How to mock variables/methods which are added in src packages

[mioyn]

I have a common code in src folder, in package com.mycom.utils File : CommonStages.groovy Code:

    package com.mycom.utils
    def execute() {
      stage('some stage') {
        node ('someNode'){
          Println env.someenv
          
          }
         }
        }

Am getting no signature of method error com.mycom.utils.commonstages.stage() Is applicable for argument types: (java.lang.String, com.mycom.utils.commonsatges$_execute_closure1)

If the code is in jenkinsfile it executes but when I add it to the package structure it fails

test case using spock:

        def "common pipeline"() {
        given:
       

    when:

          helper.registerAllowedMethod('node', [Closure.class], null)
         helper.registerAllowedMethod("stage", [String.class], null)

         addEnvVar('PIPELINE_TYPE', 'PIPELINE_TYPE')
         def script = loadScript('Jenkinsfile')
        then:
        printCallStack()
      }