[FSSDK-11150] cmab client implementation

OptimizelySDK.NetStandard20/OptimizelySDK.NetStandard20.csproj

@@ -181,6 +181,21 @@
     <Compile Include="..\OptimizelySDK\Entity\Cmab.cs">
       <Link>Entity\Cmab.cs</Link>
     </Compile>
+    <Compile Include="..\OptimizelySDK\Cmab\ICmabClient.cs">
+      <Link>Cmab\ICmabClient.cs</Link>
+    </Compile>
+    <Compile Include="..\OptimizelySDK\Cmab\DefaultCmabClient.cs">
+      <Link>Cmab\DefaultCmabClient.cs</Link>
+    </Compile>
+    <Compile Include="..\OptimizelySDK\Cmab\CmabRetryConfig.cs">
+      <Link>Cmab\CmabRetryConfig.cs</Link>
+    </Compile>
+    <Compile Include="..\OptimizelySDK\Cmab\CmabModels.cs">
+      <Link>Cmab\CmabModels.cs</Link>
+    </Compile>
+    <Compile Include="..\OptimizelySDK\Cmab\CmabConstants.cs">
+      <Link>Cmab\CmabConstants.cs</Link>
+    </Compile>
     <Compile Include="..\OptimizelySDK\Entity\Holdout.cs">
       <Link>Entity\Holdout.cs</Link>
     </Compile>

OptimizelySDK.Tests/CmabTests/DefaultCmabClientTest.cs

@@ -0,0 +1,186 @@
+/* 
+* Copyright 2025, Optimizely
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+using System;
+using System.Collections.Generic;
+using System.Net;
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+using Moq;
+using Moq.Protected;
+using NUnit.Framework;
+using OptimizelySDK.Cmab;
+using OptimizelySDK.ErrorHandler;
+using OptimizelySDK.Exceptions;
+using OptimizelySDK.Logger;
+
+namespace OptimizelySDK.Tests.CmabTests
+{
+    [TestFixture]
+    public class DefaultCmabClientTest
+    {
+        private class ResponseStep
+        {
+            public HttpStatusCode Status { get; private set; }
+            public string Body { get; private set; }
+            public ResponseStep(HttpStatusCode status, string body)
+            {
+                Status = status;
+                Body = body;
+            }
+        }
+
+        private static HttpClient MakeClient(params ResponseStep[] sequence)
+        {
+            var handler = new Mock<HttpMessageHandler>(MockBehavior.Strict);
+            var queue = new Queue<ResponseStep>(sequence);
+
+            handler.Protected().Setup<Task<HttpResponseMessage>>("SendAsync",
+                ItExpr.IsAny<HttpRequestMessage>(),
+                ItExpr.IsAny<CancellationToken>()).Returns((HttpRequestMessage _, CancellationToken __) =>
+            {
+                if (queue.Count == 0)
+                    throw new InvalidOperationException("No more mocked responses available.");
+
+                var step = queue.Dequeue();
+                var response = new HttpResponseMessage(step.Status);
+                if (step.Body != null)
+                {
+                    response.Content = new StringContent(step.Body);
+                }
+                return Task.FromResult(response);
+            });
+
+            return new HttpClient(handler.Object);
+        }
+
+        private static HttpClient MakeClientExceptionSequence(params Exception[] sequence)
+        {
+            var handler = new Mock<HttpMessageHandler>(MockBehavior.Strict);
+            var queue = new Queue<Exception>(sequence);
+
+            handler.Protected().Setup<Task<HttpResponseMessage>>("SendAsync",
+                ItExpr.IsAny<HttpRequestMessage>(),
+                ItExpr.IsAny<CancellationToken>()).Returns((HttpRequestMessage _, CancellationToken __) =>
+            {
+                if (queue.Count == 0)
+                    throw new InvalidOperationException("No more mocked exceptions available.");
+
+                var ex = queue.Dequeue();
+                var tcs = new TaskCompletionSource<HttpResponseMessage>();
+                tcs.SetException(ex);
+                return tcs.Task;
+            });
+
+            return new HttpClient(handler.Object);
+        }
+
+        private static string ValidBody(string variationId = "v1")
+            => $"{{\"predictions\":[{{\"variation_id\":\"{variationId}\"}}]}}";
+
+        [Test]
+        public void FetchDecisionReturnsSuccessNoRetry()
+        {
+            var http = MakeClient(new ResponseStep(HttpStatusCode.OK, ValidBody("v1")));
+            var client = new DefaultCmabClient(http, retryConfig: null, logger: new NoOpLogger(), errorHandler: new NoOpErrorHandler());
+            var result = client.FetchDecision("rule-1", "user-1", null, "uuid-1");
+
+            Assert.AreEqual("v1", result);
+        }
+
+        [Test]
+        public void FetchDecisionHttpExceptionNoRetry()
+        {
+            var http = MakeClientExceptionSequence(new HttpRequestException("boom"));
+            var client = new DefaultCmabClient(http, retryConfig: null);
+
+            Assert.Throws<CmabFetchException>(() =>
+                client.FetchDecision("rule-1", "user-1", null, "uuid-1"));
+        }
+
+        [Test]
+        public void FetchDecisionNon2xxNoRetry()
+        {
+            var http = MakeClient(new ResponseStep(HttpStatusCode.InternalServerError, null));
+            var client = new DefaultCmabClient(http, retryConfig: null);
+
+            Assert.Throws<CmabFetchException>(() =>
+                client.FetchDecision("rule-1", "user-1", null, "uuid-1"));
+        }
+
+        [Test]
+        public void FetchDecisionInvalidJsonNoRetry()
+        {
+            var http = MakeClient(new ResponseStep(HttpStatusCode.OK, "not json"));
+            var client = new DefaultCmabClient(http, retryConfig: null);
+
+            Assert.Throws<CmabInvalidResponseException>(() =>
+                client.FetchDecision("rule-1", "user-1", null, "uuid-1"));
+        }
+
+        [Test]
+        public void FetchDecisionInvalidStructureNoRetry()
+        {
+            var http = MakeClient(new ResponseStep(HttpStatusCode.OK, "{\"predictions\":[]}"));
+            var client = new DefaultCmabClient(http, retryConfig: null);
+
+            Assert.Throws<CmabInvalidResponseException>(() =>
+                client.FetchDecision("rule-1", "user-1", null, "uuid-1"));
+        }
+
+        [Test]
+        public void FetchDecisionSuccessWithRetryFirstTry()
+        {
+            var http = MakeClient(new ResponseStep(HttpStatusCode.OK, ValidBody("v2")));
+            var retry = new CmabRetryConfig(maxRetries: 2, initialBackoff: TimeSpan.Zero, maxBackoff: TimeSpan.FromSeconds(1), backoffMultiplier: 2.0);
+            var client = new DefaultCmabClient(http, retry);
+            var result = client.FetchDecision("rule-1", "user-1", null, "uuid-1");
+
+            Assert.AreEqual("v2", result);
+        }
+
+        [Test]
+        public void FetchDecisionSuccessWithRetryThirdTry()
+        {
+            var http = MakeClient(
+                new ResponseStep(HttpStatusCode.InternalServerError, null),
+                new ResponseStep(HttpStatusCode.InternalServerError, null),
+                new ResponseStep(HttpStatusCode.OK, ValidBody("v3"))
+            );
+            var retry = new CmabRetryConfig(maxRetries: 2, initialBackoff: TimeSpan.Zero, maxBackoff: TimeSpan.FromSeconds(1), backoffMultiplier: 2.0);
+            var client = new DefaultCmabClient(http, retry);
+            var result = client.FetchDecision("rule-1", "user-1", null, "uuid-1");
+
+            Assert.AreEqual("v3", result);
+        }
+
+        [Test]
+        public void FetchDecisionExhaustsAllRetries()
+        {
+            var http = MakeClient(
+                new ResponseStep(HttpStatusCode.InternalServerError, null),
+                new ResponseStep(HttpStatusCode.InternalServerError, null),
+                new ResponseStep(HttpStatusCode.InternalServerError, null)
+            );
+            var retry = new CmabRetryConfig(maxRetries: 2, initialBackoff: TimeSpan.Zero, maxBackoff: TimeSpan.FromSeconds(1), backoffMultiplier: 2.0);
+            var client = new DefaultCmabClient(http, retry);
+
+            Assert.Throws<CmabFetchException>(() =>
+                client.FetchDecision("rule-1", "user-1", null, "uuid-1"));
+        }
+    }
+}

OptimizelySDK.Tests/OptimizelySDK.Tests.csproj

@@ -70,6 +70,7 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="Assertions.cs"/>
+    <Compile Include="CmabTests\DefaultCmabClientTest.cs"/>
     <Compile Include="AudienceConditionsTests\ConditionEvaluationTest.cs"/>
     <Compile Include="AudienceConditionsTests\ConditionsTest.cs"/>
     <Compile Include="AudienceConditionsTests\SegmentsTests.cs"/>

OptimizelySDK/Cmab/CmabConstants.cs

@@ -0,0 +1,32 @@
+/* 
+* Copyright 2025, Optimizely
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+using System;
+
+namespace OptimizelySDK.Cmab
+{
+    internal static class CmabConstants
+    {
+        public const string PredictionUrl = "https://prediction.cmab.optimizely.com/predict";
+        public static readonly TimeSpan MaxTimeout = TimeSpan.FromSeconds(10);
+
+        public const string ContentTypeJson = "application/json";
+
+        public const string ErrorFetchFailedFmt = "CMAB decision fetch failed with status: {0}";
+        public const string ErrorInvalidResponse = "Invalid CMAB fetch response";
+        public const string ExhaustRetryMessage = "Exhausted all retries for CMAB request";
+    }
+}

OptimizelySDK/Cmab/CmabModels.cs

@@ -0,0 +1,41 @@
+/* 
+* Copyright 2025, Optimizely
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+using System.Collections.Generic;
+using Newtonsoft.Json;
+
+namespace OptimizelySDK.Cmab
+{
+    internal class CmabAttribute
+    {
+        [JsonProperty("id")] public string Id { get; set; }
+        [JsonProperty("value")] public object Value { get; set; }
+        [JsonProperty("type")] public string Type { get; set; } = "custom_attribute";
+    }
+
+    internal class CmabInstance
+    {
+        [JsonProperty("visitorId")] public string VisitorId { get; set; }
+        [JsonProperty("experimentId")] public string ExperimentId { get; set; }
+        [JsonProperty("attributes")] public List<CmabAttribute> Attributes { get; set; }
+        [JsonProperty("cmabUUID")] public string CmabUUID { get; set; }
+    }
+
+    internal class CmabRequest
+    {
+        [JsonProperty("instances")] public List<CmabInstance> Instances { get; set; }
+    }
+}

OptimizelySDK/Cmab/CmabRetryConfig.cs

@@ -0,0 +1,43 @@
+/* 
+* Copyright 2025, Optimizely
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+using System;
+
+namespace OptimizelySDK.Cmab
+{
+    /// <summary>
+    /// Configuration for retrying CMAB requests (exponential backoff).
+    /// </summary>
+    public class CmabRetryConfig
+    {
+        public int MaxRetries { get; }
+        public TimeSpan InitialBackoff { get; }
+        public TimeSpan MaxBackoff { get; }
+        public double BackoffMultiplier { get; }
+
+        public CmabRetryConfig(
+            int maxRetries = 3,
+            TimeSpan? initialBackoff = null,
+            TimeSpan? maxBackoff = null,
+            double backoffMultiplier = 2.0)
+        {
+            MaxRetries = maxRetries;
+            InitialBackoff = initialBackoff ?? TimeSpan.FromMilliseconds(100);
+            MaxBackoff = maxBackoff ?? TimeSpan.FromSeconds(10);
+            BackoffMultiplier = backoffMultiplier;
+        }
+    }
+}