.NET Core配置允许添加许多选项以添加值（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。
我正在为配置扩展方法编写单元测试，我认为通过代码在单元测试中填充它比为每个测试加载专用的json文件更容易。
我的当前代码：
[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：
特殊情况之一是“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
}
}
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;
}
我曾经误解，如果我在appsettings中放置一个空的部分，IsService1Configured()方法将会返回true（现在显然是错误的）。我预期的差异是，现在有了一个空的部分，GetService1Settings()方法将返回null，而不是我预期的带有所有默认值的MyService1Settings。
幸运的是，这对我仍然有效，因为我不会有空的部分（或者现在我知道我必须避免这种情况）。这只是我在编写单元测试时遇到的一个理论案例。
下面是更进一步的讨论（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，其中包含编译成其中的一个或多个服务。根据部署环境，我需要完全激活/停用服务。这是因为一些（本地或测试设置）没有完全访问完整的基础架构（像缓存、指标之类的辅助服务）。我通过appsettings来实现这一点。如果服务被配置了（存在配置部分），它将被添加。如果不存在配置部分，则不会使用它。
以下是精简示例的完整代码。
- 在Visual Studio中从模板创建一个名为WebApplication1的新API（不带HTTPS和身份验证）
- 删除Startup类和appsettings.Development.json
- 将Program.cs中的代码替换为下面的代码
- 现在，您可以通过添加/移除
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)));
}
}
}