I have a inputtext  in my VF page  as

        <apex:pageBlockSection >
         <apex:pageblockSectionItem >
          <apex:outputLabel for="searchText" style="font-size:14px">RefID/FileNumber</apex:outputLabel>
          <apex:panelGroup >
          <apex:inputText id="searchText" value="{!searchText}"/>
          <apex:commandButton value="Search" action="{!search}" rerender="resultsBlock" status="status"/>
          </apex:panelGroup>
         </apex:pageblockSectionItem>
        </apex:pageBlockSection>

I'm using that text field in my controller to compare one of my text field in the LeadBackup__c object as

public PageReference search() {
   // String qry = 'select id,Ref_ID_File_Number__c, Email__c, Phone__c, Street__c, City__c, State__c, TAB_Message__c, Evening_Phone__c, Preferred_Call_Time__c, Notes__c,DoNotCall__c from LeadBackup__c' + where Ref_ID_File_Number__c = searchText  order by name';
    searchResults1 = [select id,RefID_FileNumber__c,Name, Email__c, Phone__c, Street__c, City__c, State__c, TAB_Message__c, TAB_Time_stamp__c, Evening_Phone__c, Preferred_Call_Time__c, Notes__c,Do_Not_Call__c from LeadBackup__c where RefID_FileNumber__c =:searchText  order by name];
    //searchResults = Database.query(qry);
   
     
     //searchResults = [select id, name, FirstName, LastName, Status, Ref_ID_File_Number__c, Email, Phone, Street, City, State, Country, PostalCode, TAB_Message__c, Evening_Phone__c, Preferred_Call_Time__c, Notes__c,DoNotCall from Lead where Ref_ID_File_Number__c =:searchText  order by name];

   
    if(searchResults1.size()==0){

          LeadBackup__c lb = new  LeadBackup__c(RefID_FileNumber__c = searchText,
                                                Name=[select name,id from lead where Ref_ID_File_Number__c=:searchtext ].Name,
                                                City__c=[select name,id,city from lead where Ref_ID_File_Number__c=:searchtext ].City,
                                                Street__c=[select name,id,street from lead where Ref_ID_File_Number__c=:searchtext ].street,
                                                State__c=[select name,id,state from lead where Ref_ID_File_Number__c=:searchtext ].state,
                                                Lead__c = [select name,id from lead where Ref_ID_File_Number__c=:searchtext ].id,
                                                Email__c = [select name,id,Email from lead where Ref_ID_File_Number__c=:searchtext ].Email,
                                                Phone__c = [select name,id,Email,Phone from lead where Ref_ID_File_Number__c=:searchtext].Phone,
                                                Evening_Phone__c = [select name,id,Evening_Phone__c  from lead where                 Ref_ID_File_Number__c=:searchtext ].Evening_Phone__c,
                                                Preferred_Call_Time__c = [select name,id,Evening_Phone__c,Preferred_Call_Time__c   from lead where Ref_ID_File_Number__c=:searchtext ].Preferred_Call_Time__c,
                                                Notes__c = [select name,id,Evening_Phone__c,Notes__c   from lead where Ref_ID_File_Number__c=:searchtext ].Notes__c,
                                                Do_Not_Call__c = [select name,id,Evening_Phone__c,DoNotCall   from lead where Ref_ID_File_Number__c=:searchtext ].DoNotCall);
          //searchResults.add(lb);
          system.debug('lb'+lb);
          insert lb ;
          
          searchResults = [select id,RefID_FileNumber__c,Name, Email__c, Phone__c, Street__c, City__c, State__c, TAB_Message__c, TAB_Time_stamp__c, Evening_Phone__c, Preferred_Call_Time__c, Notes__c,Do_Not_Call__c from LeadBackup__c where RefID_FileNumber__c =:searchText  order by name];

          
    }else{
    
       ApexPages.addmessage(new ApexPages.message(ApexPages.severity.Info,'<b>Please confirm name and address below. Address will be where the letter was received/addressed. If these do not match, you will need to re-verify Ref ID, as it may have been entered incorrectly</b>'));
       
       searchResults = [select id,RefID_FileNumber__c,Name, Email__c, Phone__c, Street__c, City__c, State__c, TAB_Message__c, TAB_Time_stamp__c, Evening_Phone__c, Preferred_Call_Time__c, Notes__c,Do_Not_Call__c from LeadBackup__c where RefID_FileNumber__c =:searchText  order by name];

       return null;
    }
    return null;
  }
 
 
  public PageReference save() {
   
   if(!(String.isEmpty(searchText))){  -----------------From Here my code is not covering how to pass this search text in test class
          
       try {
            
            list<LeadBackup__c> lstupdate = new list<LeadBackup__c>();
            
                 
             For(LeadBackup__c le:searchResults){
             
             //le.Id = lead.Id;
             le.RefID_FileNumber__c = searchResults[0].RefID_FileNumber__c ;
             le.Lead__c = [select name,id from lead where Ref_ID_File_Number__c=:searchtext ].id;
             le.Name = searchResults[0].Name;
             le.Email__c = searchResults[0].Email__c;
             le.Phone__c = searchResults[0].Phone__c;
             le.Evening_Phone__c = searchResults[0].Evening_Phone__c ;
             le.Preferred_Call_Time__c = searchResults[0].Preferred_Call_Time__c;
             le.Notes__c = searchResults[0].Notes__c;
             le.Do_Not_Call__c = searchResults[0].Do_Not_Call__c;
             le.TAB_Message__c = True;
             le.TAB_Time_stamp__c = System.now();
             lstupdate.add(le);
             }
             
             update lstupdate;
      
      ApexPages.addmessage(new ApexPages.message(ApexPages.severity.info,'Record <b>'+searchResults[0].Name+'</b> has been Updated'));
            
    } Catch (DMLException e) {
      ApexPages.addMessages(e);
      return null;
    }
   
    searchText='';
    searchResults.clear();
    return null;
       
  }
  else
  {
       ApexPages.addmessage(new ApexPages.message(ApexPages.severity.info,'Please enter REFID/FileNumber'));
  }
 
  return null;
 
}

How to pass this search text to the test class ......

Any help would appreciated greatly...