Issue with OpenTofu tests against AWS Cloudfront Distributions [closed]

I could use an assist on my opentofu tests

Here is a small snippet of my Terraform module

resource "aws_cloudfront_distribution" "main" {
  price_class         = "PriceClass_All"
  aliases             = var.domain_addresses
  comment             = var.cloudfront_comment
  enabled             = true
  wait_for_deployment = true
  is_ipv6_enabled     = true

  default_cache_behavior {
    allowed_methods            = ["DELETE", "GET", "HEAD", "OPTIONS", "PATCH", "POST", "PUT"]
    cached_methods             = ["GET", "HEAD"]
    target_origin_id           = var.route_address
    compress                   = true
    viewer_protocol_policy     = "redirect-to-https"
    origin_request_policy_id   = var.origin_request_policy_name != "" ? data.aws_cloudfront_origin_request_policy.origin_policy[0].id : null
    cache_policy_id            = data.aws_cloudfront_cache_policy.cache_policy.id
    response_headers_policy_id = aws_cloudfront_response_headers_policy.policy.id
  }

  origin {
    domain_name = var.route_address
    origin_id   = var.route_address

    custom_origin_config {
      http_port              = 80
      https_port             = 443
      origin_protocol_policy = "https-only"
      origin_ssl_protocols   = ["TLSv1.2"]
    }
  }

  restrictions {
    geo_restriction {
      restriction_type = "none"
      locations        = []
    }
  }

  viewer_certificate {
    cloudfront_default_certificate = var.acm_certificate_arn == ""
    acm_certificate_arn            = var.acm_certificate_arn != "" ? var.acm_certificate_arn : null
    minimum_protocol_version       = var.minimum_protocol_version
    ssl_support_method             = "sni-only"
  }

  tags = merge(local.common_tags, var.extra_tags, {})
}

I am working on an opentofu test which checks for the domain name in the origin

variables {
  proxy_name        = "reverse-proxy"
  domain_addresses  = ["example.com", "www.example.com"]
  route53_zone_name = "example.com"
  route_address     = "cdn.example.com"
}

mock_provider "aws" {}

run "default" {
  assert {
    condition     = aws_cloudfront_distribution.main.origin[0].domain_name == "cdn.example.com"
    error_message = "Expected origin domain name to be 'cdn.example.com'"
  }
}

I am getting 2 errors

│ Error: Unknown variable
│ 
│   on cloudfront.tftest.hcl line 27, in run "default":
│   27:     condition     = aws_cloudfront_distribution.main.origin[0].domain_name == "cdn.example.com"
│ 
│ There is no variable named "aws_cloudfront_distribution".
╵
╷
│ Error: Cannot index a set value
│ 
│   on cloudfront.tftest.hcl line 27, in run "default":
│   27:     condition     = aws_cloudfront_distribution.main.origin[0].domain_name == "cdn.example.com"
│ 
│ Block type "origin" is represented by a set of objects, and set elements do not have addressable keys. To find elements matching specific criteria, use a "for" expression with an
│ "if" clause.

I am struggling trying to troubleshoot the issue, tried using --verbose and --json to try to get more information but not really anything pointing at why this is not working

Is there anything i can do to get more information, I'm sure its because origin is a set rather than an list but i am not sure what the set key would be to access it