override-configuration-value.md

Override configuration values on the test server

• Summary
• Motivation
• Requirements
• How to use
• Hierarchical configuration values
• Alternatives
• IWebHostBuilder.SetSetting
• IServiceCollection.PostConfigure

Summary

This extension allows you to do set configuration values for integration tests. It works for both IWebHostBuilder and IHostBuilder.

Motivation

I want to be able to do integration tests as defined in introduction to integration tests and I need to be able to control the configuration for the tests.

In Providing test appsettings files to the test server we show a way to provide entire appsettings values to the configuration of the test server. However, in some cases you might want to provide only some configuration values or provide the full appsettings but override some values.

Requirements

You will have to add the dotnet-sdk-extensions-testing nuget to your test project.

How to use

Start by creating an integration test as shown in introduction to integration tests. After you can set configuration values as follows:

public class ConfigurationDemoTests : IClassFixture<WebApplicationFactory<Progam>>
{
    private readonly WebApplicationFactory<Progam> _webApplicationFactory;

    public ConfigurationDemoTests(WebApplicationFactory<Progam> webApplicationFactory)
    {
        _webApplicationFactory = webApplicationFactory;
    }

    [Fact]
    public async Task DemoTest()
    {
        var httpClient = _webApplicationFactory
            .WithWebHostBuilder(builder =>
            {
                builder
                    .UseConfigurationValue(key: "SomeConfigOption", value: "some-option-value")
                    .ConfigureTestServices(services =>
                    {
                        // inject mocks for any other services
                    });
            })
            .CreateClient();

        // rest of test
    }
}

You can call the method several times to configure multiple values.

Optionally you can use the method provided in Providing test appsettings files to the test server and then override some configuration values:

public class ConfigurationDemoTests : IClassFixture<WebApplicationFactory<Progam>>
{
    private readonly WebApplicationFactory<Progam> _webApplicationFactory;

    public ConfigurationDemoTests(WebApplicationFactory<Progam> webApplicationFactory)
    {
        _webApplicationFactory = webApplicationFactory;
    }

    [Fact]
    public async Task DemoTest()
    {
        var httpClient = _webApplicationFactory
            .WithWebHostBuilder(builder =>
            {
                builder
                    .AddTestConfiguration("appsettings.json")
                    .UseConfigurationValue(key: "SomeOption", value: "some-option-value")
                    .ConfigureTestServices(services =>
                    {
                        // inject mocks for any other services
                    });
            })
            .CreateClient();

        // rest of test
    }
}

Hierarchical configuration values

You can also set the values for hierarchical configuration by using the : separator.

For instance, if we have the following appsettings.json:

"MyOptionsSection": {
    "SomeOption": "Hello from configuration"
  }

You can set the configuration value for SomeOption by calling:

builder.UseConfigurationValue(key: "MyOptionsSection:SomeOption", value: "some-option-value")

Alternatives

IWebHostBuilder.SetSetting

If you are using a IWebHostBuilder then you can make use of the IWebHostBuilder.SetSetting as follows:

public class ConfigurationDemoTests : IClassFixture<WebApplicationFactory<Progam>>
{
    private readonly WebApplicationFactory<Progam> _webApplicationFactory;

    public ConfigurationDemoTests(WebApplicationFactory<Progam> webApplicationFactory)
    {
        _webApplicationFactory = webApplicationFactory;
    }

    [Fact]
    public async Task DemoTest()
    {
        var httpClient = _webApplicationFactory
            .WithWebHostBuilder(builder =>
            {
                builder.SetSetting(key: "SomeOption", value: "some-option-value")
                builder.ConfigureTestServices(services =>
                {
                    // inject mocks for any other services
                });
            })
            .CreateClient();

        // rest of test
    }
}

This method does not exist on the IHostBuilder.

IServiceCollection.PostConfigure

If you are using typed options classes you can also override the configuration values on those types by using the IServiceCollection.PostConfigure.

Let's say you have an options classed defined by the type MyOptions as follows:

public class MyOptions
{
    public string SomeOption { get; set; }
}

And that you are binding the MyOptions type in the service collection. If you want to set the value of the MyOptions.SomeOption for an integration test you can do as follows:

public class ConfigurationDemoTests : IClassFixture<WebApplicationFactory<Progam>>
{
    private readonly WebApplicationFactory<Progam> _webApplicationFactory;

    public ConfigurationDemoTests(WebApplicationFactory<Progam> webApplicationFactory)
    {
        _webApplicationFactory = webApplicationFactory;
    }

    [Fact]
    public async Task DemoTest()
    {
        var httpClient = _webApplicationFactory
            .WithWebHostBuilder(builder =>
            {
                builder.ConfigureTestServices(services =>
                {
                    services.PostConfigure<MyOptions>(myOptions =>
                    {
                        myOptions.SomeOption = "configured-value-in-test";
                    });
                    // inject mocks for any other services
                });
            })
            .CreateClient();

        // rest of test
    }
}