Add support to GrailsApplicationBuilder(or GrailsUnitTest) to conditionally load external beans (from resources.groovy)

[HugoVega]

Grails team,

I'm currently writing unit test where I'm verifying a Camunda BPM process definition is correctly configured. The application defines multiple beans for different purposes including the multiple ones you need to make use of Camunda API declare in resources.groovy

A typical application resources.groovywould look like this:

beans = {
//Other bean deinition
 userPasswordEncoderListener(UserPasswordEncoderListener)
 authenticationEntryPoint(Http401AuthenticationEntryPoint, 'Bearer')
 logoutSuccessHandler(HttpStatusReturningLogoutSuccessHandler, HttpStatus.NO_CONTENT)
    


    //Camunda spring bean configuration
    identityProviderSessionFactory(SpringSecurityCorePluginSessionFactory)
    processEngineConfiguration(SpringProcessEngineConfiguration){
        processEngineName = "camunda-engine-${appName}-${Environment.currentEnvironment}"
        dataSource = ref("dataSource")
        databaseType = databaseUsing
        databaseSchemaUpdate = camundaSchemaStrategy
        transactionManager = ref("transactionManager")
        history = ProcessEngineConfiguration.HISTORY_DEFAULT
        jobExecutorActivate = jobExecutorEnabled
        customSessionFactories = [ref("identityProviderSessionFactory")]
    }

    processEngine(ProcessEngineFactoryBean){ bean ->
        processEngineConfiguration = ref("processEngineConfiguration")
    }

    runtimeService(processEngine: "getRuntimeService")
    taskService(processEngine: "getTaskService")
    identityService(processEngine: "getIdentityService")
    historyService(processEngine: "getHistoryService")
    formService(processEngine: "getFormService")
    managementService(processEngine: "getManagementService")
    filterService(processEngine: "getFilterService")
    externalTaskService(processEngine: "getExternalTaskService")
    caseService(processEngine: "getCaseService")
    decisionService(processEngine: "getDecisionService")
    repositoryService(processEngine: "getRepositoryService")
}

As you may see Camunda, requires a considerable amount of beans/code. Although you can create separated spring bean definition(doWithSpring(), xml, @Config ) for your unit test to declare only beans necessary for your test spec, it is better to use the same source to run the application(resources.groovy) and your test meeting with the DRY principle but the problem is that loadExternalBeanDefinion() loads all beans when for the purpose of testing, you only need to load a subset of what it is declared(in my case only Camunda Beans).

Is there any way to enhance GrailsUnitTest trait and/or GrailsApplicationBuilder class in order to enable a bean inclusion and/or exclusion Setsimilar to the plugin load feature already offered by Grails testing support?

For example:

class ProcessDefinitionSpec extends Specification implements AutowiredTest {
    Closure doWithSpring() {{ ->
        taskListener1(InstanceFactoryBean, Mock(ApprovalTaskListener))
    }}

   boolean loadExternalBeans() {true }
  
   Set<String> excludingBeans(){
        ["userPasswordEncoderListener", "authenticationEntryPoint", "logoutSuccessHandler"]. toSet()
   }

   // ALL TEST BELOW HERE
}

or using an inclusion Set:

class ProcessDefinitionSpec extends Specification implements AutowiredTest {
    Closure doWithSpring() {{ ->
        taskListener1(InstanceFactoryBean, Mock(ApprovalTaskListener))
    }}

   boolean loadExternalBeans() {true }
  
   Set<String> includinglBeans(){
      ["identityProviderSessionFactory", "processEngineConfiguration", "processEngine", "runtimeService", "taskService", "repositoryService"]. toSet()
   }

   // ALL TEST BELOW HERE
}

I hope I explain the use case well!

Saludos
Hugo