Add support for generating IServiceCollection extension methods for registering Refit clients

[christianhelle]

Use case:

I'm too lazy to setup my Refit clients in using HttpClientFactory and I want all this bootstrapping code written for me

Example OpenAPI spec:

openapi: '3.0.0'
paths:
  /foo/{id}:
    delete:
      tags:
      - 'Foo'
      operationId: 'Delete foo'
      description: 'Delete the specified foo'
      parameters:
        - in: 'path'
          name: 'id'
          description: 'Foo ID'
          required: true
          schema:
            type: 'string'
      responses:
        '200':
          description: 'successful operation'

.refitter settings file

{
  "openApiPath": "openapi.yaml",
  "multipleInterfaces": "ByEndpoint",
  "dependencyInjectionSettings": {
    "baseUrl": "https://example.com/api/v3",
    "usePolly": true
  }
}

Generated code:

namespace GeneratedCode
{
    [System.CodeDom.Compiler.GeneratedCode("Refitter", "1.0.0.0")]
    public partial interface IDeleteFooEndpoint
    {
        /// <summary>
        /// Delete the specified foo
        /// </summary>
        [Delete("/foo/{id}")]
        Task Execute(string id);
    }
}

namespace GeneratedCode
{
    using System;
    using Microsoft.Extensions.DependencyInjection;
    using Polly;
    using Polly.Contrib.WaitAndRetry;
    using Polly.Extensions.Http;

    public static class ServiceCollectionExtensions
    {
        public static IServiceCollection ConfigureRefitClients(this IServiceCollection services)
        {
            services
                .AddRefitClient<IDeleteFooEndpoint>()
                .ConfigureHttpClient(c => c.BaseAddress = new Uri("https://example.com/api/v1"))
                .AddPolicyHandler(
                    HttpPolicyExtensions
                        .HandleTransientHttpError()
                        .WaitAndRetryAsync(
                            Backoff.DecorrelatedJitterBackoffV2(
                                TimeSpan.FromSeconds(1),
                                6)));

            return services;
        }
    }
}

Example usage of generated code:

using Refit;
using GeneratedCode;

var builder = WebApplication.CreateBuilder(args);
builder.Services.ConfigureRefitClients();

var app = builder.Build();
app.MapDelete(
        "/foo/{id:int}",
        async (IDeleteFooEndpoint endpoint, int id) =>
        {
            try
            {
                return Results.Ok(await endpoint.Execute(id));
            }
            catch (ApiException e)
            {
                return Results.StatusCode((int)e.StatusCode);
            }
        })
    .WithName("DeleteFoo")
    .WithOpenApi();

app.Run();

Using HttpMessageHandlers

The changes here also support adding existing HttpMessageHandler implementations to the Refit client by specifying "httpMessageHandlers" it in the .refitter settings

{
  "openApiPath": "openapi.yaml",
  "multipleInterfaces": "ByEndpoint",
  "dependencyInjectionSettings": {
    "baseUrl": "https://example.com/api/v3",
    "usePolly": true,
    "httpMessageHandlers": [ "AuthorizationMessageHandler", "TelemetryMessageHandler" ]
  }
}

Which would generate the following:

namespace GeneratedCode
{
    using System;
    using Microsoft.Extensions.DependencyInjection;
    using Polly;
    using Polly.Contrib.WaitAndRetry;
    using Polly.Extensions.Http;

    public static class ServiceCollectionExtensions
    {
        public static IServiceCollection ConfigureRefitClients(this IServiceCollection services)
        {
            services
                .AddRefitClient<IDeleteFooEndpoint>()
                .ConfigureHttpClient(c => c.BaseAddress = new Uri("https://example.com/api/v1"))
                .AddHttpMessageHandler<AuthorizationMessageHandler>()
                .AddHttpMessageHandler<TelemetryMessageHandler>()
                .AddPolicyHandler(
                    HttpPolicyExtensions
                        .HandleTransientHttpError()
                        .WaitAndRetryAsync(
                            Backoff.DecorrelatedJitterBackoffV2(
                                TimeSpan.FromSeconds(1),
                                6)));

            return services;
        }
    }
}

The generate IServiceCollection methods above require that the specified HttpMessageHandler implementations are already registered to the IoC container

[codecov]

Codecov Report

Merging #174 (1b4adfc) into main (54a9b90) will increase coverage by 0.33%.
Report is 5 commits behind head on main.
The diff coverage is 100.00%.

❗ Current head 1b4adfc differs from pull request most recent head 8461a77. Consider uploading reports for the commit 8461a77 to get more accurate results

@@            Coverage Diff             @@
##             main     #174      +/-   ##
==========================================
+ Coverage   98.37%   98.70%   +0.33%     
==========================================
  Files          41       47       +6     
  Lines        1353     1626     +273     
==========================================
+ Hits         1331     1605     +274     
  Misses          6        6              
+ Partials       16       15       -1     

Flag	Coverage Δ
unittests	98.70% <100.00%> (+0.33%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
src/Refitter.Core/DependencyInjectionGenerator.cs	100.00% <100.00%> (ø)
src/Refitter.Core/RefitGeneratedCode.cs	100.00% <100.00%> (ø)
src/Refitter.Core/RefitGenerator.cs	99.35% <100.00%> (+0.02%)	⬆️
src/Refitter.Core/RefitGeneratorSettings.cs	100.00% <100.00%> (ø)
src/Refitter.Core/RefitInterfaceGenerator.cs	100.00% <100.00%> (ø)
...itter.Core/RefitMultipleInterfaceByTagGenerator.cs	94.28% <100.00%> (+1.74%)	⬆️
...c/Refitter.Core/RefitMultipleInterfaceGenerator.cs	100.00% <100.00%> (ø)
...efitter.Tests/DependencyInjectionGeneratorTests.cs	100.00% <100.00%> (ø)
...atedMultipleInterfaceByTagEndpointsSkippedTests.cs	100.00% <100.00%> (ø)
...amples/MultipleInterfacesByEndpointWithIoCTests.cs	100.00% <100.00%> (ø)
... and 1 more

[christianhelle]

You might find this interesting @Noblix

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

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