Using user secrets in integration test

To use user secrets in an integration test, do the following:

• install Microsoft.Extensions.Configuration.UserSecrets in the test project.
• copy the UserSecretsId from the startup project.
• build a new Configuration in the test Setup().
• use the Configuration as usual in the test(s).

<PropertyGroup>
  <UserSecretsId>B4C6D3C1-2DE0-44B6-AFA8-8891DC665913</UserSecretsId>
</PropertyGroup>

[SetUp]
public void Setup()
{
    // Needs Microsoft.Extensions.Configuration.UserSecrets NuGet package.
    // To use the same secrets file as the main application, copy
    // the <UserSecretsId> from the startup projects .csproj file to the
    // .csproj file for this test assembly.
    var builder = new ConfigurationBuilder()
        .AddUserSecrets<SmsServiceIntegrationTests>();

    Configuration = builder.Build();
}

var integrationTestPhoneNumber = Configuration["AppSettings:SmsMessaging:IntegrationTestPhoneNumber"];