Convert properties with underscores to PascalCase

src/Refitter.Core/CustomCSharpPropertyNameGenerator.cs

@@ -42,7 +42,9 @@ private static string ReplaceNameContainingReservedCharacters(JsonSchemaProperty
                 .Replace("+", "plus");
         }
 
-        name = ConversionUtilities.ConvertToUpperCamelCase(name, true);
+        name = ConversionUtilities
+            .ConvertToUpperCamelCase(name, true)
+            .ConvertSnakeCaseToPascalCase();
 
         if (name.IndexOfAny(ReservedSecondPassChars) != -1)
         {

src/Refitter.Tests/Examples/PercentageCharacterTests.cs

@@ -56,7 +56,7 @@ public async Task Can_Generate_Code()
     public async Task Replaces_Percentage_With_PascalCase()
     {
         string generateCode = await GenerateCode();
-        generateCode.Should().Contain("string Percent_of_something");
+        generateCode.Should().Contain("string PercentOfSomething");
     }
 
     [Fact]

src/Refitter.Tests/Examples/UnderscoresToPascalCaseTests.cs

@@ -0,0 +1,96 @@
+using FluentAssertions;
+using Refitter.Core;
+using Refitter.Tests.Build;
+using Xunit;
+
+namespace Refitter.Tests.Examples;
+
+public class HandleUnderscoresTests
+{
+    private const string OpenApiSpec = @"
+openapi: '3.0.0'
+info:
+  version: 'v1'
+  title: 'Test API'
+servers:
+  - url: 'https://test.host.com/api/v1'
+paths:
+  /jobs/{jobId}:
+    get:
+      tags:
+      - 'Jobs'
+      summary: 'Get job details'
+      description: 'Get the details of the specified job.'
+      parameters:
+        - in: 'path'
+          name: 'jobId'
+          description: 'Job ID'
+          required: true
+          schema:
+            type: 'string'
+      responses:
+        '200':
+          description: 'successful operation'
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/JobResponse'
+components:
+  schemas:
+    JobResponse:
+      type: 'object'
+      properties:
+        job:
+          type: 'object'
+          properties:
+            start_date:
+              type: 'string'
+              format: 'date-time'
+            details:
+              type: 'string'
+";
+
+    [Fact]
+    public async Task Can_Generate_Code()
+    {
+        string generateCode = await GenerateCode();
+        generateCode.Should().NotBeNullOrWhiteSpace();
+    }
+
+    [Fact]
+    public async Task Replaces_Underscore_Properties_With_PascalCase()
+    {
+        string generateCode = await GenerateCode();
+        generateCode.Should().Contain("DateTimeOffset StartDate");
+    }
+
+    [Fact]
+    public async Task Can_Build_Generated_Code()
+    {
+        string generateCode = await GenerateCode();
+        BuildHelper
+            .BuildCSharp(generateCode)
+            .Should()
+            .BeTrue();
+    }
+
+    private static async Task<string> GenerateCode()
+    {
+        var swaggerFile = await CreateSwaggerFile(OpenApiSpec);
+        var settings = new RefitGeneratorSettings { OpenApiPath = swaggerFile };
+
+        var sut = await RefitGenerator.CreateAsync(settings);
+        var generateCode = sut.Generate();
+        return generateCode;
+    }
+
+    private static async Task<string> CreateSwaggerFile(string contents)
+    {
+        var filename = $"{Guid.NewGuid()}.yml";
+        var folder = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString());
+        Directory.CreateDirectory(folder);
+        var swaggerFile = Path.Combine(folder, filename);
+        await File.WriteAllTextAsync(swaggerFile, contents);
+        return swaggerFile;
+    }
+}