dotnet add package Amazon.Lambda.Core
dotnet add package Amazon.Lambda.Serialization.SystemTextJson
dotnet add package Amazon.Lambda.TestUtilities    # NUnit-friendly mocks
dotnet add package Microsoft.NET.Test.Sdk
dotnet add package xunit

using Amazon.Lambda.Core;
using Amazon.Lambda.Serialization.SystemTextJson;

[assembly: LambdaSerializer(typeof(DefaultLambdaJsonSerializer))]

public class Functions
{
    public string Handler(string input, ILambdaContext context)
    {
        context.Logger.LogLine($"Got input: {input}");
        return input.ToUpper();
    }
}

using Amazon.Lambda.TestUtilities;
using Xunit;

public class FunctionsTests
{
    [Fact]
    public void Handler_Uppercases()
    {
        var functions = new Functions();
        var context = new TestLambdaContext
        {
            FunctionName = "test-fn",
            RemainingTime = TimeSpan.FromSeconds(30),
            // Logger is auto-set to TestLambdaLogger
        };

        var result = functions.Handler("hello", context);

        Assert.Equal("HELLO", result);
    }

    [Fact]
    public void Handler_LogsInput()
    {
        var functions = new Functions();
        var context = new TestLambdaContext();

        functions.Handler("hi", context);

        var logger = (TestLambdaLogger)context.Logger;
        Assert.Contains("Got input: hi", logger.Buffer.ToString());
    }
}

[Fact]
public void Handler_EarlyReturnsWhenTimeLow()
{
    var functions = new Functions();
    var context = new TestLambdaContext
    {
        RemainingTime = TimeSpan.FromSeconds(3)  // Below 5s threshold
    };

    var result = functions.Handler("work-that-takes-time", context);

    Assert.Contains("partial", result);
}

[Fact]
public void Handler_ParsesApiGatewayEvent()
{
    var json = File.ReadAllText("Events/apigw-request.json");
    var serializer = new DefaultLambdaJsonSerializer();
    var request = serializer.Deserialize<APIGatewayProxyRequest>(json);

    var functions = new Functions();
    var response = functions.HandleApi(request, new TestLambdaContext());

    Assert.Equal(200, response.StatusCode);
}

dotnet tool install -g Amazon.Lambda.Tools

dotnet lambda invoke-function MyFunction --payload '"hello"'

dotnet test

dotnet watch test

jobs:
  dotnet-lambda-tests:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v5
      - uses: actions/setup-dotnet@v4
        with: { dotnet-version: '8.0.x' }
      - run: dotnet restore
      - run: dotnet test --no-build --verbosity normal