Minor improvements and fixes

appveyor.yml

@@ -1,5 +1,5 @@
 environment:
-  build_version: 9.0.0
+  build_version: 9.0.1
 version: $(build_version)-{build}
 image: Visual Studio 2022
 configuration: Release

src/ConfigCat.Client.Tests/ConfigV1EvaluationTests.cs

@@ -55,7 +55,7 @@ public class SensitiveTestsDescriptor : IMatrixTestDescriptor
         public static IEnumerable<object?[]> GetTests() => MatrixTestRunner<SensitiveTestsDescriptor>.GetTests();
     }
 
-    public class VariationIdTestsDescriptor : IMatrixTestDescriptor, IVariationIdMatrixText
+    public class VariationIdTestsDescriptor : IMatrixTestDescriptor, IVariationIdMatrixTest
     {
         // https://app.configcat.com/08d5a03c-feb7-af1e-a1fa-40b3329f8bed/08d774b9-3d05-0027-d5f4-3e76c3dba752/244cf8b0-f604-11e8-b543-f23c917f9d8d
         public ConfigLocation ConfigLocation => new ConfigLocation.Cdn("PKDVCLf-Hq-h-kCzMp-L7Q/nQ5qkhRAUEa6beEyyrVLBA");

src/ConfigCat.Client.Tests/ConfigV2EvaluationTests.cs

@@ -64,7 +64,7 @@ public class SensitiveTestsDescriptor : IMatrixTestDescriptor
         public static IEnumerable<object?[]> GetTests() => MatrixTestRunner<SensitiveTestsDescriptor>.GetTests();
     }
 
-    public class VariationIdTestsDescriptor : IMatrixTestDescriptor, IVariationIdMatrixText
+    public class VariationIdTestsDescriptor : IMatrixTestDescriptor, IVariationIdMatrixTest
     {
         //https://app.configcat.com/v2/e7a75611-4256-49a5-9320-ce158755e3ba/08d5a03c-feb7-af1e-a1fa-40b3329f8bed/08dbc4dc-30c6-4969-8e4c-03f6a8764199/244cf8b0-f604-11e8-b543-f23c917f9d8d
         public ConfigLocation ConfigLocation => new ConfigLocation.Cdn("configcat-sdk-1/PKDVCLf-Hq-h-kCzMp-L7Q/spQnkRTIPEWVivZkWM84lQ");

src/ConfigCat.Client.Tests/MatrixTestRunnerBase.cs

@@ -23,7 +23,7 @@ public interface IMatrixTestDescriptor
     public string MatrixResultFileName { get; }
 }
 
-public interface IVariationIdMatrixText { }
+public interface IVariationIdMatrixTest { }
 
 public class MatrixTestRunnerBase<TDescriptor> where TDescriptor : IMatrixTestDescriptor, new()
 {
@@ -34,7 +34,7 @@ public interface IVariationIdMatrixText { }
 
     public MatrixTestRunnerBase()
     {
-        this.isVariationIdMatrixTest = DescriptorInstance is IVariationIdMatrixText;
+        this.isVariationIdMatrixTest = DescriptorInstance is IVariationIdMatrixTest;
         this.config = DescriptorInstance.ConfigLocation.FetchConfigCached().Settings;
     }
 

src/ConfigCatClient/HttpConfigFetcher.cs

@@ -5,12 +5,6 @@
 using System.Threading;
 using System.Threading.Tasks;
 
-#if NET45
-using ResponseWithBody = System.Tuple<System.Net.Http.HttpResponseMessage, string?, ConfigCat.Client.Config?>;
-#else
-using ResponseWithBody = System.ValueTuple<System.Net.Http.HttpResponseMessage, string?, ConfigCat.Client.Config?>;
-#endif
-
 namespace ConfigCat.Client;
 
 internal sealed class HttpConfigFetcher : IConfigFetcher, IDisposable
@@ -85,22 +79,24 @@ private async ValueTask<FetchResult> FetchInternalAsync(ProjectConfig lastConfig
         {
             var responseWithBody = await FetchRequestAsync(lastConfig.HttpETag, this.requestUri).ConfigureAwait(false);
 
-            var response = responseWithBody.Item1;
+            var response = responseWithBody.Response;
 
             switch (response.StatusCode)
             {
                 case HttpStatusCode.OK:
-                    if (responseWithBody.Item2 is null)
+                    var config = responseWithBody.Config;
+                    if (config is null)
                     {
-                        logMessage = this.logger.FetchReceived200WithInvalidBody();
-                        return FetchResult.Failure(lastConfig, logMessage.InvariantFormattedMessage);
+                        var exception = responseWithBody.Exception;
+                        logMessage = this.logger.FetchReceived200WithInvalidBody(exception);
+                        return FetchResult.Failure(lastConfig, logMessage.InvariantFormattedMessage, exception);
                     }
 
                     return FetchResult.Success(new ProjectConfig
                     (
                         httpETag: response.Headers.ETag?.Tag,
-                        configJson: responseWithBody.Item2,
-                        config: responseWithBody.Item3,
+                        configJson: responseWithBody.ResponseBody,
+                        config: config,
                         timeStamp: ProjectConfig.GenerateTimeStamp()
                     ));
 
@@ -177,11 +173,9 @@ private async ValueTask<ResponseWithBody> FetchRequestAsync(string? httpETag, Ur
                 var responseBody = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
 #endif
 
-                var config = responseBody.DeserializeOrDefault<Config>();
-                if (config is null)
-                {
-                    return new ResponseWithBody(response, null, null);
-                }
+                Config config;
+                try { config = Config.Deserialize(responseBody.AsMemory()); }
+                catch (Exception ex) { return new ResponseWithBody(response, responseBody, ex); }
 
                 if (config.Preferences is not null)
                 {
@@ -224,7 +218,7 @@ private async ValueTask<ResponseWithBody> FetchRequestAsync(string? httpETag, Ur
                 return new ResponseWithBody(response, responseBody, config);
             }
 
-            return new ResponseWithBody(response, null, null);
+            return new ResponseWithBody(response, null, (Exception?)null);
         }
     }
 
@@ -277,4 +271,28 @@ public void Dispose()
         this.cancellationTokenSource.Cancel();
         this.httpClient?.Dispose();
     }
+
+    private readonly struct ResponseWithBody
+    {
+        private readonly object? configOrException;
+
+        public ResponseWithBody(HttpResponseMessage response, string responseBody, Config config)
+        {
+            Response = response;
+            ResponseBody = responseBody;
+            this.configOrException = config;
+        }
+
+        public ResponseWithBody(HttpResponseMessage response, string? responseBody, Exception? exception)
+        {
+            Response = response;
+            ResponseBody = responseBody;
+            this.configOrException = exception;
+        }
+
+        public HttpResponseMessage Response { get; }
+        public string? ResponseBody { get; }
+        public Config? Config => this.configOrException as Config;
+        public Exception? Exception => this.configOrException as Exception;
+    }
 }

src/ConfigCatClient/Logging/LogMessages.cs

@@ -53,14 +53,14 @@ public static FormattableLogMessage FetchFailedDueToRequestTimeout(this LoggerWr
 
     public static FormattableLogMessage FetchFailedDueToUnexpectedError(this LoggerWrapper logger, Exception ex) => logger.Log(
         LogLevel.Error, 1103, ex,
-        "Unexpected error occurred while trying to fetch config JSON.");
+        "Unexpected error occurred while trying to fetch config JSON. It is most likely due to a local network issue. Please make sure your application can reach the ConfigCat CDN servers (or your proxy server) over HTTP.");
 
     public static FormattableLogMessage FetchFailedDueToRedirectLoop(this LoggerWrapper logger) => logger.Log(
         LogLevel.Error, 1104,
         "Redirection loop encountered while trying to fetch config JSON. Please contact us at https://configcat.com/support/");
 
-    public static FormattableLogMessage FetchReceived200WithInvalidBody(this LoggerWrapper logger) => logger.Log(
-        LogLevel.Error, 1105,
+    public static FormattableLogMessage FetchReceived200WithInvalidBody(this LoggerWrapper logger, Exception? ex) => logger.Log(
+        LogLevel.Error, 1105, ex,
         "Fetching config JSON was successful but the HTTP response content was invalid.");
 
     public static FormattableLogMessage FetchReceived304WhenLocalCacheIsEmpty(this LoggerWrapper logger, int statusCode, string? reasonPhrase) => logger.LogInterpolated(

src/ConfigCatClient/Models/Config.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Diagnostics.CodeAnalysis;
@@ -39,6 +40,12 @@ internal sealed class Config : IConfig
     , IJsonOnDeserialized
 #endif
 {
+    public static Config Deserialize(ReadOnlyMemory<char> configJson, bool tolerant = false)
+    {
+        return configJson.Deserialize<Config>(tolerant)
+            ?? throw new ArgumentException("Invalid config JSON content: " + configJson, nameof(configJson));
+    }
+
 #if USE_NEWTONSOFT_JSON
     [JsonProperty(PropertyName = "p")]
 #else

src/ConfigCatClient/Models/SegmentComparator.cs

@@ -8,10 +8,10 @@ public enum SegmentComparator : byte
     /// <summary>
     /// IS IN SEGMENT - It matches when the conditions of the specified segment are evaluated to true.
     /// </summary>
-    IsIn,
+    IsIn = 0,
 
     /// <summary>
     /// IS NOT IN SEGMENT - It matches when the conditions of the specified segment are evaluated to false.
     /// </summary>
-    IsNotIn,
+    IsNotIn = 1,
 }

src/ConfigCatClient/Override/LocalFileDataSource.cs

@@ -111,8 +111,7 @@ private async Task ReloadFileAsync(bool isAsync, CancellationToken cancellationT
                         break;
                     }
 
-                    var deserialized = content.Deserialize<Config>(tolerant: true)
-                        ?? throw new InvalidOperationException("Invalid config JSON content: " + content);
+                    var deserialized = Config.Deserialize(content.AsMemory(), tolerant: true);
                     this.overrideValues = deserialized.Settings;
                     break;
                 }

src/ConfigCatClient/ProjectConfig.cs

@@ -87,11 +87,7 @@ public static ProjectConfig Deserialize(string value)
         string? configJson;
         if (configJsonSpan.Length > 0)
         {
-            config = configJsonSpan.DeserializeOrDefault<Config>();
-            if (config is null)
-            {
-                throw new FormatException("Invalid config JSON content: " + configJsonSpan.ToString());
-            }
+            config = Config.Deserialize(configJsonSpan);
             configJson = configJsonSpan.ToString();
         }
         else