[BUG] [aspnetcore] Swagger XML comments causes issues for test project

[david-marconis]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

The generated code for aspnetcore with swagger generation (Swashbuckle) enabled uses the GetEntryAssembly method to specify the path to the XML comments. This causes issues if you were to test this API from a different project (assembly) as the entry assembly will be the test project and not the main project.

There is an easy workaround to this and that is to use GetExecutingAssembly instead of GetEntryAssebly which is also what Microsoft recommends:

builder.Services.AddSwaggerGen(options =>
{
    options.SwaggerDoc("v1", new OpenApiInfo
    {
    ...
    // using System.Reflection;
    var xmlFilename = $"{Assembly.GetExecutingAssembly().GetName().Name}.xml";
    options.IncludeXmlComments(Path.Combine(AppContext.BaseDirectory, xmlFilename));
});

openapi-generator version

7.8.0

OpenAPI declaration file content or url

openapi: 3.0.0
info:
  title: Minimal API
  version: 1.0.0
paths:
  /example:
    get:
      summary: A minimal GET endpoint
      responses:
        '200':
          description: "Success"
          content:
            application/json:
              schema:
                type: object
                properties:
                  message:
                    type: string

Generation Details

openapi-generator-cli generate -i openapi.yaml -g aspnetcore

Steps to reproduce

cat <<EOF > openapi.yaml
openapi: 3.0.0
info:
  title: Minimal API
  version: 1.0.0
paths:
  /example:
    get:
      summary: A minimal GET endpoint
      responses:
        '200':
          description: "Success"
          content:
            application/json:
              schema:
                type: object
                properties:
                  message:
                    type: string
EOF
openapi-generator-cli generate -i openapi.yaml -g aspnetcore
dotnet new xunit -n Tests -o src/Org.OpenAPITools.Tests
dotnet add src/Org.OpenAPITools.Tests reference src/Org.OpenAPITools
dotnet add src/Org.OpenAPITools.Tests package Microsoft.AspNetCore.Mvc.Testing
cat <<EOF > src/Org.OpenAPITools.Tests/UnitTest1.cs
using System.Net;
using Microsoft.AspNetCore.Mvc.Testing;
using Org.OpenAPITools.Controllers;

namespace Tests;

public class ApiTest(WebApplicationFactory<DefaultApiController> factory)
    : IClassFixture<WebApplicationFactory<DefaultApiController>>
{
    private readonly HttpClient _httpClient = factory.CreateClient();

    [Fact]
    public async void TestApi()
    {
        var response = await _httpClient.GetAsync("example/");
        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
    }
}
EOF
dotnet test src/Org.OpenAPITools.Tests

Observe test failure:

[xUnit.net 00:00:00.27] Tests.ApiTest.TestApi [FAIL]
Failed Tests.ApiTest.TestApi [171 ms]
Error Message:
Assert.Equal() Failure: Values differ
Expected: OK
Actual: InternalServerError

Apply simple fix, using GetExecutingAssembly instead of GetEntryAssembly, and rerun test:

sed 's/GetEntryAssembly/GetExecutingAssembly/' -i src/Org.OpenAPITools/Startup.cs
dotnet test src/Org.OpenAPITools.Tests

Observe test passing:

Passed! - Failed: 0, Passed: 1, Skipped: 0, Total: 1, Duration: < 1 ms - Tests.dll (net8.0)

Related issues/PRs

Suggest a fix

Use GetExecutingAssembly instead.
Fixed by merging #19593