Salesforce Future method in salesforce – @future

global class SomeClass {
    @future
    public static void someFutureMethod(List<Id> recordIds) {
      List<Account> accounts = [Select Id, Name from Account Where Id IN :recordIds];
      // process account records to do awesome stuff
    }
}  

public with sharing class ExampleFuture {
    public static void methodNoFuture(Set<Id> idsSet) {
        String sql = 'SELECT Id,Name FROM Opportunity where Id in :idsSet';
        List<Opportunity> opps = Database.query(sql);
        List<Opportunity> newOppList = new List<Opportunity>();
        for(Opportunity opp : opps) {
            opp.stageName = 'Closed Won';
            newOppList.add(opp);
        }
        update newOppList;
        System.debug('>>>>>>>>methodNoFuture::'+System.isQueueable());
    }

    @future
    public static void methodFuture(Set<Id> idsSet) {
        String sql = 'SELECT Id,Name FROM Opportunity where Id in :idsSet';
        List<Opportunity> opps = Database.query(sql);
        List<Opportunity> newOppList = new List<Opportunity>();
        for(Opportunity opp : opps) {
            opp.stageName = 'Closed Won';
            newOppList.add(opp);
        }
        update newOppList;
        System.debug('>>>>>>>>methodFuture::'+System.isQueueable());
    }
}

@isTest
public with sharing class ExampleFutureTest {
    static testMethod void FutureTest001() {
        List<Opportunity> oppList = new List<Opportunity>();
        for(integer i = 0; i<200; i++){
            Opportunity oppItem = new Opportunity(Name='methodNoFutureOpportunity'+ i,
                                StageName='Perception Analysis',
                                CloseDate = Date.Today(),
                                DeleteFlg__c = true);
            oppList.add(oppItem);
        }
        insert oppList;
        Map<Id, Opportunity> oppsMap = new Map<Id, Opportunity>(oppList);
        ExampleFuture.methodNoFuture(oppsMap.keySet());

        List<Opportunity> oppUpdateList = [SELECT Id,StageName FROM Opportunity WHERE DeleteFlg__c = true];
        System.assertEquals(200, oppUpdateList.size());
        if (oppUpdateList != null && oppUpdateList.size() >0) {
            for (Opportunity oppUpdate : oppUpdateList) {
                System.assertEquals('Closed Won', oppUpdate.StageName);
            }
        }
    }
    static testMethod void FutureTest002() {
        List<Opportunity> oppList = new List<Opportunity>();
        for(integer i = 0; i<200; i++){
            Opportunity oppItem = new Opportunity(Name='methodFutureOpportunity'+ i,
                                StageName='Perception Analysis',
                                CloseDate = Date.Today(),
                                DeleteFlg__c = true);
            oppList.add(oppItem);
        }
        insert oppList;
        Map<Id, Opportunity> oppsMap = new Map<Id, Opportunity>(oppList);

        Test.startTest();
        ExampleFuture.methodFuture(oppsMap.keySet());
        Test.stopTest();

        List<Opportunity> oppUpdateList = [SELECT Id,StageName FROM Opportunity WHERE DeleteFlg__c = true];
        System.assertEquals(200, oppUpdateList.size());
        if (oppUpdateList != null && oppUpdateList.size() >0) {
            for (Opportunity oppUpdate : oppUpdateList) {
                System.assertEquals('Closed Won', oppUpdate.StageName);
            }
        }
    }
}

public with sharing class ExampleMixedDMLFuture {
    public static void useFutureMethod() {
        // First DML operation
        Account a = new Account(Name='Acme');
        insert a;
        System.debug('>>>>>>>>useFutureMethod11::'+System.isQueueable());
        // This next operation (insert a user with a role)
        // can't be mixed with the previous insert unless
        // it is within a future method.
        // Call future method to insert a user with a role.
        ExampleInsertUserFuture.insertUserWithRole(
            'xiang@awcomputing.com', 'xiang',
            'yu@awcomputing.com', 'yu');
        System.debug('>>>>>>>>useFutureMethod22::'+System.isQueueable());
    }
}

public with sharing class ExampleInsertUserFuture {
    @future
    public static void insertUserWithRole(String uname, String al, String em, String lname) {
        System.debug('>>>>>>>>insertUserWithRole111::'+System.isQueueable());
        Profile p = [SELECT Id FROM Profile WHERE Name='Standard User'];
        UserRole r = [SELECT Id FROM UserRole WHERE Name='COO'];
        // Create new user with a non-null user role ID
        User u = new User(alias = al, email=em,
            emailencodingkey='UTF-8', lastname=lname,
            languagelocalekey='en_US',
            localesidkey='en_US', profileid = p.Id, userroleid = r.Id,
            timezonesidkey='America/Los_Angeles',
            username=uname);
        insert u;
        System.debug('>>>>>>>>insertUserWithRole222::'+System.isQueueable());
    }
}

@isTest
public with sharing class ExampleMixedDMLFutureTest {
    @isTest static void test1() {
        User thisUser = [SELECT Id FROM User WHERE Id = :UserInfo.getUserId()];
       // System.runAs() allows mixed DML operations in test context
        System.runAs(thisUser) {
            // startTest/stopTest block to run future method synchronously
            Test.startTest();
            ExampleMixedDMLFuture.useFutureMethod();
            Test.stopTest();
        }
        // The future method will run after Test.stopTest();

        // Verify account is inserted
        Account[] accts = [SELECT Id from Account WHERE Name='Acme'];
        System.assertEquals(1, accts.size());
        // Verify user is inserted
        User[] users = [SELECT Id from User where username='xiang@awcomputing.com'];
        System.assertEquals(1, users.size());
    }
}