asp.net-core - 填充 IConfiguration 以进行单元测试

Question

.NET Core 配置允许使用很多选项来添加值(环境变量、json 文件、命令行参数)。

我只是无法弄清楚并找到如何通过代码填充它的答案。

我正在为配置的扩展方法编写单元测试，我认为通过代码将其填充到单元测试中比为每个测试加载专用的 json 文件更容易。

我当前的代码:

[Fact]
public void Test_IsConfigured_Positive()
{

  // test against this configuration
  IConfiguration config = new ConfigurationBuilder()
    // how to populate it via code
    .Build();

  // the extension method to test
  Assert.True(config.IsConfigured());

}

更新:

一个特殊情况是“空部分”，在 json 中看起来像这样。

{
  "MySection": {
     // the existence of the section activates something triggering IsConfigured to be true but does not overwrite any default value
   }
 }

<小时/>

更新2:

正如 Matthew 在评论中指出的那样，json 中包含空部分与根本没有该部分的结果相同。我提炼了一个例子，是的，就是这样。我错误地期待着不同的行为。

那么我该怎么做以及我期望什么:

我正在为 IConfiguration 的 2 个扩展方法编写单元测试(实际上是因为 Get...Settings 方法中的值绑定(bind)由于某种原因不起作用(但那是另一个主题)。它们看起来像这样:

public static bool IsService1Configured(this IConfiguration configuration)
{
  return configuration.GetSection("Service1").Exists();
}

public static MyService1Settings GetService1Settings(this IConfiguration configuration)
{
  if (!configuration.IsService1Configured()) return null;

  MyService1Settings settings = new MyService1Settings();
  configuration.Bind("Service1", settings);

  return settings;
}

我的误解是，如果我在应用程序设置中放置一个空部分，IsService1Configured() 方法将返回 true (现在这显然是错误的)。我期望的不同之处在于，现在 GetService1Settings() 方法返回 null 为空部分，而不是像我期望的那样返回具有所有默认值的 MyService1Settings .

幸运的是，这仍然对我有用，因为我不会有空的部分(或者现在知道我必须避免这些情况)。这只是我在编写单元测试时遇到的一个理论案例。

进一步发展(对于那些感兴趣的人)。

我用它来做什么？基于配置的服务激活/停用。

我有一个应用程序，其中编译了一个服务/一些服务。根据部署，我需要完全激活/停用服务。这是因为某些(本地或测试设置)无法完全访问完整的基础设施(缓存、指标等帮助服务)。我通过应用程序设置来做到这一点。如果服务已配置(配置部分存在)，则会添加该服务。如果配置部分不存在，则不会使用它。

<小时/>

精简示例的完整代码如下。

• 在 Visual Studio 中从模板创建一个名为 WebApplication1 的新 API(无需 HTTPS 和身份验证)
• 删除 Startup 类和 appsettings.Development.json
• 将 Program.cs 中的代码替换为以下代码
• 现在，在 appsettings.json 中，您可以通过添加/删除 Service1 和 Service2 部分来激活/停用服务

using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;
using System;

namespace WebApplication1
{

  public class MyService1Settings
  {
  public int? Value1 { get; set; }
  public int Value2 { get; set; }
  public int Value3 { get; set; } = -1;
  }

  public static class Service1Extensions
  {

  public static bool IsService1Configured(this IConfiguration configuration)
  {
  return configuration.GetSection("Service1").Exists();
  }

  public static MyService1Settings GetService1Settings(this IConfiguration configuration)
  {
  if (!configuration.IsService1Configured()) return null;

  MyService1Settings settings = new MyService1Settings();
  configuration.Bind("Service1", settings);

  return settings;
  }

  public static IServiceCollection AddService1(this IServiceCollection services, IConfiguration configuration, ILogger logger)
  {

  MyService1Settings settings = configuration.GetService1Settings();

  if (settings == null) throw new Exception("loaded MyService1Settings are null (did you forget to check IsConfigured in Startup.ConfigureServices?) ");

  logger.LogAsJson(settings, "MyServiceSettings1: ");

  // do what ever needs to be done

  return services;
  }

  public static IApplicationBuilder UseService1(this IApplicationBuilder app, IConfiguration configuration, ILogger logger)
  {

  // do what ever needs to be done

  return app;
  }

  }

  public class Program
  {

    public static void Main(string[] args)
    {
      CreateWebHostBuilder(args).Build().Run();
    }

    public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
      WebHost.CreateDefaultBuilder(args)
      .ConfigureLogging
        (
        builder => 
          {
            builder.AddDebug();
            builder.AddConsole();
          }
        )
      .UseStartup<Startup>();
      }

    public class Startup
    {

      public IConfiguration Configuration { get; }
      public ILogger<Startup> Logger { get; }

      public Startup(IConfiguration configuration, ILoggerFactory loggerFactory)
      {
      Configuration = configuration;
      Logger = loggerFactory.CreateLogger<Startup>();
      }

      // This method gets called by the runtime. Use this method to add services to the container.
      public void ConfigureServices(IServiceCollection services)
      {

      // flavour 1: needs check(s) in Startup method(s) or will raise an exception
      if (Configuration.IsService1Configured()) {
      Logger.LogInformation("service 1 is activated and added");
      services.AddService1(Configuration, Logger);
      } else 
      Logger.LogInformation("service 1 is deactivated and not added");

      // flavour 2: checks are done in the extension methods and no Startup cluttering
      services.AddOptionalService2(Configuration, Logger);

      services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {

      if (env.IsDevelopment()) app.UseDeveloperExceptionPage();

      // flavour 1: needs check(s) in Startup method(s) or will raise an exception
      if (Configuration.IsService1Configured()) {
        Logger.LogInformation("service 1 is activated and used");
        app.UseService1(Configuration, Logger); }
      else
        Logger.LogInformation("service 1 is deactivated and not used");

      // flavour 2: checks are done in the extension methods and no Startup cluttering
      app.UseOptionalService2(Configuration, Logger);

      app.UseMvc();
    }
  }

  public class MyService2Settings
  {
    public int? Value1 { get; set; }
    public int Value2 { get; set; }
    public int Value3 { get; set; } = -1;
  }

  public static class Service2Extensions
  {

  public static bool IsService2Configured(this IConfiguration configuration)
  {
    return configuration.GetSection("Service2").Exists();
  }

  public static MyService2Settings GetService2Settings(this IConfiguration configuration)
  {
    if (!configuration.IsService2Configured()) return null;

    MyService2Settings settings = new MyService2Settings();
    configuration.Bind("Service2", settings);

    return settings;
  }

  public static IServiceCollection AddOptionalService2(this IServiceCollection services, IConfiguration configuration, ILogger logger)
  {

    if (!configuration.IsService2Configured())
    {
      logger.LogInformation("service 2 is deactivated and not added");
      return services;
    }

    logger.LogInformation("service 2 is activated and added");

    MyService2Settings settings = configuration.GetService2Settings();
    if (settings == null) throw new Exception("some settings loading bug occured");

    logger.LogAsJson(settings, "MyService2Settings: ");
    // do what ever needs to be done
    return services;
  }

  public static IApplicationBuilder UseOptionalService2(this IApplicationBuilder app, IConfiguration configuration, ILogger logger)
  {

    if (!configuration.IsService2Configured())
    {
      logger.LogInformation("service 2 is deactivated and not used");
      return app;
    }

    logger.LogInformation("service 2 is activated and used");
    // do what ever needs to be done
    return app;
  }
}

  public static class LoggerExtensions
  {
    public static void LogAsJson(this ILogger logger, object obj, string prefix = null)
    {
      logger.LogInformation(prefix ?? string.Empty) + ((obj == null) ? "null" : JsonConvert.SerializeObject(obj, Formatting.Indented)));
    }
  }

}

Answer 1

您可以使用MemoryConfigurationBuilderExtensions通过字典提供它。

using Microsoft.Extensions.Configuration;

var myConfiguration = new Dictionary<string, string>
{
    {"Key1", "Value1"},
    {"Nested:Key1", "NestedValue1"},
    {"Nested:Key2", "NestedValue2"}
};

var configuration = new ConfigurationBuilder()
    .AddInMemoryCollection(myConfiguration)
    .Build();

等效的 JSON 为:

{
  "Key1": "Value1",
  "Nested": {
    "Key1": "NestedValue1",
    "Key2": "NestedValue2"
  }
}

等效的环境变量是(假设没有前缀/不区分大小写):

Key1=Value1
Nested__Key1=NestedValue1
Nested__Key2=NestedValue2

等效的命令行参数是:

dotnet myapp.dll \
  -- \
  --Key1=Value1 \
  --Nested:Key1=NestedValue1 \
  --Nested:Key2=NestedValue2