无法读取数据appsettings.json文件

我肯定我出了点毛病,但我看不出来,对不起。进入启动代码提示appsettings.json文件正在正确加载,但测试类随后会为config类获取null。

启动:

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        var builder = new ConfigurationBuilder().AddJsonFile("appSettings.json");
        Configuration = builder.Build();
    }

    public IConfiguration Configuration { get; set; }

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMvc().AddSessionStateTempDataProvider();
        services.AddSession();

        services.Configure<EnvironmentConfig>(Configuration.GetSection("EnvironmentConfig"));
    }
}

配置测试仪:

public class ConfigTester
{
    private readonly IOptions<EnvironmentConfig> _environmentConfig;

    public ConfigTester(IOptions<EnvironmentConfig> environmentConfig)
    {
        _environmentConfig = environmentConfig;
    }

    public string ConfigName()
    {
        return _environmentConfig.Value.Name;         //_environmentConfig.Value is set, but Name is null
    }
}

public class EnvironmentConfig
{
    public string Name;

}

appSettings.json文件:

{
  "Logging": {
    "IncludeScopes": false,
    "Debug": {
      "LogLevel": {
        "Default": "Warning"
      }
    },
    "Console": {
      "LogLevel": {
        "Default": "Warning"
      }
    }
  },
  "EnvironmentConfig": {
    "Name": "develop"
  }
}

我错过了什么?