Missing association in trait leads to additional factory usage

Problem

In situations where we are using nested traits with association, it is ending up in using additional factory. It seems that we are having N+1 usage of factories. In the example below, we are using the :project factory two times.

Example

trait :with_jira_integration do
  has_external_issue_tracker { true }

  jira_integration
end

RSpec.describe "Foo" do
  it "creates a project" do
    create(:project, :with_jira_integration)
  end
end

Output

 Total: 6
 Total top-level: 2
 Total time: 00:01.603 (out of 00:15.824)
 Total uniq factories: 4

   total   top-level     total time      time per call      top-level time               name

       2           1        2.2575s            1.1288s             1.5919s            project
       2           0        0.4733s            0.2366s             0.0000s          namespace
       1           1        0.0115s            0.0115s             0.0115s            license
       1           0        0.8094s            0.8094s             0.0000s   jira_integration

Solution

We could use after :create strategy, which is conflicting with #262624:

Example

trait :with_jira_integration do
  has_external_issue_tracker { true }
  
  after :create do |project|
    create(:jira_integration, project: project)
  end
end

or we could go with interconnected-associations, which might require additional changes on a model or factory level due to validations:

trait :with_jira_integration do
  has_external_issue_tracker { true }

  jira_integration { association :jira_integration, project: instance }
end

Output

 Total: 4
 Total top-level: 2
 Total time: 00:00.871 (out of 00:14.044)
 Total uniq factories: 4

   total   top-level     total time      time per call      top-level time               name

       1           1        0.0075s            0.0075s             0.0075s            license
       1           1        0.8636s            0.8636s             0.8636s            project
       1           0        0.2771s            0.2771s             0.0000s          namespace
       1           0        0.1056s            0.1056s             0.0000s   jira_integration

/cc @splattael