Any one pls remove this error from test class
System.NullPointerException: Argument cannot be null.
Class.Leadpage.<init>: line 19, column 1
Class.Leadtestsss.runTest1: line 31, column 1

TEST Class

@isTest
public class Leadtestss{  
    static testMethod void runTest1() {
    Account account = new Account();
       account.Name = 'Acc3';
       insert account;         

       Contact contact = new Contact();
       contact.FirstName = 'Todda';
       contact.LastName = 'Wilmss';
       contact.AccountID = account.Id;
       contact.Email = 'twilms@verisign.conm';
       contact.MobilePhone = '918527116723';
       insert contact; 
              
       Lead lead = new Lead();
       lead.FirstName = 'test';
       lead.LastName = 'foo'; 
       lead.company='Acc3';      
       insert lead; 
            
        test.startTest();
        PageReference pageRef = Page.Leadpage;
        pageRef.getParameters().put('Id', String.valueOf(lead.Id));
        Test.setCurrentPage(pageRef);
        Test.setMock(HttpCalloutMock.class, new Leadpagemock());
        ApexPages.StandardController sc1 = new ApexPages.StandardController(Lead);//Instance of your object
        Leadpage testDObj = new Leadpage();
        testDObj.getperformcallout();
        test.stopTest();  
            
    }    
}

 

Page MOCK Class

@IsTest(seeAllData = false)
global class Leadpagemock implements HttpCalloutMock 
{    
    global HTTPResponse respond(HTTPRequest req) {        
        HttpResponse res = new HttpResponse();
        res.setHeader('Content-Type', 'application/json');
        res.setBody('[{"foo":"bar"}]');
        res.setStatusCode(200);        
        return res;
    }   
}

 

Main Class

public class Leadpage{
    public Leadpage(ApexPages.StandardController controller) {
    }    
    public  Leadpage()
        {}        
     public   String MySessionID = UserInfo.getSessionID();
     public   String conId = ApexPages.currentPage().getParameters().get('Id');
     public   String EmailCon=[Select email from Lead where Id=:conId ].email;
     public   String myurl= URL.getSalesforceBaseUrl().toExternalForm() + '/services/Soap/c/10.0/' + UserInfo.getOrganizationId();    
     public   string c='eU9WzoFgU4n8Apu5PYxcNGRZswRDZJWDEMdbQVU85gw=';
     public   String Acode='00530000000rLMxAAM';
     public   String Oid = UserInfo.getOrganizationId();  
    Blob cryptoKey= EncodingUtil.base64Decode(c);
    Blob data = Blob.valueOf(MySessionID );
    Blob data1 = Blob.valueOf(myurl);
    Blob data2 = Blob.valueOf(conId);
    Blob data3 = Blob.valueOf(EmailCon);
    Blob data4 = Blob.valueOf(Acode);
    Blob data5 = Blob.valueOf(Oid);   
    Blob encryptedData = Crypto.encryptWithManagedIV('AES256', cryptoKey, data);
    Blob encryptedData1 = Crypto.encryptWithManagedIV('AES256', cryptoKey, data1);
    Blob encryptedData2 = Crypto.encryptWithManagedIV('AES256', cryptoKey, data2);
    Blob encryptedData3 = Crypto.encryptWithManagedIV('AES256', cryptoKey, data3 );
    Blob encryptedData4 = Crypto.encryptWithManagedIV('AES256', cryptoKey, data4 );
    Blob encryptedData5 = Crypto.encryptWithManagedIV('AES256', cryptoKey, data5 );  
    public    String b64Data = EncodingUtil.base64Encode(encryptedData);
    public    String b64Data1 = EncodingUtil.base64Encode(encryptedData1);
    public    String b64Data2 = EncodingUtil.base64Encode(encryptedData2);
    public    String b64Data3 = EncodingUtil.base64Encode(encryptedData3);
    public    String b64Data4 = EncodingUtil.base64Encode(encryptedData4);
    public    String b64Data5 = EncodingUtil.base64Encode(encryptedData5);
    String testurl='sessionID='+EncodingUtil.urlEncode(b64Data, 'UTF-8')+'&serverUrl='+EncodingUtil.urlEncode(b64Data1, 'UTF-8')+'&contactID='+EncodingUtil.urlEncode(b64Data2, 'UTF-8')+'&email='+EncodingUtil.urlEncode(b64Data3, 'UTF-8');   
    public String email = EncodingUtil.urlEncode(b64Data3, 'UTF-8');    
    public String aucode= EncodingUtil.urlEncode(b64Data4, 'UTF-8');
    public String ocode= EncodingUtil.urlEncode (b64Data5,  'UTF-8');
  
    public List<LeadVideoViewAllWrap> ConsoleWrapperList{get;set;}
    public List<LeadVideoViewAllWrap> getperformcallout(){
        ConsoleWrapperList = new List<LeadVideoViewAllWrap>();
        HttpRequest req = new HttpRequest();
        HttpResponse res = new HttpResponse();
        Http http = new Http();
        string url = 'https://www.demomail.net/sf/api/LeadVideoViewAllController?AUCode='+aucode+'&SOrgID='+ocode+'&Email='+email+'&session='+testurl;
        req.setEndpoint(url);
        req.setMethod('GET');        
        res = http.send(req);
        if(res.getstatusCode() == 200 && res.getbody() != null){
            ConsoleWrapperList=(List<LeadVideoViewAllWrap>)json.deserialize(res.getbody(),List<LeadVideoViewAllWrap>.class); 
        }
        return consolewrapperlist;
    }  
}