Fix ExactMatcher and JsonMatcher not working for ISO dates as string

src/WireMock.Net.Extensions.Routing/WireMock.Net.Extensions.Routing.csproj

@@ -25,7 +25,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-      <PackageReference Include="JsonConverter.Abstractions" Version="0.8.0" />
+      <PackageReference Include="JsonConverter.Abstractions" Version="0.9.0" />
     </ItemGroup>
 
     <ItemGroup>

src/WireMock.Net.Minimal/Serialization/MappingSerializer.cs

@@ -1,6 +1,7 @@
 // Copyright © WireMock.Net
 
 using JsonConverter.Abstractions;
+using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
 #if NETSTANDARD2_0_OR_GREATER || NETCOREAPP3_1_OR_GREATER || NET6_0_OR_GREATER || NET461
 using System.Text.Json;
@@ -10,9 +11,15 @@ namespace WireMock.Serialization;
 
 internal class MappingSerializer(IJsonConverter jsonConverter)
 {
+    private static readonly JsonConverterOptions JsonConverterOptions = new JsonConverterOptions
+    {
+        DateParseHandling = (int) DateParseHandling.None
+    };
+
     internal T[] DeserializeJsonToArray<T>(string value)
     {
-        return DeserializeObjectToArray<T>(jsonConverter.Deserialize<object>(value)!);
+        // DeserializeObject
+        return DeserializeObjectToArray<T>(jsonConverter.Deserialize<object>(value, JsonConverterOptions)!);
     }
 
     internal static T[] DeserializeObjectToArray<T>(object value)

src/WireMock.Net.Minimal/Server/WireMockServer.Admin.cs

@@ -1,6 +1,5 @@
 // Copyright © WireMock.Net
 
-using System.Linq;
 using System.Net;
 using System.Text;
 using JetBrains.Annotations;
@@ -26,9 +25,6 @@
 
 namespace WireMock.Server;
 
-/// <summary>
-/// The fluent mock server.
-/// </summary>
 public partial class WireMockServer
 {
     private const int EnhancedFileSystemWatcherTimeoutMs = 1000;

src/WireMock.Net.NUnit/WireMock.Net.NUnit.csproj

@@ -25,7 +25,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="JsonConverter.Newtonsoft.Json" Version="0.8.0" />
+        <PackageReference Include="JsonConverter.Newtonsoft.Json" Version="0.9.0" />
         <PackageReference Include="NUnit" Version="4.4.0" />
         <PackageReference Include="Stef.Validation" Version="0.2.0" />
     </ItemGroup>

src/WireMock.Net.RestClient/WireMock.Net.RestClient.csproj

@@ -33,7 +33,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="JsonConverter.Newtonsoft.Json" Version="0.8.0" />
+        <PackageReference Include="JsonConverter.Newtonsoft.Json" Version="0.9.0" />
         <PackageReference Include="RestEase" Version="1.6.4" />
         <PackageReference Include="Stef.Validation" Version="0.2.0" />
     </ItemGroup>

src/WireMock.Net.Shared/WireMock.Net.Shared.csproj

@@ -30,7 +30,7 @@
         <PackageReference Include="Stef.Validation" Version="0.2.0" />
         <PackageReference Include="AnyOf" Version="0.5.0.1" />
         <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="8.0.2" />
-        <PackageReference Include="JsonConverter.Newtonsoft.Json" Version="0.8.0" />
+        <PackageReference Include="JsonConverter.Newtonsoft.Json" Version="0.9.0" />
     </ItemGroup>
 
     <ItemGroup>

test/WireMock.Net.Tests/Serialization/MappingSerializerTests.cs

@@ -3,6 +3,8 @@
 using JsonConverter.Newtonsoft.Json;
 using WireMock.Admin.Mappings;
 using WireMock.Serialization;
+using Newtonsoft.Json.Linq;
+
 #if NET8_0_OR_GREATER
 using JsonConverter.System.Text.Json;
 #endif
@@ -319,5 +321,92 @@ public void MappingSerializer_DeserializeJsonToArray_WithSystemTextJson_Primitiv
         act.Should().Throw<InvalidOperationException>()
             .WithMessage("Cannot deserialize the provided value to an array or object.");
     }
+
+    [Fact]
+    public void MappingSerializer_DeserializeJsonToArray_WithNewtonsoftJson_DateTimeStringInQueryParamExactMatcherPattern_ShouldPreservePatternAsString()
+    {
+        // Arrange
+        var jsonConverter = new NewtonsoftJsonConverter();
+        var serializer = new MappingSerializer(jsonConverter);
+        var mappingJson =
+            """
+            {
+                "Guid": "12345678-1234-1234-1234-aaaaaaaaaaaa",
+                "Request": {
+                    "Path": "/api/report",
+                    "Methods": ["GET"],
+                    "Params": [
+                        {
+                            "Name": "asOfDate",
+                            "Matchers": [
+                                {
+                                    "Name": "ExactMatcher",
+                                    "Pattern": "2021-11-10T13:39:13.705"
+                                }
+                            ]
+                        }
+                    ]
+                },
+                "Response": {
+                    "StatusCode": 200
+                }
+            }
+            """;
+
+        // Act
+        var result = serializer.DeserializeJsonToArray<MappingModel>(mappingJson);
+
+        // Assert
+        result.Should().HaveCount(1);
+        var matcher = result[0].Request!.Params![0].Matchers![0];
+        matcher.Name.Should().Be("ExactMatcher");
+        matcher.Pattern.Should().BeOfType<string>()
+            .Which.Should().Be("2021-11-10T13:39:13.705",
+                "datetime-format strings in ExactMatcher Pattern fields must survive deserialization as strings, " +
+                "not be auto-converted to DateTime by Newtonsoft.Json's DateParseHandling.DateTime");
+    }
+
+    [Fact]
+    public void MappingSerializer_DeserializeJsonToArray_WithNewtonsoftJson_DateTimeStringInJsonMatcherBodyPattern_ShouldPreservePatternAsString()
+    {
+        // Arrange
+        var jsonConverter = new NewtonsoftJsonConverter();
+        var serializer = new MappingSerializer(jsonConverter);
+        // Pattern is an INLINE JSON object (not a string) - this is how WireMock mapping files store
+        // JsonMatcher patterns when recorded. Newtonsoft with DateParseHandling.DateTime will convert
+        // the datetime value inside the JObject to JTokenType.Date during deserialization.
+        var mappingJson =
+            """
+            {
+                "Guid": "12345678-1234-1234-1234-bbbbbbbbbbbb",
+                "Request": {
+                    "Path": "/api/report",
+                    "Methods": ["POST"],
+                    "Body": {
+                        "Matcher": {
+                            "Name": "JsonMatcher",
+                            "Pattern": {"Date": "2021-09-30T00:00:00Z", "Names": ["Cash"]}
+                        }
+                    }
+                },
+                "Response": {
+                    "StatusCode": 200
+                }
+            }
+            """;
+
+        // Act
+        var result = serializer.DeserializeJsonToArray<MappingModel>(mappingJson);
+
+        // Assert - datetime values inside the JObject pattern must remain JTokenType.String.
+        result.Should().HaveCount(1);
+        var matcher = result[0].Request!.Body!.Matcher!;
+        matcher.Name.Should().Be("JsonMatcher");
+        var patternJObject = matcher.Pattern.Should().BeOfType<JObject>().Subject;
+        patternJObject["Date"]!.Type.Should().Be(JTokenType.String,
+            "datetime-format strings inside an inline JsonMatcher body pattern must retain JTokenType.String " +
+            "after deserialization; if DateParseHandling.DateTime auto-converts them to JTokenType.Date, " +
+            "JToken.DeepEquals will fail against incoming request bodies parsed with DateParseHandling.None");
+    }
 #endif
 }