UA-.NETStandard/tests/Opc.Ua.Core.Tests/Stack/Client/RetryAfterHintTests.cs

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using System;
using NUnit.Framework;

namespace Opc.Ua.Core.Tests.Stack.Client
{
    [TestFixture]
    [Category("Client")]
    public sealed class RetryAfterHintTests
    {
        [Test]
        public void ParseServerRetryAfterReadsToken()
        {
            Assert.That(
                RetryAfterHint.ParseServerRetryAfter("RetryAfterMs=2000"),
                Is.EqualTo(TimeSpan.FromSeconds(2)));
        }

        [Test]
        public void ParseServerRetryAfterReadsEmbeddedToken()
        {
            Assert.That(
                RetryAfterHint.ParseServerRetryAfter(
                    "The server is too busy to accept a connection. RetryAfterMs=1500."),
                Is.EqualTo(TimeSpan.FromMilliseconds(1500)));
        }

        [Test]
        public void ParseServerRetryAfterReturnsNullWhenAbsent()
        {
            Assert.That(RetryAfterHint.ParseServerRetryAfter(null), Is.Null);
            Assert.That(RetryAfterHint.ParseServerRetryAfter(string.Empty), Is.Null);
            Assert.That(RetryAfterHint.ParseServerRetryAfter("no hint here"), Is.Null);
        }

        [Test]
        public void ParseServerRetryAfterReturnsNullForZeroOrMissingDigits()
        {
            Assert.That(RetryAfterHint.ParseServerRetryAfter("RetryAfterMs=0"), Is.Null);
            Assert.That(RetryAfterHint.ParseServerRetryAfter("RetryAfterMs=."), Is.Null);
        }

        [Test]
        public void ParseServerRetryAfterCapsPathologicalHint()
        {
            Assert.That(
                RetryAfterHint.ParseServerRetryAfter("RetryAfterMs=999999999999"),
                Is.EqualTo(RetryAfterHint.MaxRetryAfter));
        }

        [Test]
        public void ParseServerBusyRetryAfterReadsUaTcpErrorReason()
        {
            const string reason = "Server overloaded. RetryAfterMs=2500.";
            var result = new ServiceResult(
                null,
                StatusCodes.BadTcpServerTooBusy,
                LocalizedText.From($"Error received from remote host: {reason}"),
                reason);

            Assert.That(
                RetryAfterHint.ParseServerBusyRetryAfter(result),
                Is.EqualTo(TimeSpan.FromMilliseconds(2500)));
        }

        [Test]
        public void ParseServerBusyRetryAfterReadsBadServerTooBusy()
        {
            var result = new ServiceResult(
                null,
                StatusCodes.BadServerTooBusy,
                LocalizedText.From("RetryAfterMs=3000"),
                default(string));

            Assert.That(
                RetryAfterHint.ParseServerBusyRetryAfter(result),
                Is.EqualTo(TimeSpan.FromSeconds(3)));
        }

        [Test]
        public void ParseServerBusyRetryAfterIgnoresNonBusyStatus()
        {
            var result = new ServiceResult(
                null,
                StatusCodes.BadTcpInternalError,
                LocalizedText.From("RetryAfterMs=3000"),
                "RetryAfterMs=3000");

            Assert.That(RetryAfterHint.ParseServerBusyRetryAfter(result), Is.Null);
        }

        [Test]
        public void ParseServerBusyRetryAfterReadsNestedUaTcpErrorReason()
        {
            const string reason = "Server overloaded. RetryAfterMs=4000.";
            var inner = new ServiceResult(
                null,
                StatusCodes.BadTcpServerTooBusy,
                LocalizedText.From($"Error received from remote host: {reason}"),
                reason);
            var result = new ServiceResult(StatusCodes.BadSecureChannelClosed, inner);

            Assert.That(
                RetryAfterHint.ParseServerBusyRetryAfter(result),
                Is.EqualTo(TimeSpan.FromSeconds(4)));
        }

        [Test]
        public void ApplyReconnectDelayLowerBoundHonorsHint()
        {
            var policy = new ExponentialBackoffChannelReconnectPolicy
            {
                MinDelay = TimeSpan.FromMilliseconds(500),
                MaxDelay = TimeSpan.FromSeconds(30)
            };

            TimeSpan delay = RetryAfterHint.ApplyReconnectDelayLowerBound(
                policy,
                policy.GetDelay(0),
                TimeSpan.FromSeconds(2));

            Assert.That(delay, Is.EqualTo(TimeSpan.FromSeconds(2)));
        }

        [Test]
        public void ApplyReconnectDelayLowerBoundClampsHintToPolicyMaximum()
        {
            var policy = new ExponentialBackoffChannelReconnectPolicy
            {
                MinDelay = TimeSpan.FromMilliseconds(500),
                MaxDelay = TimeSpan.FromSeconds(5)
            };

            TimeSpan delay = RetryAfterHint.ApplyReconnectDelayLowerBound(
                policy,
                policy.GetDelay(0),
                TimeSpan.FromSeconds(30));

            Assert.That(delay, Is.EqualTo(TimeSpan.FromSeconds(5)));
        }
    }
}