w4c-workflows-api/w4c-workflows-api.Tests/NodeRequestBudgetTests.cs

using w4c_workflows.Services.Security;
using w4c_workflows.Services.Nodes;
using Xunit;

namespace w4c_workflows.Tests;

/// <summary>
/// Tests for the run-scoped outbound-request budget and response-size cap.
/// </summary>
public class NodeRequestBudgetTests
{
    [Fact]
    public void Reserves_until_the_cap_then_denies()
    {
        var policy = EgressTestData.Quota(o => o.MaxRequestsPerRun = 2);
        var state = new Dictionary<string, object?>();

        Assert.True(policy.TryReserveRequest(state, out var first));
        Assert.Equal(1, first);
        Assert.True(policy.TryReserveRequest(state, out var second));
        Assert.Equal(2, second);
        Assert.False(policy.TryReserveRequest(state, out var third));
        Assert.Equal(3, third);
    }

    [Fact]
    public void Zero_cap_means_unlimited_and_does_not_touch_state()
    {
        var policy = EgressTestData.Quota(o => o.MaxRequestsPerRun = 0);
        var state = new Dictionary<string, object?>();

        for (var i = 0; i < 1_000; i++)
            Assert.True(policy.TryReserveRequest(state, out _));

        Assert.Empty(state);
    }

    [Fact]
    public void Separate_runs_have_separate_budgets()
    {
        var policy = EgressTestData.Quota(o => o.MaxRequestsPerRun = 1);

        Assert.True(policy.TryReserveRequest(new Dictionary<string, object?>(), out _));
        Assert.True(policy.TryReserveRequest(new Dictionary<string, object?>(), out _));
    }

    [Fact]
    public void Counter_is_stored_under_the_documented_state_key()
    {
        var policy = EgressTestData.Quota(o => o.MaxRequestsPerRun = 5);
        var state = new Dictionary<string, object?>();

        policy.TryReserveRequest(state, out _);

        Assert.True(state.ContainsKey(NodeRequestBudget.RequestCounterKey));
    }

    [Fact]
    public void Response_limit_is_inclusive()
    {
        var capped = EgressTestData.Quota(o => o.MaxResponseBytes = 10);

        Assert.True(capped.IsResponseWithinLimit(0));
        Assert.True(capped.IsResponseWithinLimit(10));
        Assert.False(capped.IsResponseWithinLimit(11));
    }

    [Fact]
    public void Zero_response_limit_is_unlimited()
    {
        var unlimited = EgressTestData.Quota(o => o.MaxResponseBytes = 0);

        Assert.True(unlimited.IsResponseWithinLimit(long.MaxValue));
    }
}