Best practice is to always stage your data in a Test Method - and to never statically declare variables within a Method.

If you did something like this:

public class ABC {

    public User usr = [SELECT Use_Policy__c from User where Id=:UserInfo.getUserId() and IsActive=true];

    public PageReference callfun() {
        Boolean flag= false;
             
	// REMOVE THE LINE THAT CREATES THE USR OBJECT FROM HERE
        system.debug('aaaaaaaaaaaaaaa'+usr);

        if(usr.Use_Policy__c) {
            PageReference pageRef = Page.UsePolicySuccess;
            pageRef.setRedirect(true);
            return pageRef;
        } else{
        
           PageReference pageRef = Page.UsePolicyPage;
           pageRef.setRedirect(true);
           return pageRef;       
        }
    }
    
    public static testMethod void testMethod1()
     {
        
	// Instanciate Object 
	ABC abcobj=new ABC();

	test.startTest();

	// Prep Variables
	Profile p = [select id from profile where name='Standard User'];


	// Stage Data for Positive Path
	User uPos = new User(alias = 'standt', email='standarduser@testorg.com',
			emailencodingkey='UTF-8', lastname='Testing', languagelocalekey='en_US',
			localesidkey='en_US', profileid = p.Id,timezonesidkey='America/Los_Angeles', 
			username='standarduser@testorg.com', Use_Policy__c = true);
	insert uPos;

	// Positive Path TEST
	abcobj.usr = uPos;
        abcobj.callfun();

	// Stage Data for Negative Path
	User uNeg = new User(alias = 'standt2', email='standarduser2@testorg.com',
			emailencodingkey='UTF-8', lastname='Testing2', languagelocalekey='en_US',
			localesidkey='en_US', profileid = p.Id,timezonesidkey='America/Los_Angeles', 
			username='standarduser2@testorg.com', Use_Policy__c = false);
	insert uNeg;
	
	// Negative Path TEST
	abcobj.usr = uNeg;
        abcobj.callfun();

	test.stopTest();

    }

}