LeadTrigger with Custom Metadata

trigger LeadTrigger on Lead (After Update) {
    Map<Id, Lead> leadsToUpdate = new Map<Id, Lead>();
    
    List<Competitor__mdt> competitorRecords = [Select Label from Competitor__mdt];//Retrieve our Custom Metadata Records
    List<String> competitorNames = new List<String>();//Instantiate an empty list to hold the names of our competitors
    for(Competitor__mdt record : competitorRecords){//Loop through the Custom Metadata records our query returned
        competitorNames.add(record.Label);//Add them to our empty list
    }
    
    for(Integer i = 0 ; i < trigger.new.size() ; i++){
        Lead old = trigger.old[i];
        Lead nw = trigger.new[i];
        
        if(old.Status != nw.Status && nw.Status == 'Closed - Not Converted'){
            Lead myLead = new Lead(Id = nw.Id, Rating = 'Cold'); 
            leadsToUpdate.put(nw.Id, myLead);
        }
        
        //put this inside your Lead Trigger's for loop, after the first if condition ends

		if(old.Company != nw.Company && competitorNames.contains(nw.Company)){ //Use the .contains() List Method to check if the Company field is in the Competitors Custom Metadata
            if(leadsToUpdate.containsKey(nw.id)){
                leadsToUpdate.get(nw.Id).DoNotCall = True;
            } else {//If the map doesn't contain the record ID...
                Lead myLead = new Lead(Id = nw.Id, DoNotCall = true);
                leadsToUpdate.put(nw.Id, myLead);
            }
        }
    }
    
    if(leadsToUpdate.size() > 0){
        update leadstoUpdate.values();
    }

}

LeadTriggerTest with Custom Metadata

@isTest
public class LeadTriggerTest {
    public static List<String> competitorNames = new List<String>();
    public static List<Lead> leadsToInsert = new List<Lead>();
    
    public static void createTestData(){        
        //Use a for loop to prepare multiple Leads
        for(Integer i = 0 ; i < 2 ; i++){
            Lead myLead = new Lead();
            myLead.LastName = 'Lead Last Name' + i;
            myLead.Company = 'Lead Company' + i;
            leadsToInsert.add(myLead);
        }
        insert leadsToInsert;//Insert our test data
        
        for(Competitor__mdt record : [Select Label from Competitor__mdt]){
            competitorNames.add(record.Label);
        }        
        System.debug('from setup' + competitorNames);
        
    }
    
    public static testMethod void testManyClosedNotConverted(){
        createTestData();
        
        List<Lead> leadsToUpdate = new List<Lead>();//Create a List to update our leads in bulk
        
        //Use a for loop to prepare our updates
        for(Lead l : leadsToInsert){
            l.Status = 'Closed - Not Converted';
            leadsToUpdate.add(l);
        }
        
        test.startTest();//Start our actual test, updating our records
        update leadsToUpdate;//issue update call
        test.stopTest();
        
        
        List<Lead> testLeads = [Select Rating from Lead];//Query for Leads, getting the field updated by our Lead Trigger
        
        //Use a for loop to check each Lead
        for(Lead l : testLeads){
            System.assertEquals('Cold',l.Rating);
        }
    }
    
    public static testMethod void testManyDoNotCall(){
        createTestData();
        
        List<Lead> leadsToUpdate = new List<Lead>();//Create a List to update our leads in bulk
        
        //Use a for loop to prepare our updates
        for(Lead l : leadsToInsert){
            for(String competitorName : competitorNames){
                l.Company = competitorName;
            }
            leadsToUpdate.add(l);
        }
        
        test.startTest();//Start our actual test, updating our records
        update leadsToUpdate;//issue update call
        test.stopTest();
        
        
        List<Lead> testLeads = [Select DoNotCall from Lead];//Query for Leads, getting the field updated by our Lead Trigger
        
        //Use a for loop to check each Lead
        for(Lead l : testLeads){
            System.assert(l.DoNotCall);
        }
    }
    
    public static testMethod void testBothRatingDoNotCall(){
        createTestData();
        
        List<Lead> leadsToUpdate = new List<Lead>();//Create a List to update our leads in bulk
        
        //Use a for loop to prepare our updates
        for(Lead l : leadsToInsert){
            for(String competitorName : competitorNames){
                l.Status = 'Closed - Not Converted';
                l.Company = competitorName;
                leadsToUpdate.add(l);
            }
        }
        
        test.startTest();//Start our actual test, updating our records
        update leadsToUpdate;//issue update call
        test.stopTest();
        
        
        List<Lead> testLeads = [Select Rating, DoNotCall from Lead];//Query for Leads, getting the field updated by our Lead Trigger
        
        //Use a for loop to check each Lead
        for(Lead l : testLeads){
            System.assertEquals('Cold', l.Rating);
            System.assert(l.DoNotCall);
        }
    }
}