git.stella-ops.org/tests/StellaOps.Router.Gateway.Tests/LimitInheritanceResolverTests.cs

using FluentAssertions;
using StellaOps.Router.Gateway.RateLimit;
using Xunit;

namespace StellaOps.Router.Gateway.Tests;

public sealed class LimitInheritanceResolverTests
{
    [Fact]
    public void ResolveEnvironmentTarget_UsesEnvironmentDefaultsWhenNoMicroserviceOverride()
    {
        var config = new RateLimitConfig
        {
            ActivationThresholdPer5Min = 0,
            ForEnvironment = new EnvironmentLimitsConfig
            {
                ValkeyConnection = "localhost:6379",
                ValkeyBucket = "bucket",
                Rules = [new RateLimitRule { PerSeconds = 60, MaxRequests = 600 }],
            }
        }.Validate();

        var resolver = new LimitInheritanceResolver(config);
        var target = resolver.ResolveEnvironmentTarget("scanner", "/api/scans");

        target.Enabled.Should().BeTrue();
        target.Kind.Should().Be(RateLimitTargetKind.EnvironmentDefault);
        target.RouteName.Should().BeNull();
        target.TargetKey.Should().Be("scanner");
        target.Rules.Should().ContainSingle();
        target.Rules[0].PerSeconds.Should().Be(60);
        target.Rules[0].MaxRequests.Should().Be(600);
    }

    [Fact]
    public void ResolveEnvironmentTarget_UsesMicroserviceOverrideWhenPresent()
    {
        var config = new RateLimitConfig
        {
            ActivationThresholdPer5Min = 0,
            ForEnvironment = new EnvironmentLimitsConfig
            {
                ValkeyConnection = "localhost:6379",
                ValkeyBucket = "bucket",
                Rules = [new RateLimitRule { PerSeconds = 60, MaxRequests = 600 }],
                Microservices = new Dictionary<string, MicroserviceLimitsConfig>(StringComparer.OrdinalIgnoreCase)
                {
                    ["scanner"] = new MicroserviceLimitsConfig
                    {
                        Rules = [new RateLimitRule { PerSeconds = 10, MaxRequests = 1 }],
                    }
                }
            }
        }.Validate();

        var resolver = new LimitInheritanceResolver(config);
        var target = resolver.ResolveEnvironmentTarget("scanner", "/api/scans");

        target.Enabled.Should().BeTrue();
        target.Kind.Should().Be(RateLimitTargetKind.Microservice);
        target.RouteName.Should().BeNull();
        target.TargetKey.Should().Be("scanner");
        target.Rules.Should().ContainSingle();
        target.Rules[0].PerSeconds.Should().Be(10);
        target.Rules[0].MaxRequests.Should().Be(1);
    }

    [Fact]
    public void ResolveEnvironmentTarget_DisablesWhenNoRulesAtAnyLevel()
    {
        var config = new RateLimitConfig
        {
            ActivationThresholdPer5Min = 0,
            ForEnvironment = new EnvironmentLimitsConfig
            {
                ValkeyConnection = "localhost:6379",
                ValkeyBucket = "bucket",
            }
        }.Validate();

        var resolver = new LimitInheritanceResolver(config);
        var target = resolver.ResolveEnvironmentTarget("scanner", "/api/scans");

        target.Enabled.Should().BeFalse();
    }

    [Fact]
    public void ResolveEnvironmentTarget_UsesRouteOverrideWhenPresent()
    {
        var config = new RateLimitConfig
        {
            ActivationThresholdPer5Min = 0,
            ForEnvironment = new EnvironmentLimitsConfig
            {
                ValkeyConnection = "localhost:6379",
                ValkeyBucket = "bucket",
                Rules = [new RateLimitRule { PerSeconds = 60, MaxRequests = 600 }],
                Microservices = new Dictionary<string, MicroserviceLimitsConfig>(StringComparer.OrdinalIgnoreCase)
                {
                    ["scanner"] = new MicroserviceLimitsConfig
                    {
                        Rules = [new RateLimitRule { PerSeconds = 60, MaxRequests = 600 }],
                        Routes = new Dictionary<string, RouteLimitsConfig>(StringComparer.OrdinalIgnoreCase)
                        {
                            ["scan_submit"] = new RouteLimitsConfig
                            {
                                Pattern = "/api/scans",
                                MatchType = RouteMatchType.Exact,
                                Rules = [new RateLimitRule { PerSeconds = 300, MaxRequests = 1 }]
                            }
                        }
                    }
                }
            }
        }.Validate();

        var resolver = new LimitInheritanceResolver(config);
        var target = resolver.ResolveEnvironmentTarget("scanner", "/api/scans");

        target.Enabled.Should().BeTrue();
        target.Kind.Should().Be(RateLimitTargetKind.Route);
        target.RouteName.Should().Be("scan_submit");
        target.TargetKey.Should().Be("scanner:scan_submit");
        target.Rules.Should().ContainSingle();
        target.Rules[0].PerSeconds.Should().Be(300);
        target.Rules[0].MaxRequests.Should().Be(1);
    }

    [Fact]
    public void ResolveEnvironmentTarget_DoesNotTreatRouteAsOverrideWhenItHasNoRules()
    {
        var config = new RateLimitConfig
        {
            ActivationThresholdPer5Min = 0,
            ForEnvironment = new EnvironmentLimitsConfig
            {
                ValkeyConnection = "localhost:6379",
                ValkeyBucket = "bucket",
                Rules = [new RateLimitRule { PerSeconds = 60, MaxRequests = 600 }],
                Microservices = new Dictionary<string, MicroserviceLimitsConfig>(StringComparer.OrdinalIgnoreCase)
                {
                    ["scanner"] = new MicroserviceLimitsConfig
                    {
                        Rules = [new RateLimitRule { PerSeconds = 60, MaxRequests = 600 }],
                        Routes = new Dictionary<string, RouteLimitsConfig>(StringComparer.OrdinalIgnoreCase)
                        {
                            ["named_only"] = new RouteLimitsConfig
                            {
                                Pattern = "/api/scans",
                                MatchType = RouteMatchType.Exact
                            }
                        }
                    }
                }
            }
        }.Validate();

        var resolver = new LimitInheritanceResolver(config);
        var target = resolver.ResolveEnvironmentTarget("scanner", "/api/scans");

        target.Enabled.Should().BeTrue();
        target.Kind.Should().Be(RateLimitTargetKind.Microservice);
        target.RouteName.Should().BeNull();
        target.TargetKey.Should().Be("scanner");
    }
}