I use XUnit. However, my tests unexpectedly throw on the call to the LogError line in the code above. Parts of the output:

I tested the method overload for LogError that takes in only one string. And that works, it does not throw.

So the problem seems to be that the TestLambdaLogger does not correctly implement the ILambdaLogger interface, as the method overload that works with the deployed function (and local invocation with sam), does not work when running the tests.

Regression Issue

• Select this option if this issue appears to be a regression.

Expected Behavior

This line:

´´´
logger.LogError(ex, "HTTP request failed. Status code: {statusCode}",
ex.StatusCode);
´´´

Should not throw for the TestLambdaLogger. It should just log the information in the console.

Current Behavior

The method fails with a stackoverflow exception.

Reproduction Steps

Run an XUnit test that uses the TestLambdaLogger from the TestLambdaContext.

Use this method from the ILambdaLogger interface in the code that is executed in the test:

    void LogError(Exception exception, string message, params object[] args)
    {
      this.Log(LogLevel.Error.ToString(), exception, message, args);
    }

The test will not complete, but give a stackoverflow error.

Possible Solution

No response

Additional Information/Context

Using JetBrains Rider

AWS .NET SDK and/or Package version used

Amazon.Lambda.TestUtilities 2.0.0
Amazon.Lambda.Core 2.5.1
Microsoft.NET.Test.Sdk 17.13.0
xunit 2.9.3
xunit.runner.visualstudio 3.0.2

Targeted .NET Platform

.NET 8.0.407

Operating System and version

macOS Sequoia

[ashishdhingra]

@ambosch Good afternoon. Could you please share sample XUnit Test project to reproduce the issue? The issue appears to be kind of reproducible using code below:

using Amazon.Lambda.Core;
using Amazon.Lambda.TestUtilities;
using static System.Runtime.InteropServices.JavaScript.JSType;

namespace LambdaXUnitTestProject
{
    public class UnitTest1
    {
        [Fact]
        public void TestLambdaFunction()
        {
            // Invoke the lambda function and confirm the string was upper cased.
            var function = new Function();
            var context = new TestLambdaContext()
            {
                FunctionName = "TestLambdafunction",
                Logger = new TestLambdaLogger()
            };

            var user = new User() { Name = "Test User", Email = "testemail@testdomain.com" };
            var result = function.FunctionHandler(user, context);

            Assert.True(result);
        }
    }

    public class Function
    {
        [Amazon.Lambda.Core.LambdaSerializer(typeof(Amazon.Lambda.Serialization.Json.JsonSerializer))]
        public bool FunctionHandler(User user, ILambdaContext lambdaContext)
        {
            Exception ex = new ArgumentException("ArugumentException");
            lambdaContext.Logger.LogError(ex, "Error occurred: {message}", ex.Message);

            return true;
        }
    }

    public class User
    {
        public string? Name { get; set; }
        public string? Email { get; set; }

        public override string ToString()
        {
            return $"{Name} ({Email})";
        }

    }
}

However, in this case I get Access violation exception.

Perhaps this also needs the similar fix implemented in PR #1872 for test tool.

Thanks,
Ashish

[ambosch]

Good morning @ashishdhingra , thank you for the quick follow-up.

The code you shared is quite similar to my code. However, in my test setup, only the internal method GetProducts is called. Without caring about the function handler being involved. Maybe that can be a distinguishing factor for which error is triggered? See the provided code.

Here is the test class and the relevant test, included the required setup.

using System.Net;
using Amazon.Lambda.TestUtilities;
using MyService.External;

namespace MyService.Test;

public class TestGetProducts
{
    [Fact]
    public async Task TestGetProductsUnauthorized()
    {
        var lambdaContext = new TestLambdaContext();
        var messageHandler = new MockHttpMessageHandler(
            new
            {
                message = "Unauthorized",
                code = 1001
            }, HttpStatusCode.Unauthorized);
        var httpClient = new HttpClient(messageHandler);
        var sut = new MyCustomHttpClient(httpClient);

        var result = await sut.GetProducts(lambdaContext.Logger);
        Assert.Equal([], result);
    }
}

Here is the definition of the MockHttpMessageHandler:

using System.Net;
using System.Net.Http.Json;

namespace MyService.Test;

public class MockHttpMessageHandler : HttpMessageHandler
{
    private readonly object? _response;
    private readonly HttpStatusCode _statusCode;

    public MockHttpMessageHandler(object? response = null,
        HttpStatusCode statusCode = HttpStatusCode.OK)
    {
        _response = response;
        _statusCode = statusCode;
    }


    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request,
        CancellationToken cancellationToken)
    {
        return new HttpResponseMessage
        {
            StatusCode = _statusCode,
            Content = JsonContent.Create(_response)
        };
    }
}

And here is the relevant part of the GetProducts method (which is what I want to test)

using System.Net.Http.Headers;
using System.Net.Http.Json;
using System.Text.Json;
using Amazon.Lambda.Core;
using MyService.Infrastructure.Utils;

namespace MyService.External;

public class MyCustomHttpClient
{
    private readonly HttpClient _httpClient;

    public MyCustomHttpClient(HttpClient httpClient)
    {
        _httpClient = httpClient;
        _httpClient.DefaultRequestHeaders.Accept.Clear();

        var apiCredentials = GetApiCredentials();
        _httpClient.BaseAddress =
            new Uri(apiCredentials.BaseUrl)
                .AddTrailingSlash();
        _httpClient.DefaultRequestHeaders.Authorization =
            new AuthenticationHeaderValue(apiCredentials
                .AuthorizationHeader);
    }

public async Task<ProductDto[]> GetProducts(ILambdaLogger logger)
    {
        try
        {
            using var response = await _httpClient.GetAsync("products");
            if (!response.IsSuccessStatusCode)
            {
                string responseString;
                try
                {
                    responseString = await response.Content.ReadAsStringAsync();
                }
                catch (Exception e)
                {
                    responseString = $"Could not read response from failed request: {e.Message}";
                }

                throw new
                    HttpRequestException( 
                        $"Failed HTTP GET /products request to the API. Response: {responseString}", null,
                        response.StatusCode);
            }
            
            ...

        }
        catch (HttpRequestException ex)
        {
            logger.LogError(ex, "HTTP request failed. Status code: {statusCode}",
                ex.StatusCode); // THIS IS THE LINE THAT THROWS

            return [];
        }

        ...

        catch (Exception ex)
        {
            logger.LogError($"Unknown exception: {ex.StackTrace}");
            return [];
        }
    }
}

Also, I did have a look at the PR you linked to this issue. Could you please provide more details about the fix you envision?

Thank you,

Regards Anne