Is there any way to Mock private method call inside another method in Junit5

Question

Below is the method which I wanted to test but as per my knowledge Junit5 doesn't support PowerMockito. So is there any way I can mock private method call inside another method ?

public Class MyClass {    


private void sendEmailNotification(Checklist Checklist){
    EmailService emailService = new EmailService();
    BaseDTO esDO = newFolderService.getFolderByUri(ServicesUtils.getDecodedCaseNodeUriFromSelfLink(Checklist.getEs_uri()));
    String esName = esDO.getName();
    SharedInfo sharedInfo = Checklist.getShared_info();
    sharedInfo.setEng_space_name(esName);
    String reviewer = Checklist.getReviewer();
    String ChecklistUri = Checklist.getUri();
    String ChecklistName = Checklist.getName();
    String targetPhase = Checklist.getTarget_phase();
    String comment = Checklist.getComment();
    String submitter = Checklist.getSubmitter();
    String appURL = Checklist.getShared_info().getApp_url();
    String ChecklistLink = buildChecklistURL(appURL, ChecklistUri);
    String emailBodyTemplate;
    String emailSubject;

      emailBodyTemplate = EmailTemplates.getEmailTemplateByName(EmailConstants.TEMPLATE_DELIVERABLE_ACCEPTED_REJECTED_WITH_COMMENTS);
      emailSubject = String.format(EmailConstants.ACCEPT_REJECT_WITH_COMMENTS_SUBJECT, ChecklistName, targetPhase);
      emailBodyTemplate = EmailTemplates.replaceSharedVariable(emailBodyTemplate, sharedInfo);
      emailBodyTemplate = EmailTemplates.replaceVariable(emailBodyTemplate, EmailConstants.VAR_TARGET_PHASE, targetPhase);
      emailBodyTemplate = EmailTemplates.replaceVariable(emailBodyTemplate, EmailConstants.VAR_REVIEWER, reviewer);
      emailBodyTemplate = EmailTemplates.replaceVariable(emailBodyTemplate, EmailConstants.VAR_CHECKLIST_ITEM_NAME, ChecklistName);
      emailBodyTemplate = EmailTemplates.replaceVariable(emailBodyTemplate, EmailConstants.VAR_COMMENT, comment);
      emailBodyTemplate = EmailTemplates.replaceVariable(emailBodyTemplate, EmailConstants.VAR_CHECKLIST_ITEM_URL, ChecklistLink);
    try {
      emailService.sendEmail(submitter, EmailConstants.EMAIL_SENDER, emailSubject, emailBodyTemplate);
    } catch (RuntimeException e) {
      Checklist.addError(messages.get(E_ACCEPT_REJECT_SEND_EMAIL));
    }

}

//Method to be tested

public void method(Checklist checklist){

  /*Some Code*/

  sendEmail(checklist);  /* want to ignore this, as throwing NullPointerException*/

  /*Some Code*/

}}

Answer 1

You are correct. Powermock does not yet support JUnit 5 and there is an open issue in their official github repository here.

There doesnt seem to be any easy way to mock private methods using Junit5 runner , unless of course you decide to use a custom classloader and do bytecode manipulation.

However, instead of mocking the whole method, I would suggest you to mock the dependency which is used to send the email (unless that dependency uses some final method).

And if you can't even do that, then best way is to use Junit4 instead of Junit5.