I have a controller that has the following lines of code. (abbreviated for example purposes)

public  with sharing class  myReferralController2  {

public string   CaseAppMonth(string mymonth) {
  string mynumbermonth;
 
   if    (mymonth == 'Jan') {
          mynumbermonth ='1';    }
      else
       if (mymonth == 'Feb') {
           mynumbermonth ='2';    }
      else
       if  (mymonth == 'Mar') {
            mynumbermonth ='3';    }
    if      (mymonth == 'Apr') {
           mynumbermonth ='4';    }
      else
       if (mymonth == 'May') {
          mynumbermonth ='5';    }
      else
       if (mymonth == 'Jun') {
           mynumbermonth ='6';    }
      else
       if (mymonth == 'Jul') {
          mynumbermonth ='7';    }
      else
       if (mymonth == 'Aug') {
           mynumbermonth ='8';    }
       else
       if (mymonth == 'Sep') {
           mynumbermonth ='9';    }
      else
       if  (mymonth == 'Oct') {
            mynumbermonth ='10';    }
      if   (mymonth == 'Nov') {
            mynumbermonth ='11';    }
      if   (mymonth == 'Dec') {
            mynumbermonth ='12';    }
      
 
   return mynumbermonth;                       }

my unit test is something like this:

myReferralController2 cc1 = new  myReferralController2();
              cc1.NewReferralClientc.Client_Rep_ID__c='DEC79EN';
           .      .
.           cc1.getChooseReferral();
           cc1.ReferralType='Engagement';
           List<SelectOption> ChoosePartner =    cc1.getChoosePartner();
           cc1.PartnerProviderType = 'TNCSA';
           List <string> appointmentlist1 = cc1.getlistappointments();
                                            cc1.getDateAppointmentsListValue();
         list <SELECTOPTION> options = cc1.getDateAppointmentsoptions();
                                     cc1.AddDateTime();
                 
                                    cc1.IsDateAndTimeSelected();
                                    cc1.norefresh();
                               
           cc1.NewReferralClientc.Client_Rep_ID__c  = 'DEC79EN';
           cc1.ClientFirstName  = 'Bob';
           cc1.ClientLastName = 'Smith';
           cc1.ClientLastFour ='0900';
           cc1.ClientPhone ='2152345677';
               
        
           string numbermonth = cc1.CaseAppMonth('Jun');
           system.assertequals('6',numbermonth);
         

When I  run the Unit test I don't see any increase in coverage.

Can you show me how to cover the if else branch and how to call caseappMonth?

Thank You