how do I override configuration for integration tests using DistributedApplicationFactory?

[chalcolith]

I am trying to override a parameter for integration tests via DistributedApplicationFactory.OnBuilderCreating(). However, trying to override the parameter via either hostOptions.Args or hostOptions.Configuration never works. (For some reason overriding a connection string via Args works, but not Configuration.)

I have the following Aspire app host code:

var builder = DistributedApplication.CreateBuilder(args);

var database = builder.AddConnectionString("mydatabase");
var parameter = builder.AddParameter("myparameter", "false");

builder.AddProject<Projects.MyProject_Web>("mywebsite")
    .WithEnvironment("MY_PARAMETER", "myparameter")
    .WithExternalHttpEndpoints()
    .WithReference("mydatabase");

Then I have an implementation of DistributedApplicationFactory for use with integration tests, where I try to override the parameter in various unsuccessful ways:

internal sealed class TestAppHost() : DistributedApplicationFactory(typeof(Projects.MyProject_Web))
{
    protected override void OnBuilderCreating(
        DistributedApplicationOptions applicationOptions,
        HostApplicationBuilderSettings hostOptions)
    {
        base.OnBuilderCreating(applicationOptions, hostOptions);

        applicationOptions.AllowUnsecuredTransport = true;
        applicationOptions.DisableDashboard = true;

        hostOptions.Args =
            [
                @"Parameters:myparameter=true", // doesn't show up in WebApplicationBuilder
                @"MY_PARAMETER=true", // isn't changed in WebApplicationBuilder
                @"ConnectionStrings:mydatabase=<my_integration_test_db_connection_string>", // this IS changed in WebApplicationBuilder
            ];

        hostOptions.EnvironmentName = "Development";

        hostOptions.Configuration ??= new();
        hostOptions.Configuration["Parameters:myparameter"] = "true"; // doesn't show up in WebApplicationBuilder
        hostOptions.Configuration["MY_PARAMETER"] = "true"; // isn't changed in WebApplicationBuilder
        hostOptions.Configuration["ConnectionStrings:mydatabase"] = @"my_integration_test_db_connection_string"; // is not changed in WebApplicationBuilder
    }
}

The parameter is never changed in my web application builder:

var builder = WebApplication.CreateBuilder(args);
var myParameterVal = builder.Configuration["MY_PARAMETER"]; // is always "false", when it should be "true" for integration tests

I have also tried the equivalent in constructing a DistributedApplicationTestingBuilder, with the same results.

What am I doing wrong? How can I override a parameter for my integration tests?

[davidfowl]

Can't you just set the configuration directly after creating the DistributedApplicationTestingBuilderv via the Configuration property?

[davidfowl]

You would do this:

var builder = await DistributedApplicationTestingBuilder.CreateAsync();

builder.Configuration["Parameters:myparameter"] = "true";

This should work.

[chalcolith]

Unfortunately it doesn't work for me.

[davidfowl]

Can you share a project that reproduces the problem, maybe we have a bug

[chalcolith]

Sure thing: https://github.com/chalcolith/aspire_parameter_override

[mrfelton]

I also seem to be unable to override the config in any of these ways.

Only way I have been able to get it to work is by setting environment variables before calling CreateAsync

Environment.SetEnvironmentVariable("Some__Setting", "value");

I wou;d have thought this would work, but it does not.

var appBuilder = await DistributedApplicationTestingBuilder.CreateAsync<global::Program>(
	[],
	(applicationOptions, hostOptions) => {
		applicationOptions.DisableDashboard = true;

		// Configure host options for testing environment
		hostOptions.EnvironmentName = "Testing";

		if (hostOptions.Configuration is not null) {
			hostOptions.Configuration.AddInMemoryCollection(new Dictionary<string, string?> {
				{ "DockerHost:Infrastructure:EnableRabbitMQ", "true" },
				{ "DockerHost:Infrastructure:EnablePostgres", "true" },
				{ "DockerHost:Infrastructure:EnableRedis", "false" },
			});
		}
	});