diff --git a/test/Protobuf.System.Text.Json.Tests/ContractEvolutionTests.cs b/test/Protobuf.System.Text.Json.Tests/ContractEvolutionTests.cs
index ef47041..163b963 100644
--- a/test/Protobuf.System.Text.Json.Tests/ContractEvolutionTests.cs
+++ b/test/Protobuf.System.Text.Json.Tests/ContractEvolutionTests.cs
@@ -1,7 +1,6 @@
 using System.Text.Json;
 using System.Text.Json.Protobuf.Tests;
 using Protobuf.System.Text.Json.Tests.Utils;
-using Shouldly;
 using Xunit;
 
 namespace Protobuf.System.Text.Json.Tests;
@@ -25,8 +24,8 @@ public void Should_deserialize_a_new_version_of_a_message_using_the_old_version_
         var deserialized = JsonSerializer.Deserialize<MessageWithVersionMismatch>(payload, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.DoubleProperty.ShouldBe(msg.DoubleProperty);
+        Assert.NotNull(deserialized);
+        Assert.Equal(msg.DoubleProperty, deserialized.DoubleProperty);
     }
     
     [Fact]
@@ -44,7 +43,7 @@ public void Should_deserialize_the_old_version_of_a_message_using_the_new_versio
         var deserialized = JsonSerializer.Deserialize<MessageWithVersionMismatchV2>(payload, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.DoubleProperty.ShouldBe(msg.DoubleProperty);
+        Assert.NotNull(deserialized);
+        Assert.Equal(msg.DoubleProperty, deserialized.DoubleProperty);
     }
 }
\ No newline at end of file
diff --git a/test/Protobuf.System.Text.Json.Tests/MessageWithComplexPropertyTests.cs b/test/Protobuf.System.Text.Json.Tests/MessageWithComplexPropertyTests.cs
index dcc9f8c..4d734ef 100644
--- a/test/Protobuf.System.Text.Json.Tests/MessageWithComplexPropertyTests.cs
+++ b/test/Protobuf.System.Text.Json.Tests/MessageWithComplexPropertyTests.cs
@@ -2,7 +2,6 @@
 using System.Text.Json.Protobuf.Tests;
 using System.Text.Json.Serialization;
 using Protobuf.System.Text.Json.Tests.Utils;
-using Shouldly;
 using SmartAnalyzers.ApprovalTestsExtensions;
 using Xunit;
 
@@ -51,7 +50,7 @@ public void Should_deserialize_message_with_complex_property()
         var deserialized = JsonSerializer.Deserialize<MessageWithComplexProperty>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldBeEquivalentTo(msg);
+        Assert.Equal(msg, deserialized);
     }
     
     [Fact]
@@ -74,6 +73,6 @@ public void Should_deserialize_message_with_complex_property_when_no_value_is_se
         var deserialized = JsonSerializer.Deserialize<MessageWithComplexProperty>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldBeEquivalentTo(msg);
+        Assert.Equal(msg, deserialized);
     }
 }
\ No newline at end of file
diff --git a/test/Protobuf.System.Text.Json.Tests/MessageWithDurationTests.cs b/test/Protobuf.System.Text.Json.Tests/MessageWithDurationTests.cs
index 64708ce..0c90420 100644
--- a/test/Protobuf.System.Text.Json.Tests/MessageWithDurationTests.cs
+++ b/test/Protobuf.System.Text.Json.Tests/MessageWithDurationTests.cs
@@ -2,7 +2,6 @@
 using System.Text.Json.Protobuf.Tests;
 using Google.Protobuf.WellKnownTypes;
 using Protobuf.System.Text.Json.Tests.Utils;
-using Shouldly;
 using SmartAnalyzers.ApprovalTestsExtensions;
 using Xunit;
 
@@ -60,8 +59,8 @@ public void Should_serialize_and_deserialize_message_with_duration()
         var deserialized = JsonSerializer.Deserialize<MessageWithDuration>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.ShouldBeEquivalentTo(msg);
+        Assert.NotNull(deserialized);
+        Assert.Equal(deserialized, msg);
     }
 
     [Fact]
@@ -76,8 +75,8 @@ public void Should_serialize_and_deserialize_message_with_duration_when_value_is
         var deserialized = JsonSerializer.Deserialize<MessageWithDuration>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.ShouldBeEquivalentTo(msg);
+        Assert.NotNull(deserialized);
+        Assert.Equal(deserialized, msg);
     }
 
     [Fact]
@@ -125,8 +124,7 @@ public void Should_deserialize_duration_property_from_complex_object_when_TreatD
         var deserialized = JsonSerializer.Deserialize<MessageWithDuration>(payload, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.ShouldBeEquivalentTo(msg);
-
+        Assert.NotNull(deserialized);
+        Assert.Equal(deserialized, msg);
     }
 }
\ No newline at end of file
diff --git a/test/Protobuf.System.Text.Json.Tests/MessageWithEnumFieldTests.cs b/test/Protobuf.System.Text.Json.Tests/MessageWithEnumFieldTests.cs
index 5ce93d6..e7cbcf3 100644
--- a/test/Protobuf.System.Text.Json.Tests/MessageWithEnumFieldTests.cs
+++ b/test/Protobuf.System.Text.Json.Tests/MessageWithEnumFieldTests.cs
@@ -1,7 +1,6 @@
 using System.Text.Json;
 using System.Text.Json.Protobuf.Tests;
 using Protobuf.System.Text.Json.Tests.Utils;
-using Shouldly;
 using SmartAnalyzers.ApprovalTestsExtensions;
 using Xunit;
 
@@ -42,8 +41,8 @@ public void Should_deserialize_message_with_with_enum_field()
         var deserialized = JsonSerializer.Deserialize<MessageWithEnum>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.ShouldBeEquivalentTo(msg);
+        Assert.NotNull(deserialized);
+        Assert.Equal(deserialized, msg);
     }
 
     [Fact]
@@ -106,8 +105,8 @@ public void Should_deserialize_message_with_enum_field_when_value_serialized_usi
         var deserialized = JsonSerializer.Deserialize<MessageWithEnum>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.ShouldBeEquivalentTo(msg);
+        Assert.NotNull(deserialized);
+        Assert.Equal(deserialized, msg);
     }
     
     [Fact]
@@ -127,6 +126,6 @@ public void Should_throw_exception_when_string_enum_value_cannot_be_deserialized
 
         // Act & Assert
         var exception = Assert.Throws<JsonException>(() => JsonSerializer.Deserialize<MessageWithEnum>(invalidPayload, jsonSerializerOptions));
-        exception.Message.ShouldContain("'INVALID_OPTION' is not a valid value for type System.Text.Json.Protobuf.Tests.TestEnum.");
+        Assert.Contains("'INVALID_OPTION' is not a valid value for type System.Text.Json.Protobuf.Tests.TestEnum.", exception.Message);
     }
 }
\ No newline at end of file
diff --git a/test/Protobuf.System.Text.Json.Tests/MessageWithMapsTests.cs b/test/Protobuf.System.Text.Json.Tests/MessageWithMapsTests.cs
index 3fbb86b..4c5831a 100644
--- a/test/Protobuf.System.Text.Json.Tests/MessageWithMapsTests.cs
+++ b/test/Protobuf.System.Text.Json.Tests/MessageWithMapsTests.cs
@@ -2,7 +2,6 @@
 using System.Text.Json.Protobuf.Tests;
 using Google.Protobuf;
 using Protobuf.System.Text.Json.Tests.Utils;
-using Shouldly;
 using SmartAnalyzers.ApprovalTestsExtensions;
 using Xunit;
 
@@ -59,7 +58,7 @@ public void Should_deserialize_message_with_map_field()
         var deserialized = JsonSerializer.Deserialize<MessageWithMaps>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.ShouldBeEquivalentTo(msg);
+        Assert.NotNull(deserialized);
+        Assert.Equal(deserialized, msg);
     }
 }
\ No newline at end of file
diff --git a/test/Protobuf.System.Text.Json.Tests/MessageWithOneOfTests.cs b/test/Protobuf.System.Text.Json.Tests/MessageWithOneOfTests.cs
index 1893a28..8f83bb3 100644
--- a/test/Protobuf.System.Text.Json.Tests/MessageWithOneOfTests.cs
+++ b/test/Protobuf.System.Text.Json.Tests/MessageWithOneOfTests.cs
@@ -1,7 +1,6 @@
 using System.Text.Json;
 using System.Text.Json.Protobuf.Tests;
 using Protobuf.System.Text.Json.Tests.Utils;
-using Shouldly;
 using SmartAnalyzers.ApprovalTestsExtensions;
 using Xunit;
 
@@ -58,10 +57,10 @@ public void Should_serialize_and_deserialize_message_with_one_of_when_value_is_s
         var deserialized = JsonSerializer.Deserialize<MessageWithOneOf>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.Int32PropertyValue.ShouldBe(msg.Int32PropertyValue);
-        deserialized.Int64PropertyValue.ShouldBe(msg.Int64PropertyValue);
-        deserialized.PropertyCase.ShouldBe(msg.PropertyCase);
+        Assert.NotNull(deserialized);
+        Assert.Equal(msg.Int32PropertyValue, deserialized.Int32PropertyValue);
+        Assert.Equal(msg.Int64PropertyValue, deserialized.Int64PropertyValue);
+        Assert.Equal(msg.PropertyCase, deserialized.PropertyCase);
     }
     
     [Fact]
@@ -76,10 +75,11 @@ public void Should_serialize_and_deserialize_message_with_one_of_when_value_is_n
         var deserialized = JsonSerializer.Deserialize<MessageWithOneOf>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.Int32PropertyValue.ShouldBe(msg.Int32PropertyValue);
-        deserialized.Int64PropertyValue.ShouldBe(msg.Int64PropertyValue);
-        deserialized.PropertyCase.ShouldBe(msg.PropertyCase);
+        Assert.NotNull(deserialized);
+        Assert.Equal(msg.Int32PropertyValue, deserialized.Int32PropertyValue);
+        Assert.Equal(msg.Int64PropertyValue, deserialized.Int64PropertyValue);
+        Assert.Equal(msg.PropertyCase, deserialized.PropertyCase);
+
     }
     
     [Fact]
@@ -132,9 +132,9 @@ public void Should_serialize_and_deserialize_message_with_optional_property_when
         var deserialized = JsonSerializer.Deserialize<MessageWithOptionalProperty>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.Int32Property.ShouldBe(msg.Int32Property);
-        deserialized.HasInt32Property.ShouldBe(msg.HasInt32Property);
+        Assert.NotNull(deserialized);
+        Assert.Equal(msg.Int32Property, deserialized.Int32Property);
+        Assert.Equal(msg.HasInt32Property, deserialized.HasInt32Property);
     }
     
     [Fact]
@@ -149,8 +149,8 @@ public void Should_serialize_and_deserialize_message_with_optional_property_when
         var deserialized = JsonSerializer.Deserialize<MessageWithOptionalProperty>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.Int32Property.ShouldBe(msg.Int32Property);
-        deserialized.HasInt32Property.ShouldBe(msg.HasInt32Property);
+        Assert.NotNull(deserialized);
+        Assert.Equal(msg.Int32Property, deserialized.Int32Property);
+        Assert.Equal(msg.HasInt32Property, deserialized.HasInt32Property);
     }
 }
\ No newline at end of file
diff --git a/test/Protobuf.System.Text.Json.Tests/MessageWithRepeatedListTests.cs b/test/Protobuf.System.Text.Json.Tests/MessageWithRepeatedListTests.cs
index 380328f..1bf39f9 100644
--- a/test/Protobuf.System.Text.Json.Tests/MessageWithRepeatedListTests.cs
+++ b/test/Protobuf.System.Text.Json.Tests/MessageWithRepeatedListTests.cs
@@ -1,7 +1,6 @@
 using System.Text.Json;
 using System.Text.Json.Protobuf.Tests;
 using Protobuf.System.Text.Json.Tests.Utils;
-using Shouldly;
 using SmartAnalyzers.ApprovalTestsExtensions;
 using Xunit;
 
@@ -62,11 +61,10 @@ public void Should_deserialize_message_with_repeated_list()
         var deserialized = JsonSerializer.Deserialize<MessageWithRepeatedList>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-
-        deserialized.Int32List.ShouldBe(msg.Int32List);
-        deserialized.Int64List.ShouldBe(msg.Int64List);
-        deserialized.EnumList.ShouldBe(msg.EnumList);
-        deserialized.NestedMessageList.ShouldBe(msg.NestedMessageList);
+        Assert.NotNull(deserialized);
+        Assert.Equal(msg.Int32List, deserialized.Int32List);
+        Assert.Equal(msg.Int64List, deserialized.Int64List);
+        Assert.Equal(msg.EnumList, deserialized.EnumList);
+        Assert.Equal(msg.NestedMessageList, deserialized.NestedMessageList);
     }
 }
\ No newline at end of file
diff --git a/test/Protobuf.System.Text.Json.Tests/MessageWithTimestampTests.cs b/test/Protobuf.System.Text.Json.Tests/MessageWithTimestampTests.cs
index db3557e..b3e46bb 100644
--- a/test/Protobuf.System.Text.Json.Tests/MessageWithTimestampTests.cs
+++ b/test/Protobuf.System.Text.Json.Tests/MessageWithTimestampTests.cs
@@ -4,7 +4,6 @@
 using System.Text.Json.Serialization;
 using Google.Protobuf.WellKnownTypes;
 using Protobuf.System.Text.Json.Tests.Utils;
-using Shouldly;
 using SmartAnalyzers.ApprovalTestsExtensions;
 using Xunit;
 
@@ -62,8 +61,8 @@ public void Should_serialize_and_deserialize_message_with_timestamp()
         var deserialized = JsonSerializer.Deserialize<MessageWithTimestamp>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.ShouldBeEquivalentTo(msg);
+        Assert.NotNull(deserialized);
+        Assert.Equal(msg, deserialized);
     }
     
     [Fact]
@@ -78,8 +77,8 @@ public void Should_serialize_and_deserialize_message_with_timestamp_when_value_i
         var deserialized = JsonSerializer.Deserialize<MessageWithTimestamp>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.ShouldBeEquivalentTo(msg);
+        Assert.NotNull(deserialized);
+        Assert.Equal(deserialized, msg);
     }
     
     [Fact]
@@ -95,7 +94,7 @@ public void Should_serialize_and_deserialize_message_with_timestamp_when_value_i
         var deserialized = JsonSerializer.Deserialize<MessageWithTimestamp>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.ShouldBeEquivalentTo(msg);
+        Assert.NotNull(deserialized);
+        Assert.Equal(deserialized, msg);
     }
 }
\ No newline at end of file
diff --git a/test/Protobuf.System.Text.Json.Tests/MessageWithWellKnownTypesTests.cs b/test/Protobuf.System.Text.Json.Tests/MessageWithWellKnownTypesTests.cs
index 6d55a6a..49a4084 100644
--- a/test/Protobuf.System.Text.Json.Tests/MessageWithWellKnownTypesTests.cs
+++ b/test/Protobuf.System.Text.Json.Tests/MessageWithWellKnownTypesTests.cs
@@ -2,7 +2,6 @@
 using System.Text.Json.Protobuf.Tests;
 using System.Text.Json.Serialization;
 using Protobuf.System.Text.Json.Tests.Utils;
-using Shouldly;
 using SmartAnalyzers.ApprovalTestsExtensions;
 using Xunit;
 
@@ -74,7 +73,8 @@ public void Should_serialize_and_deserialize_message_with_well_known_types_when_
 
 
         // Assert
-        deserialized.ShouldBe(msg);
+        Assert.Equal(msg, deserialized);
+
     }
 
     [Fact]
@@ -89,6 +89,6 @@ public void Should_serialize_and_deserialize_message_with_well_known_types_when_
         var deserialized = JsonSerializer.Deserialize<MessageWithWellKnownTypes>(serialized, jsonSerializerOptions);
         
         // Assert
-        deserialized.ShouldBe(msg);
+        Assert.Equal(msg, deserialized);
     }
 }
\ No newline at end of file
diff --git a/test/Protobuf.System.Text.Json.Tests/PropertyNameCaseInsensitiveTests.cs b/test/Protobuf.System.Text.Json.Tests/PropertyNameCaseInsensitiveTests.cs
index 764cfc3..266ebb0 100644
--- a/test/Protobuf.System.Text.Json.Tests/PropertyNameCaseInsensitiveTests.cs
+++ b/test/Protobuf.System.Text.Json.Tests/PropertyNameCaseInsensitiveTests.cs
@@ -1,6 +1,5 @@
 using System.Text.Json;
 using System.Text.Json.Protobuf.Tests;
-using Shouldly;
 using Xunit;
 
 namespace Protobuf.System.Text.Json.Tests;
@@ -30,6 +29,6 @@ public void Should_support_PropertyNameCaseInsensitive_setting()
         
         var deserialized = JsonSerializer.Deserialize<SimpleMessage>(payload, deserializerOptions);
         
-        deserialized.ShouldBeEquivalentTo(originalMessage);
+        Assert.Equal(originalMessage, deserialized);
     }
 }
\ No newline at end of file
diff --git a/test/Protobuf.System.Text.Json.Tests/SchemaEvolutionTests.cs b/test/Protobuf.System.Text.Json.Tests/SchemaEvolutionTests.cs
index 33d4949..46ad0c8 100644
--- a/test/Protobuf.System.Text.Json.Tests/SchemaEvolutionTests.cs
+++ b/test/Protobuf.System.Text.Json.Tests/SchemaEvolutionTests.cs
@@ -1,12 +1,9 @@
-using System;
-using System.Collections.Generic;
-using System.IO;
+using System.IO;
 using System.Linq;
 using System.Text.Json;
 using System.Text.Json.Protobuf.Tests;
 using System.Threading.Tasks;
 using Protobuf.System.Text.Json.Tests.Utils;
-using Shouldly;
 using Xunit;
 
 namespace Protobuf.System.Text.Json.Tests;
@@ -32,7 +29,8 @@ public void Should_be_able_to_deserialize_array_of_schema_v2_to_array_of_schema_
         var deserialized = JsonSerializer.Deserialize<SchemaEvolutionV1[]>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldHaveSingleItem();
+        Assert.NotNull(deserialized);
+        Assert.Single(deserialized);
     }
     
     [Fact]
@@ -54,7 +52,7 @@ public async Task Should_be_able_to_deserialize_array_of_schema_v2_to_array_of_s
         var deserialized = JsonSerializer.Deserialize<SchemaEvolutionV1[]>(memoryStream, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.Length.ShouldBe(schemaEvolutionV2.Count);
+        Assert.NotNull(deserialized);
+        Assert.Equal(schemaEvolutionV2.Count, deserialized.Length);
     }
 }
\ No newline at end of file
diff --git a/test/Protobuf.System.Text.Json.Tests/SimpleMessageTests.cs b/test/Protobuf.System.Text.Json.Tests/SimpleMessageTests.cs
index 6899cf9..6490fa6 100644
--- a/test/Protobuf.System.Text.Json.Tests/SimpleMessageTests.cs
+++ b/test/Protobuf.System.Text.Json.Tests/SimpleMessageTests.cs
@@ -2,7 +2,6 @@
 using System.Text.Json.Protobuf.Tests;
 using Google.Protobuf;
 using Protobuf.System.Text.Json.Tests.Utils;
-using Shouldly;
 using SmartAnalyzers.ApprovalTestsExtensions;
 using Xunit;
 
@@ -71,8 +70,8 @@ public void Should_deserialize_message_with_primitive_types()
         var deserialized = JsonSerializer.Deserialize<SimpleMessage>(serialized, jsonSerializerOptions);
 
         // Assert
-        deserialized.ShouldNotBeNull();
-        deserialized.Int32Property.ShouldBe(msg.Int32Property);
-        deserialized.Int64Property.ShouldBe(msg.Int64Property);
+        Assert.NotNull(deserialized);
+        Assert.Equal(msg.Int32Property, deserialized.Int32Property);
+        Assert.Equal(msg.Int64Property, deserialized.Int64Property);
     }
 }
\ No newline at end of file