Shared API's V2 (#289)

Added V2 Shared API's infrastructure
Added request coalescing
Added rate limiting admission logic
Fixed some rate limiting issues

CryptoExchange.Net.UnitTests/RateLimitTests.cs

@@ -3,6 +3,7 @@ using CryptoExchange.Net.RateLimiting;
 using CryptoExchange.Net.RateLimiting.Filters;
 using CryptoExchange.Net.RateLimiting.Guards;
 using CryptoExchange.Net.RateLimiting.Interfaces;
+using CryptoExchange.Net.RateLimiting.Trackers;
 using CryptoExchange.Net.UnitTests.Implementations;
 using NUnit.Framework;
 using System;
@@ -33,12 +34,12 @@ namespace CryptoExchange.Net.UnitTests
 
             for (var i = 0; i < requests + 1; i++)
             {
-                var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition, "123", 1, RateLimitingBehaviour.Wait, null, default);
+                var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition, "123", 1, RateLimitingBehaviour.Wait, null, 1, default);
                 Assert.That(i == requests ? triggered : !triggered);
             }
             triggered = false;
             await Task.Delay((int)Math.Round(perSeconds * 1000) + 10);
-            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition, "123", 1, RateLimitingBehaviour.Wait, null, default);
+            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition, "123", 1, RateLimitingBehaviour.Wait, null, 1, default);
             Assert.That(!triggered);
         }
 
@@ -58,7 +59,7 @@ namespace CryptoExchange.Net.UnitTests
             rateLimiter.RateLimitTriggered += (x) => { evnt = x; };
             for (var i = 0; i < 2; i++)
             {
-                var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition, "123", 1, RateLimitingBehaviour.Wait, null, default);
+                var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition, "123", 1, RateLimitingBehaviour.Wait, null, 1, default);
                 bool expected = i == 1 ? expectLimiting ? evnt?.DelayTime > TimeSpan.Zero : evnt == null : evnt == null;
                 Assert.That(expected);
             }
@@ -79,9 +80,9 @@ namespace CryptoExchange.Net.UnitTests
             RateLimitEvent? evnt = null;
             rateLimiter.RateLimitTriggered += (x) => { evnt = x; };
 
-            var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition1, "123", 1, RateLimitingBehaviour.Wait, null, default);
+            var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition1, "123", 1, RateLimitingBehaviour.Wait, null, 1, default);
             Assert.That(evnt == null);
-            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition2, "123", 1, RateLimitingBehaviour.Wait, null, default);
+            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition2, "123", 1, RateLimitingBehaviour.Wait, null, 1, default);
             Assert.That(expectLimiting ? evnt != null : evnt == null);
         }
 
@@ -100,12 +101,12 @@ namespace CryptoExchange.Net.UnitTests
 
             for (var i = 0; i < requests + 1; i++)
             {
-                var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition, "123", 1, RateLimitingBehaviour.Wait, null, default);
+                var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition, "123", 1, RateLimitingBehaviour.Wait, null, 1, default);
                 Assert.That(i == requests ? triggered : !triggered);
             }
             triggered = false;
             await Task.Delay((int)Math.Round(perSeconds * 1000) + 10);
-            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition, "123", 1, RateLimitingBehaviour.Wait, null, default);
+            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition, "123", 1, RateLimitingBehaviour.Wait, null, 1, default);
             Assert.That(!triggered);
         }
 
@@ -123,7 +124,7 @@ namespace CryptoExchange.Net.UnitTests
             rateLimiter.RateLimitTriggered += (x) => { evnt = x; };
             for (var i = 0; i < 2; i++)
             {
-                var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition, "123", 1, RateLimitingBehaviour.Wait, null, default);
+                var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition, "123", 1, RateLimitingBehaviour.Wait, null, 1, default);
                 bool expected = i == 1 ? expectLimited ? evnt?.DelayTime > TimeSpan.Zero : evnt == null : evnt == null;
                 Assert.That(expected);
             }
@@ -143,7 +144,7 @@ namespace CryptoExchange.Net.UnitTests
             rateLimiter.RateLimitTriggered += (x) => { evnt = x; };
             for (var i = 0; i < 2; i++)
             {
-                var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition, "123", 1, RateLimitingBehaviour.Wait, null, default);
+                var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition, "123", 1, RateLimitingBehaviour.Wait, null, 1, default);
                 bool expected = i == 1 ? expectLimited ? evnt?.DelayTime > TimeSpan.Zero : evnt == null : evnt == null;
                 Assert.That(expected);
             }
@@ -166,9 +167,9 @@ namespace CryptoExchange.Net.UnitTests
             RateLimitEvent? evnt = null;
             rateLimiter.RateLimitTriggered += (x) => { evnt = x; };
 
-            var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition1, key1, 1, RateLimitingBehaviour.Wait, null, default);
+            var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition1, key1, 1, RateLimitingBehaviour.Wait, null, 1, default);
             Assert.That(evnt == null);
-            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition2, key2, 1, RateLimitingBehaviour.Wait, null, default);
+            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition2, key2, 1, RateLimitingBehaviour.Wait, null, 1, default);
             Assert.That(expectLimited ? evnt != null : evnt == null);
         }
 
@@ -185,9 +186,9 @@ namespace CryptoExchange.Net.UnitTests
             RateLimitEvent? evnt = null;
             rateLimiter.RateLimitTriggered += (x) => { evnt = x; };
 
-            var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition1, "123", 1, RateLimitingBehaviour.Wait, null, default);
+            var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition1, "123", 1, RateLimitingBehaviour.Wait, null, 1, default);
             Assert.That(evnt == null);
-            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition2, null, 1, RateLimitingBehaviour.Wait, null, default);
+            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition2, null, 1, RateLimitingBehaviour.Wait, null, 1, default);
             Assert.That(expectLimited ? evnt != null : evnt == null);
         }
 
@@ -205,9 +206,9 @@ namespace CryptoExchange.Net.UnitTests
             RateLimitEvent? evnt = null;
             rateLimiter.RateLimitTriggered += (x) => { evnt = x; };
 
-            var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition1, "123", 1, RateLimitingBehaviour.Wait, null, default);
+            var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition1, "123", 1, RateLimitingBehaviour.Wait, null, 1, default);
             Assert.That(evnt == null);
-            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition2, "123", 1, RateLimitingBehaviour.Wait, null, default);
+            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, requestDefinition2, "123", 1, RateLimitingBehaviour.Wait, null, 1, default);
             Assert.That(expectLimited ? evnt != null : evnt == null);
         }
 
@@ -222,9 +223,9 @@ namespace CryptoExchange.Net.UnitTests
             RateLimitEvent? evnt = null;
             rateLimiter.RateLimitTriggered += (x) => { evnt = x; };
 
-            var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Connection, new RequestDefinition(host1, "1", HttpMethod.Get), "123", 1, RateLimitingBehaviour.Wait, null, default);
+            var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Connection, new RequestDefinition(host1, "1", HttpMethod.Get), "123", 1, RateLimitingBehaviour.Wait, null, 1, default);
             Assert.That(evnt == null);
-            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Connection, new RequestDefinition(host2, "1", HttpMethod.Get), "123", 1, RateLimitingBehaviour.Wait, null, default);
+            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Connection, new RequestDefinition(host2, "1", HttpMethod.Get), "123", 1, RateLimitingBehaviour.Wait, null, 1, default);
             Assert.That(expectLimited ? evnt != null : evnt == null);
         }
 
@@ -238,8 +239,8 @@ namespace CryptoExchange.Net.UnitTests
             rateLimiter.RateLimitTriggered += (x) => { evnt = x; };
             var ct = new CancellationTokenSource(TimeSpan.FromSeconds(0.2));
 
-            var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Connection, new RequestDefinition("https://test.com", "1", HttpMethod.Get), "123", 1, RateLimitingBehaviour.Wait, null, ct.Token);
-            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Connection, new RequestDefinition("https://test.com", "1", HttpMethod.Get), "123", 1, RateLimitingBehaviour.Wait, null, ct.Token);
+            var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Connection, new RequestDefinition("https://test.com", "1", HttpMethod.Get), "123", 1, RateLimitingBehaviour.Wait, null, 1, ct.Token);
+            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Connection, new RequestDefinition("https://test.com", "1", HttpMethod.Get), "123", 1, RateLimitingBehaviour.Wait, null, 1, ct.Token);
             Assert.That(result2.Error, Is.TypeOf<CancellationRequestedError>());
         }
 
@@ -257,9 +258,9 @@ namespace CryptoExchange.Net.UnitTests
             var ct = new CancellationTokenSource(TimeSpan.FromSeconds(0.2));
 
             // act
-            var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, definition, null, 1, RateLimitingBehaviour.Fail, null, ct.Token);
+            var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, definition, null, 1, RateLimitingBehaviour.Fail, null, 1, ct.Token);
             await rateLimiter.ResetAsync(RateLimitItemType.Request, definition, null, null, null, default);
-            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, definition, null, 1, RateLimitingBehaviour.Fail, null, ct.Token);
+            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, definition, null, 1, RateLimitingBehaviour.Fail, null, 1, ct.Token);
             
             // assert
             Assert.That(evnt, Is.Null);
@@ -279,10 +280,10 @@ namespace CryptoExchange.Net.UnitTests
             rateLimiter.RateLimitTriggered += (x) => { evnt = x; };
 
             // act
-            var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, definition1, null, 1, RateLimitingBehaviour.Fail, null, default);
-            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, definition2, null, 1, RateLimitingBehaviour.Fail, null, default);
+            var result1 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, definition1, null, 1, RateLimitingBehaviour.Fail, null, 1, default);
+            var result2 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, definition2, null, 1, RateLimitingBehaviour.Fail, null, 1, default);
             await rateLimiter.ResetAsync(RateLimitItemType.Request, definition1, null, null, null, default);
-            var result3 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, definition2, null, 1, RateLimitingBehaviour.Fail, null, default);
+            var result3 = await rateLimiter.ProcessAsync(new TraceLogger(), 1, RateLimitItemType.Request, definition2, null, 1, RateLimitingBehaviour.Fail, null, 1, default);
             
             // assert
             Assert.That(evnt, Is.Not.Null);
@@ -321,5 +322,73 @@ namespace CryptoExchange.Net.UnitTests
             // assert
             Assert.That(evnt != null, Is.EqualTo(expectLimited));
         }
+
+        [TestCase(RateLimitWindowType.Fixed)]
+        [TestCase(RateLimitWindowType.FixedAfterFirst)]
+        [TestCase(RateLimitWindowType.Sliding)]
+        [TestCase(RateLimitWindowType.Decay)]
+        public async Task LowerThreshold_ReservesCapacityForFullThreshold(RateLimitWindowType windowType)
+        {
+            var gate = new RateLimitGate("Test");
+            gate.AddGuard(new RateLimitGuard(
+                RateLimitGuard.PerHost,
+                new LimitItemTypeFilter(RateLimitItemType.Request),
+                10,
+                TimeSpan.FromHours(1),
+                windowType,
+                decayPerTimeSpan: 1));
+
+            var definition = new RequestDefinition(
+                "https://test.com", "/ticker", HttpMethod.Get);
+            var logger = new TraceLogger();
+
+            for (var i = 0; i < 8; i++)
+            {
+                var result = await gate.ProcessAsync(
+                    logger, i, RateLimitItemType.Request, definition, null, 1,
+                    RateLimitingBehaviour.Fail, null, 0.8, default);
+                Assert.That(result.Success, Is.True);
+            }
+
+            var marketData = await gate.ProcessAsync(
+                logger, 9, RateLimitItemType.Request, definition, null, 1,
+                RateLimitingBehaviour.Fail, null, 0.8, default);
+            Assert.That(marketData.Error, Is.TypeOf<ClientRateLimitError>());
+
+            var order = await gate.ProcessAsync(
+                logger, 10, RateLimitItemType.Request, definition, null, 2,
+                RateLimitingBehaviour.Fail, null, 1.0, default);
+            Assert.That(order.Success, Is.True);
+
+            var overHardLimit = await gate.ProcessAsync(
+                logger, 11, RateLimitItemType.Request, definition, null, 1,
+                RateLimitingBehaviour.Fail, null, 1.0, default);
+            Assert.That(overHardLimit.Error, Is.TypeOf<ClientRateLimitError>());
+        }
+
+        [TestCase(0.1, 10)]
+        [TestCase(1, 50)]
+        [TestCase(5, 250)]
+        [TestCase(60, 250)]
+        public void RateLimitSafetyMargin_DefaultIsProportionalAndCapped(double periodSeconds, int expectedMarginMilliseconds)
+        {
+            var margin = WindowTrackerHelpers.GetDefaultSafetyMargin(TimeSpan.FromSeconds(periodSeconds));
+
+            Assert.That(margin, Is.EqualTo(TimeSpan.FromMilliseconds(expectedMarginMilliseconds)));
+        }
+
+        [Test]
+        public void RateLimitGuard_ExplicitSafetyMarginIsUsed()
+        {
+            var guard = new RateLimitGuard(
+                RateLimitGuard.PerHost,
+                new LimitItemTypeFilter(RateLimitItemType.Request),
+                1,
+                TimeSpan.FromSeconds(1),
+                RateLimitWindowType.Sliding,
+                safetyMargin: TimeSpan.Zero);
+
+            Assert.That(guard.SafetyMargin, Is.EqualTo(TimeSpan.Zero));
+        }
     }
 }

CryptoExchange.Net.UnitTests/RequestCoalescerTests.cs

@@ -0,0 +1,281 @@
+using CryptoExchange.Net.Objects;
+using Microsoft.Extensions.Logging.Abstractions;
+using NUnit.Framework;
+using System;
+using System.Collections;
+using System.Reflection;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace CryptoExchange.Net.UnitTests
+{
+    [TestFixture]
+    public class RequestCoalescerTests
+    {
+        private static readonly TimeSpan _testTimeout = TimeSpan.FromSeconds(5);
+
+        [Test]
+        public async Task ExecuteAsync_WithIdenticalRequests_ShouldExecuteRequestOnce()
+        {
+            var coalescer = CreateCoalescer();
+            var key = CreateKey();
+            var requestCompletion = CreateCompletionSource<string>();
+            var requestStarted = CreateCompletionSource<bool>();
+            var requestCount = 0;
+
+            async Task<string> ExecuteRequest(CancellationToken cancellationToken)
+            {
+                Interlocked.Increment(ref requestCount);
+                requestStarted.TrySetResult(true);
+                return await requestCompletion.Task;
+            }
+
+            var first = coalescer.ExecuteAsync(key, ExecuteRequest, () => "canceled", CancellationToken.None);
+            await requestStarted.Task.WaitAsync(_testTimeout);
+            var second = coalescer.ExecuteAsync(key, ExecuteRequest, () => "canceled", CancellationToken.None);
+
+            Assert.That(requestCount, Is.EqualTo(1));
+
+            requestCompletion.SetResult("result");
+
+            Assert.That(await first.WaitAsync(_testTimeout), Is.EqualTo("result"));
+            Assert.That(await second.WaitAsync(_testTimeout), Is.EqualTo("result"));
+            Assert.That(requestCount, Is.EqualTo(1));
+        }
+
+        [Test]
+        public async Task ExecuteAsync_WithDifferentKeys_ShouldExecuteEachRequest()
+        {
+            var coalescer = CreateCoalescer();
+            var firstCompletion = CreateCompletionSource<string>();
+            var secondCompletion = CreateCompletionSource<string>();
+            var firstStarted = CreateCompletionSource<bool>();
+            var secondStarted = CreateCompletionSource<bool>();
+            var requestCount = 0;
+
+            var first = coalescer.ExecuteAsync(
+                CreateKey(parameters: "symbol=ETH"),
+                async cancellationToken =>
+                {
+                    Interlocked.Increment(ref requestCount);
+                    firstStarted.TrySetResult(true);
+                    return await firstCompletion.Task;
+                },
+                () => "canceled",
+                CancellationToken.None);
+
+            var second = coalescer.ExecuteAsync(
+                CreateKey(parameters: "symbol=BTC"),
+                async cancellationToken =>
+                {
+                    Interlocked.Increment(ref requestCount);
+                    secondStarted.TrySetResult(true);
+                    return await secondCompletion.Task;
+                },
+                () => "canceled",
+                CancellationToken.None);
+
+            await Task.WhenAll(firstStarted.Task, secondStarted.Task).WaitAsync(_testTimeout);
+            Assert.That(requestCount, Is.EqualTo(2));
+
+            firstCompletion.SetResult("first");
+            secondCompletion.SetResult("second");
+
+            Assert.That(await first.WaitAsync(_testTimeout), Is.EqualTo("first"));
+            Assert.That(await second.WaitAsync(_testTimeout), Is.EqualTo("second"));
+        }
+
+        [Test]
+        public async Task ExecuteAsync_WhenOneListenerCancels_ShouldKeepSharedRequestRunning()
+        {
+            var coalescer = CreateCoalescer();
+            var requestCompletion = CreateCompletionSource<string>();
+            var requestStarted = CreateCompletionSource<CancellationToken>();
+            var requestCount = 0;
+            using var firstCancellationSource = new CancellationTokenSource();
+
+            async Task<string> ExecuteRequest(CancellationToken cancellationToken)
+            {
+                Interlocked.Increment(ref requestCount);
+                requestStarted.TrySetResult(cancellationToken);
+                return await requestCompletion.Task;
+            }
+
+            var first = coalescer.ExecuteAsync(CreateKey(), ExecuteRequest, () => "canceled", firstCancellationSource.Token);
+            var requestCancellationToken = await requestStarted.Task.WaitAsync(_testTimeout);
+            var second = coalescer.ExecuteAsync(CreateKey(), ExecuteRequest, () => "canceled", CancellationToken.None);
+
+            firstCancellationSource.Cancel();
+
+            Assert.That(await first.WaitAsync(_testTimeout), Is.EqualTo("canceled"));
+            Assert.That(requestCancellationToken.IsCancellationRequested, Is.False);
+            Assert.That(requestCount, Is.EqualTo(1));
+
+            requestCompletion.SetResult("result");
+
+            Assert.That(await second.WaitAsync(_testTimeout), Is.EqualTo("result"));
+        }
+
+        [Test]
+        public async Task ExecuteAsync_WhenAllListenersCancel_ShouldCancelSharedRequest()
+        {
+            var coalescer = CreateCoalescer();
+            var requestStarted = CreateCompletionSource<bool>();
+            var requestCanceled = CreateCompletionSource<bool>();
+            using var firstCancellationSource = new CancellationTokenSource();
+            using var secondCancellationSource = new CancellationTokenSource();
+
+            async Task<string> ExecuteRequest(CancellationToken cancellationToken)
+            {
+                using (cancellationToken.Register(() => requestCanceled.TrySetResult(true)))
+                {
+                    requestStarted.TrySetResult(true);
+                    await requestCanceled.Task;
+                    return "request canceled";
+                }
+            }
+
+            var first = coalescer.ExecuteAsync(CreateKey(), ExecuteRequest, () => "listener canceled", firstCancellationSource.Token);
+            await requestStarted.Task.WaitAsync(_testTimeout);
+            var second = coalescer.ExecuteAsync(CreateKey(), ExecuteRequest, () => "listener canceled", secondCancellationSource.Token);
+
+            firstCancellationSource.Cancel();
+            Assert.That(await first.WaitAsync(_testTimeout), Is.EqualTo("listener canceled"));
+            Assert.That(requestCanceled.Task.IsCompleted, Is.False);
+
+            secondCancellationSource.Cancel();
+
+            Assert.That(await second.WaitAsync(_testTimeout), Is.EqualTo("listener canceled"));
+            Assert.That(await requestCanceled.Task.WaitAsync(_testTimeout), Is.True);
+        }
+
+        [Test]
+        public async Task ExecuteAsync_WithAlreadyCanceledListener_ShouldNotStartRequest()
+        {
+            var coalescer = CreateCoalescer();
+            var requestCount = 0;
+            using var cancellationSource = new CancellationTokenSource();
+            cancellationSource.Cancel();
+
+            var result = await coalescer.ExecuteAsync(
+                CreateKey(),
+                cancellationToken =>
+                {
+                    Interlocked.Increment(ref requestCount);
+                    return Task.FromResult("result");
+                },
+                () => "canceled",
+                cancellationSource.Token);
+
+            Assert.That(result, Is.EqualTo("canceled"));
+            Assert.That(requestCount, Is.Zero);
+        }
+
+        [Test]
+        public async Task ExecuteAsync_AfterRequestCompletes_ShouldStartNewRequest()
+        {
+            var coalescer = CreateCoalescer();
+            var requestCount = 0;
+
+            Task<int> ExecuteRequest(CancellationToken cancellationToken)
+                => Task.FromResult(Interlocked.Increment(ref requestCount));
+
+            var first = await coalescer.ExecuteAsync(CreateKey(typeof(int)), ExecuteRequest, () => -1, CancellationToken.None);
+            var second = await coalescer.ExecuteAsync(CreateKey(typeof(int)), ExecuteRequest, () => -1, CancellationToken.None);
+
+            Assert.That(first, Is.EqualTo(1));
+            Assert.That(second, Is.EqualTo(2));
+            Assert.That(requestCount, Is.EqualTo(2));
+        }
+
+        [Test]
+        public void ExecuteAsync_AfterRequestFails_ShouldStartNewRequest()
+        {
+            var coalescer = CreateCoalescer();
+            var requestCount = 0;
+
+            Task<string> ExecuteRequest(CancellationToken cancellationToken)
+            {
+                if (Interlocked.Increment(ref requestCount) == 1)
+                    return Task.FromException<string>(new InvalidOperationException("Request failed"));
+
+                return Task.FromResult("result");
+            }
+
+            Assert.ThrowsAsync<InvalidOperationException>(async () =>
+                await coalescer.ExecuteAsync(CreateKey(), ExecuteRequest, () => "canceled", CancellationToken.None));
+
+            Assert.That(
+                coalescer.ExecuteAsync(CreateKey(), ExecuteRequest, () => "canceled", CancellationToken.None).GetAwaiter().GetResult(),
+                Is.EqualTo("result"));
+            Assert.That(requestCount, Is.EqualTo(2));
+        }
+
+        [Test]
+        public async Task ExecuteAsync_WhenAbandonedRequestCompletes_ShouldNotRemoveReplacementRequest()
+        {
+            var coalescer = CreateCoalescer();
+            var key = CreateKey();
+            var oldRequestCompletion = CreateCompletionSource<string>();
+            var oldRequestStarted = CreateCompletionSource<bool>();
+            var replacementCompletion = CreateCompletionSource<string>();
+            var replacementStarted = CreateCompletionSource<bool>();
+            var requestCount = 0;
+            using var cancellationSource = new CancellationTokenSource();
+
+            async Task<string> ExecuteOldRequest(CancellationToken cancellationToken)
+            {
+                Interlocked.Increment(ref requestCount);
+                oldRequestStarted.TrySetResult(true);
+                return await oldRequestCompletion.Task;
+            }
+
+            async Task<string> ExecuteReplacementRequest(CancellationToken cancellationToken)
+            {
+                Interlocked.Increment(ref requestCount);
+                replacementStarted.TrySetResult(true);
+                return await replacementCompletion.Task;
+            }
+
+            var abandonedListener = coalescer.ExecuteAsync(key, ExecuteOldRequest, () => "canceled", cancellationSource.Token);
+            await oldRequestStarted.Task.WaitAsync(_testTimeout);
+            var oldPhysicalRequest = GetPhysicalRequest(coalescer, key);
+
+            cancellationSource.Cancel();
+            Assert.That(await abandonedListener.WaitAsync(_testTimeout), Is.EqualTo("canceled"));
+
+            var replacementListener = coalescer.ExecuteAsync(key, ExecuteReplacementRequest, () => "canceled", CancellationToken.None);
+            await replacementStarted.Task.WaitAsync(_testTimeout);
+
+            oldRequestCompletion.SetResult("old result");
+            await oldPhysicalRequest.WaitAsync(_testTimeout);
+
+            var joinedReplacementListener = coalescer.ExecuteAsync(key, ExecuteReplacementRequest, () => "canceled", CancellationToken.None);
+            Assert.That(requestCount, Is.EqualTo(2));
+
+            replacementCompletion.SetResult("replacement result");
+
+            Assert.That(await replacementListener.WaitAsync(_testTimeout), Is.EqualTo("replacement result"));
+            Assert.That(await joinedReplacementListener.WaitAsync(_testTimeout), Is.EqualTo("replacement result"));
+            Assert.That(requestCount, Is.EqualTo(2));
+        }
+
+        private static RequestCoalescer CreateCoalescer()
+            => new RequestCoalescer(NullLogger.Instance);
+
+        private static RequestCoalescingKey CreateKey(Type? responseType = null, string? parameters = null)
+            => new RequestCoalescingKey("GET", "https://localhost/test", parameters, responseType ?? typeof(string));
+
+        private static TaskCompletionSource<T> CreateCompletionSource<T>()
+            => new TaskCompletionSource<T>(TaskCreationOptions.RunContinuationsAsynchronously);
+
+        private static Task GetPhysicalRequest(RequestCoalescer coalescer, RequestCoalescingKey key)
+        {
+            var requestsField = typeof(RequestCoalescer).GetField("_requests", BindingFlags.Instance | BindingFlags.NonPublic)!;
+            var requests = (IDictionary)requestsField.GetValue(coalescer)!;
+            var entry = requests[key]!;
+            var requestProperty = entry.GetType().GetProperty("Request")!;
+            return ((Lazy<Task<object>>)requestProperty.GetValue(entry)!).Value;
+        }
+    }
+}

CryptoExchange.Net.UnitTests/SharedApiClientTests.cs

@@ -0,0 +1,355 @@
+using CryptoExchange.Net.Interfaces.Clients;
+using CryptoExchange.Net.RateLimiting;
+using CryptoExchange.Net.SharedApis;
+using Microsoft.Extensions.DependencyInjection;
+using NUnit.Framework;
+using System;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace CryptoExchange.Net.UnitTests
+{
+    [TestFixture]
+    internal class SharedApiClientTests
+    {
+        [Test]
+        public void GetCapability_ShouldUseCapabilityTradingModes()
+        {
+            var sharedApi = new TestSharedApi(
+                [TradingMode.Spot, TradingMode.PerpetualLinear],
+                [TradingMode.Spot]);
+            var client = new TestSharedApiClient(sharedApi);
+
+            Assert.Multiple(() =>
+            {
+                Assert.That(client.GetCapability<ITestCapability>(TradingMode.Spot)?.Capability, Is.SameAs(sharedApi));
+                Assert.That(client.GetCapability<ITestCapability>(TradingMode.PerpetualLinear), Is.Null);
+                Assert.That(client.GetCapabilities<ITestCapability>(TradingMode.Spot), Has.Count.EqualTo(1));
+                Assert.That(client.GetCapabilities<ITestCapability>(TradingMode.PerpetualLinear), Is.Empty);
+            });
+        }
+
+        [Test]
+        public void CapabilityTradingModes_ShouldDefaultToSharedApiTradingModes()
+        {
+            var sharedApi = new TestSharedApi(
+                [TradingMode.Spot, TradingMode.PerpetualLinear],
+                null);
+            var client = new TestSharedApiClient(sharedApi);
+
+            Assert.Multiple(() =>
+            {
+                Assert.That(client.GetCapability<ITestCapability>(TradingMode.Spot)?.Capability, Is.SameAs(sharedApi));
+                Assert.That(client.GetCapability<ITestCapability>(TradingMode.PerpetualLinear)?.Capability, Is.SameAs(sharedApi));
+            });
+        }
+
+        [Test]
+        public void GetCapabilities_WithReference_ShouldReturnMatchingCapabilities()
+        {
+            var sharedApi = new TestSharedApi(
+                [TradingMode.Spot],
+                [TradingMode.Spot]);
+            var client = new TestSharedApiClient(sharedApi);
+
+            var result = client.GetCapabilities(
+                new SharedCapabilityReference<ITestCapability>(),
+                TradingMode.Spot);
+
+            Assert.That(result, Has.Count.EqualTo(1));
+            Assert.That(result[0].Capability, Is.SameAs(sharedApi));
+            Assert.That(result[0].Options, Is.SameAs(sharedApi.CapabilityOptions));
+        }
+
+        [Test]
+        public void Discover_ShouldReturnAllSharedApiInformation()
+        {
+            var restApi = new TestRestSharedApi();
+            var socketApi = new TestSocketSharedApi();
+            var client = new TestDiSharedApiClient(
+                restApi,
+                socketApi);
+
+            var result = client.Discover();
+
+            Assert.Multiple(() =>
+            {
+                Assert.That(result.PreferredTransport, Is.EqualTo(SharedTransport.Socket));
+                Assert.That(result.SharedApis, Has.Length.EqualTo(2));
+                Assert.That(result.SharedApis[0].Transport, Is.EqualTo(SharedTransport.Rest));
+                Assert.That(result.SharedApis[1].Transport, Is.EqualTo(SharedTransport.Socket));
+                Assert.That(result.SharedApis[0].SupportedTradingModes, Is.EqualTo(new[] { TradingMode.Spot }));
+                Assert.That(result.SharedApis[0].Capabilities, Has.Length.EqualTo(1));
+                Assert.That(result.SharedApis[0].Authenticated, Is.False);
+            });
+        }
+
+        [Test]
+        public void RegisterSharedApiClient_ShouldResolvePreferredTransport()
+        {
+            var restApi = new TestRestSharedApi();
+            var socketApi = new TestSocketSharedApi();
+            var services = new ServiceCollection();
+
+            services.AddSingleton(restApi);
+            services.AddSingleton(socketApi);
+
+            services.RegisterSharedApiClient<
+                ITestSharedApiClient,
+                TestDiSharedApiClient>(sharedApis => sharedApis
+                    .Add(client => client.Rest)
+                    .Add(client => client.Socket));
+
+            using var provider = services.BuildServiceProvider();
+
+            Assert.Multiple(() =>
+            {
+                Assert.That(
+                    provider.GetRequiredService<ITestSharedApiClient>(),
+                    Is.Not.Null);
+
+                Assert.That(
+                    provider.GetRequiredService<ISharedApiClientBase>(),
+                    Is.InstanceOf<TestDiSharedApiClient>());
+
+                Assert.That(
+                    provider.GetRequiredService<ITestCapability>(),
+                    Is.SameAs(socketApi));
+
+                Assert.That(
+                    provider.GetServices<ITestCapability>().ToArray(),
+                    Is.EqualTo(new[] { socketApi }));
+
+                Assert.That(
+                    provider.GetRequiredService<ITestRestCapability>(),
+                    Is.SameAs(restApi));
+
+                Assert.That(
+                    provider.GetRequiredService<ITestSocketCapability>(),
+                    Is.SameAs(socketApi));
+            });
+        }
+
+        [Test]
+        public void CapabilityTradingModes_ShouldIntersectApiApplicableAndOverrideModes()
+        {
+            var sharedApi = new TestSharedApi(
+                [TradingMode.Spot, TradingMode.PerpetualLinear, TradingMode.DeliveryLinear],
+                [TradingMode.Spot, TradingMode.PerpetualLinear],
+                [TradingMode.PerpetualLinear, TradingMode.DeliveryLinear]);
+
+            Assert.That(
+                sharedApi.CapabilityOptions.SupportedTradingModes,
+                Is.EqualTo(new[] { TradingMode.PerpetualLinear }));
+        }
+
+        [Test]
+        public void CapabilityOptions_ShouldApplyIntrinsicTradingModes()
+        {
+            var apiModes = new[]
+            {
+                TradingMode.Spot,
+                TradingMode.PerpetualLinear,
+                TradingMode.DeliveryLinear,
+                TradingMode.PerpetualInverse,
+                TradingMode.DeliveryInverse
+            };
+            var spotOptions = new PlaceSpotOrderOptions("TestExchange");
+            var futuresOptions = new GetPositionsOptions("TestExchange", false);
+            var perpetualOptions = new GetFundingRateHistoryOptions(
+                "TestExchange",
+                true,
+                true,
+                true,
+                100,
+                false);
+            var unrestrictedOptions = new GetTickerOptions("TestExchange");
+
+            _ = new TestOptionsHost(apiModes, spotOptions);
+            _ = new TestOptionsHost(apiModes, futuresOptions);
+            _ = new TestOptionsHost(apiModes, perpetualOptions);
+            _ = new TestOptionsHost(apiModes, unrestrictedOptions);
+
+            Assert.Multiple(() =>
+            {
+                Assert.That(spotOptions.SupportedTradingModes, Is.EqualTo(new[] { TradingMode.Spot }));
+                Assert.That(futuresOptions.SupportedTradingModes, Is.EqualTo(new[]
+                {
+                    TradingMode.PerpetualLinear,
+                    TradingMode.DeliveryLinear,
+                    TradingMode.PerpetualInverse,
+                    TradingMode.DeliveryInverse
+                }));
+                Assert.That(perpetualOptions.SupportedTradingModes, Is.EqualTo(new[]
+                {
+                    TradingMode.PerpetualLinear,
+                    TradingMode.PerpetualInverse
+                }));
+                Assert.That(unrestrictedOptions.SupportedTradingModes, Is.EqualTo(apiModes));
+            });
+        }
+
+        private interface ITestCapability : ISharedApiCapability
+        {
+        }
+
+        private sealed class TestApiClient : IBaseApiClient
+        {
+            public string Exchange => "TestExchange";
+            public string BaseAddress => "https://test.invalid";
+
+            public string FormatSymbol(
+                string baseAsset,
+                string quoteAsset,
+                TradingMode tradingMode,
+                DateTime? deliverDate = null)
+                => $"{baseAsset}{quoteAsset}";
+
+            public Task<TResult> WithRateLimitAdmissionAsync<TResult>(
+                RateLimitAdmission admission,
+                Func<Task<TResult>> operation)
+                => operation();
+        }
+
+        private interface ITestRestCapability : ITestCapability, ISharedRest
+        {
+        }
+
+        private interface ITestSocketCapability : ITestCapability, ISharedSocket
+        {
+        }
+
+        private interface ITestRestSharedApi : ITestRestCapability
+        {
+        }
+
+        private interface ITestSocketSharedApi : ITestSocketCapability
+        {
+        }
+
+        private interface ITestSharedApiClient : ISharedApiClientBase
+        {
+            ITestRestSharedApi Rest { get; }
+            ITestSocketSharedApi Socket { get; }
+        }
+
+        private sealed class TestCapabilityOptions : CapabilityOptions<SharedRequest, ITestCapability>
+        {
+            public override string Description => "Test capability";
+
+            public TestCapabilityOptions(TradingMode[]? applicableTradingModes)
+                : base("TestExchange", false, "TestOperation", [], applicableTradingModes)
+            {
+            }
+        }
+
+        private sealed class TestSharedApi : SharedApiBase, ITestCapability
+        {
+            public TestCapabilityOptions CapabilityOptions { get; }
+
+            public TestSharedApi(TradingMode[] apiTradingModes, TradingMode[]? capabilityTradingModes)
+                : this(apiTradingModes, capabilityTradingModes, null)
+            {
+            }
+
+            public TestSharedApi(
+                TradingMode[] apiTradingModes,
+                TradingMode[]? capabilityTradingModes,
+                TradingMode[]? applicableTradingModes)
+                : base(
+                    SharedTransport.Rest,
+                    new TestApiClient(),
+                    apiTradingModes,
+                    () => false,
+                    (baseAsset, quoteAsset, tradingMode, deliverDate) => $"{baseAsset}{quoteAsset}")
+            {
+                var options = new TestCapabilityOptions(applicableTradingModes)
+                {
+                    SupportedTradingModeOverrides = capabilityTradingModes
+                };
+
+                SetCapabilities(options);
+                CapabilityOptions = options;
+            }
+
+            public override SharedClientInfo Discover() => new();
+        }
+
+        private sealed class TestOptionsHost : SharedApiBase
+        {
+            public TestOptionsHost(TradingMode[] apiTradingModes, CapabilityOptions capabilityOptions)
+                : base(
+                    SharedTransport.Rest,
+                    new TestApiClient(),
+                    apiTradingModes,
+                    () => false,
+                    (baseAsset, quoteAsset, tradingMode, deliverDate) => $"{baseAsset}{quoteAsset}")
+            {
+                SetCapabilities(capabilityOptions);
+            }
+
+            public override SharedClientInfo Discover() => new();
+        }
+
+        private abstract class TestTransportSharedApi : SharedApiBase
+        {
+            protected TestTransportSharedApi(SharedTransport transport)
+                : base(
+                    transport,
+                    new TestApiClient(),
+                    [TradingMode.Spot],
+                    () => false,
+                    (baseAsset, quoteAsset, tradingMode, deliverDate) => $"{baseAsset}{quoteAsset}")
+            {
+                SetCapabilities(new TestCapabilityOptions([TradingMode.Spot]));
+            }
+
+            public override SharedClientInfo Discover() => new()
+            {
+                Exchange = this.Exchange,
+                TypeName = GetType().Name,
+                SupportedTradingModes = this.SupportedTradingModes,
+                Transport = this.Transport,
+                Authenticated = this.Authenticated,
+                Capabilities = ((ISharedApi)this).Capabilities.ToArray()
+            };
+        }
+
+        private sealed class TestRestSharedApi : TestTransportSharedApi, ITestRestSharedApi
+        {
+            public TestRestSharedApi() : base(SharedTransport.Rest)
+            {
+            }
+        }
+
+        private sealed class TestSocketSharedApi : TestTransportSharedApi, ITestSocketSharedApi
+        {
+            public TestSocketSharedApi() : base(SharedTransport.Socket)
+            {
+            }
+        }
+
+        private sealed class TestDiSharedApiClient : SharedApiClientBase, ITestSharedApiClient
+        {
+            public ITestRestSharedApi Rest { get; }
+            public ITestSocketSharedApi Socket { get; }
+
+            public TestDiSharedApiClient(
+                TestRestSharedApi rest,
+                TestSocketSharedApi socket)
+                : base(SharedTransport.Socket, rest, socket)
+            {
+                Rest = rest;
+                Socket = socket;
+            }
+        }
+
+        private sealed class TestSharedApiClient : SharedApiClientBase
+        {
+            public TestSharedApiClient(params ISharedApiCapability[] sharedApis)
+                : base(SharedTransport.Rest, sharedApis)
+            {
+            }
+        }
+    }
+}

CryptoExchange.Net.UnitTests/SharedCapabilitiesTests.cs

@@ -0,0 +1,89 @@
+using CryptoExchange.Net.SharedApis;
+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+
+namespace CryptoExchange.Net.UnitTests
+{
+    [TestFixture]
+    internal class SharedCapabilitiesTests
+    {
+        [Test]
+        public void AllSharedApiCapabilities_ShouldBeListedInSharedCapabilities()
+        {
+            var markerTypes = new[]
+            {
+                typeof(ISharedApiCapability),
+                typeof(ISharedRest),
+                typeof(ISharedSocket),
+                typeof(ISharedSubscription)
+            };
+
+            var expectedCapabilities = typeof(ISharedApiCapability).Assembly
+                .GetTypes()
+                .Where(x => x.IsInterface
+                            && typeof(ISharedApiCapability).IsAssignableFrom(x)
+                            && !markerTypes.Contains(x))
+                .OrderBy(x => x.FullName)
+                .ToArray();
+
+            var listedCapabilities = GetTypeAndNestedTypes(typeof(SharedCapabilities))
+                .SelectMany(x => x.GetProperties(
+                    BindingFlags.Public | BindingFlags.Static | BindingFlags.DeclaredOnly))
+                .SelectMany(x => x.PropertyType.GetGenericArguments())
+                .Where(x => x.IsInterface
+                            && typeof(ISharedApiCapability).IsAssignableFrom(x))
+                .ToArray();
+
+            var missingCapabilities = expectedCapabilities
+                .Except(listedCapabilities)
+                .Select(x => x.Name)
+                .ToArray();
+
+            var unknownCapabilities = listedCapabilities
+                .Except(expectedCapabilities)
+                .Select(x => x.Name)
+                .ToArray();
+
+            var duplicateCapabilities = listedCapabilities
+                .GroupBy(x => x)
+                .Where(x => x.Count() > 1)
+                .Select(x => x.Key.Name)
+                .ToArray();
+
+            Assert.Multiple(() =>
+            {
+                Assert.That(
+                    missingCapabilities,
+                    Is.Empty,
+                    $"Capabilities missing from SharedCapabilities: " +
+                    string.Join(", ", missingCapabilities));
+
+                Assert.That(
+                    unknownCapabilities,
+                    Is.Empty,
+                    $"Unknown capabilities listed in SharedCapabilities: " +
+                    string.Join(", ", unknownCapabilities));
+
+                Assert.That(
+                    duplicateCapabilities,
+                    Is.Empty,
+                    $"Capabilities listed multiple times in SharedCapabilities: " +
+                    string.Join(", ", duplicateCapabilities));
+            });
+        }
+
+        private static IEnumerable<Type> GetTypeAndNestedTypes(Type type)
+        {
+            yield return type;
+
+            foreach (var nestedType in type.GetNestedTypes(BindingFlags.Public))
+            {
+                foreach (var result in GetTypeAndNestedTypes(nestedType))
+                    yield return result;
+            }
+        }
+    }
+}

CryptoExchange.Net.UnitTests/SharedParametersTests.cs

@@ -0,0 +1,180 @@
+using NUnit.Framework;
+using CryptoExchange.Net.SharedApis;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+
+namespace CryptoExchange.Net.UnitTests
+{
+    [TestFixture]
+    internal class SharedParametersTests
+    {
+        [Test]
+        public void AllSharedAPIOptions_ShouldListAllDefaultParametersInRequestParameterRules()
+        {
+            var failures = new List<string>();
+
+            var optionsTypes = typeof(CapabilityOptions).Assembly
+                .GetTypes()
+                .Where(x => x.IsClass
+                            && !x.IsAbstract
+                            && typeof(CapabilityOptions).IsAssignableFrom(x))
+                .OrderBy(x => x.FullName)
+                .ToArray();
+
+            foreach (var optionsType in optionsTypes)
+            {
+                var genericOptionsType = GetGenericOptionsType(optionsType);
+                if (genericOptionsType == null)
+                {
+                    if (optionsType == typeof(ClosePositionOptions))
+                        continue;
+
+                    failures.Add($"{optionsType.Name}: unable to determine request type");
+                    continue;
+                }
+
+                var requestType = genericOptionsType.GetGenericArguments()[0];
+                var defaultRulesField = GetDefaultParameterRulesField(optionsType);
+                if (defaultRulesField == null)
+                {
+                    failures.Add($"{optionsType.Name}: no _defaultParameterRules field found");
+                    continue;
+                }
+
+                var rules = (RequestParameterDescription[]?)defaultRulesField.GetValue(null);
+                if (rules == null)
+                {
+                    failures.Add($"{optionsType.Name}: _defaultParameterRules is null");
+                    continue;
+                }
+
+                var constructorParameterNames = requestType
+                    .GetConstructors(BindingFlags.Instance | BindingFlags.Public)
+                    .SelectMany(x => x.GetParameters())
+                    .Where(x => !string.Equals(
+                        x.Name,
+                        "exchangeParameters",
+                        StringComparison.OrdinalIgnoreCase))
+                    .Select(x => x.Name!)
+                    .ToHashSet(StringComparer.OrdinalIgnoreCase);
+
+                var parameterProperties = requestType
+                    .GetProperties(BindingFlags.Instance | BindingFlags.Public)
+                    .Where(x => x.DeclaringType == requestType
+                                || constructorParameterNames.Contains(x.Name))
+                    .Where(x => x.Name != nameof(SharedRequest.ExchangeParameters))
+                    .Select(x => x.Name)
+                    .OrderBy(x => x)
+                    .ToArray();
+
+                var ruleNames = rules
+                    .Select(x => x.Name)
+                    .ToHashSet(StringComparer.Ordinal);
+
+                foreach (var parameterProperty in parameterProperties)
+                {
+                    if (!ruleNames.Contains(parameterProperty))
+                    {
+                        failures.Add(
+                            $"{optionsType.Name}: request property " +
+                            $"{requestType.Name}.{parameterProperty} has no default request parameter rule");
+                    }
+                }
+            }
+
+            Assert.That(
+                failures,
+                Is.Empty,
+                $"Missing default request parameter rules:{Environment.NewLine}" +
+                string.Join(Environment.NewLine, failures));
+        }
+
+        [Test]
+        public void RequiredExchangeParameter_ShouldAcceptNameOrAnyAlias()
+        {
+            const string exchange = "TestExchange";
+            var options = new GetTickerOptions(exchange)
+            {
+                ExchangeParameterRules =
+                [
+                    ExchangeParameterRule.Required(
+                        "Parameter",
+                        "Test parameter",
+                        1,
+                        "Alias1",
+                        "Alias2")
+                ]
+            };
+
+            var missingResult = options.ValidateRequest(null, null, [TradingMode.Spot]);
+            var nameResult = options.ValidateRequest(
+                new ExchangeParameters(new ExchangeParameter(exchange, "Parameter", 1)),
+                null,
+                [TradingMode.Spot]);
+            var firstAliasResult = options.ValidateRequest(
+                new ExchangeParameters(new ExchangeParameter(exchange, "Alias1", 1)),
+                null,
+                [TradingMode.Spot]);
+            var secondAliasResult = options.ValidateRequest(
+                new ExchangeParameters(new ExchangeParameter(exchange, "Alias2", 1)),
+                null,
+                [TradingMode.Spot]);
+
+            Assert.Multiple(() =>
+            {
+                Assert.That(missingResult, Is.Not.Null);
+                Assert.That(nameResult, Is.Null);
+                Assert.That(firstAliasResult, Is.Null);
+                Assert.That(secondAliasResult, Is.Null);
+            });
+        }
+
+        [Test]
+        public void RequiredExchangeParameterWithoutAliases_ShouldBeRequired()
+        {
+            const string exchange = "TestExchange";
+            var options = new GetTickerOptions(exchange)
+            {
+                ExchangeParameterRules =
+                [
+                    ExchangeParameterRule.Required(
+                        "Parameter",
+                        "Test parameter",
+                        1)
+                ]
+            };
+
+            var result = options.ValidateRequest(null, null, [TradingMode.Spot]);
+
+            Assert.That(result, Is.Not.Null);
+        }
+
+        private static Type? GetGenericOptionsType(Type optionsType)
+        {
+            for (var type = optionsType; type != null; type = type.BaseType)
+            {
+                if (type.IsGenericType
+                    && type.GetGenericTypeDefinition() == typeof(CapabilityOptions<,>))
+                    return type;
+            }
+
+            return null;
+        }
+
+        private static FieldInfo? GetDefaultParameterRulesField(Type optionsType)
+        {
+            for (var type = optionsType; type != null; type = type.BaseType)
+            {
+                var field = type.GetField(
+                    "_defaultParameterRules",
+                    BindingFlags.Static | BindingFlags.NonPublic | BindingFlags.DeclaredOnly);
+                if (field != null)
+                    return field;
+            }
+
+            return null;
+        }
+    }
+}