//Send email with Multiple attachments, and before sending edit template
public class SendEmail {

    public Account acc;
    public String body { get; set; }    
    Product_EmailTemplates__c template;//Custom settings to read the template, which template to send
    public Opportunity opp { get; set;}
    public String subject { get; set; }
    public String htmlBody {get; set;}
    

    // Create a constructor that populates the Opportunity object
    public SendEmail(ApexPages.StandardController controller) {        
        opp = [Select Id, Name, Email__c, Amount, Contact_Name__c, Account.PersonContactId, Account.id, Product__r.Name, Account.Name, StageName, Tax_Amount__c, Total_after_Tax__c, 
               payment_1_Amount__c, Payment_2_Amount__c, Payment_3_Amount__c, Payment_1_Before_Tax__c, Payment_2_Before_Tax__c, Payment_3_Before_Tax__c, Payment_1_Tax_Amount__c, 
               Payment_2_Tax_Amount__c, Payment_3_Tax_Amount__c, Potential_Number__c,Branch_Name__c, Branch_Name__r.Name, Branch_Name__r.Address_1__c, Branch_Name__r.Address_2__c, Branch_Name__r.City__c, 
               Branch_Name__r.Country__c, Branch_Name__r.Main_Phone_1__c, Branch_Name__r.Main_Phone_2__c, Branch_Name__r.Main_Phone_3__c, Branch_Name__r.Region__c, Branch_Name__r.State__c, 
               Branch_Name__r.Zip_Postal_Code__c, Product__r.Product_Type__c, Admin_Fee__c, Payment_1_plus_Admin_Fee__c
                    from Opportunity where Id = :ApexPages.currentPage().getParameters().get('id')];
              
        EmailTemplate emailTemplate = [SELECT Id, Subject, HtmlValue, Body FROM EmailTemplate WHERE Id = :getTemplateId(opp.Product__r.Name, opp.Product__r.Product_Type__c)];
    
        htmlBody = emailTemplate.HtmlValue;
        subject = emailTemplate.subject;
    }
    
    //Send the email with two attachments
    public PageReference send() {
        // Define the email
        Messaging.SingleEmailMessage email = new Messaging.SingleEmailMessage(); 
        
        //Send email if Branch not equals to Saudi Arabia and Product type is Standard
        if(opp.Branch_Name__r.Name != 'Saudi Arabia' && opp.Product__r.Product_Type__c == 'Standard'){
            // Reference the attachment page and pass in the Opportunity ID
            PageReference pdf1 =  Page.CCLPdf;//CCLPdf is a Visualforce page
            pdf1.getParameters().put('id',opp.id); 
            pdf1.setRedirect(true);
    
            // Take the PDF content
            Blob b1 = pdf1.getContentAsPDF();
            
            PageReference pdf2 =  Page.ProformaInvoicePdf;//ProformaInvoicePdf is a Visualforce page
            pdf2.getParameters().put('id',opp.id); 
            pdf2.setRedirect(true);
    
            // Take the PDF content
            Blob b2 = pdf2.getContentAsPDF();
    
            // Create the email attachment
            Messaging.EmailFileAttachment efa1 = new Messaging.EmailFileAttachment();
            efa1.setFileName(opp.account.Name+'-CCL.pdf');//set the email attachment name
            efa1.setBody(b1);
            
            Messaging.EmailFileAttachment efa2 = new Messaging.EmailFileAttachment();
            efa2.setFileName(opp.account.Name+'-Invoice.pdf');//set the email attachment name
            efa2.setBody(b2);
            
            // Sets the paramaters of the email
            email.setSubject(subject);//Auto populate the Subject from Template
            email.setHtmlBody(htmlBody);//Auto populate the Body from Template
            //email.setTemplateId('00Xj0000000Yg9k');//getTemplateId(opp.Product__r.Name)
            email.setTargetObjectId(opp.Account.PersonContactId);
            email.setSaveAsActivity(true);
            email.setFileAttachments(new Messaging.EmailFileAttachment[] {efa1,efa2});
            StoringAttachments();
        }
        
        //Send email if Branch not equals to Saudi Arabia and Product type is Canada
        if(opp.Branch_Name__r.Name != 'Saudi Arabia' && opp.Product__r.Product_Type__c == 'Canada'){
            // Reference the attachment page and pass in the Opportunity ID
            PageReference pdf3 =  Page.CANCCLPdf;//CANCCLPdf is a Visualforce page
            pdf3.getParameters().put('id',opp.id); 
            pdf3.setRedirect(true);
    
            // Take the PDF content
            Blob b3 = pdf3.getContentAsPDF();
            
            PageReference pdf4 =  Page.ProformaInvoicePdf;//ProformaInvoicePdf is a Visualforce page
            pdf4.getParameters().put('id',opp.id); 
            pdf4.setRedirect(true);
    
            // Take the PDF content
            Blob b4 = pdf4.getContentAsPDF();
    
            // Create the email attachment
            Messaging.EmailFileAttachment efa3 = new Messaging.EmailFileAttachment();
            efa3.setFileName(opp.account.Name+'-CANCCL.pdf');//set the email attachment name
            efa3.setBody(b3);
            
            Messaging.EmailFileAttachment efa4 = new Messaging.EmailFileAttachment();
            efa4.setFileName(opp.account.Name+'-CANInvoice.pdf');//set the email attachment name
            efa4.setBody(b4);
            
            // Sets the paramaters of the email
            email.setSubject(subject);//Auto populate the Subject from Template
            email.setHtmlBody(htmlBody);//Auto populate the Body from Template
            //email.setTemplateId('00Xj0000000Yg9k');//getTemplateId(opp.Product__r.Name)
            email.setTargetObjectId(opp.Account.PersonContactId);
            email.setSaveAsActivity(true);
            email.setFileAttachments(new Messaging.EmailFileAttachment[] {efa3,efa4});
            StoringAttachments();
        }
        
        //Send email if Branch is saudi Arabia and Product type is Standard
        if(opp.Branch_Name__r.Name == 'Saudi Arabia' && opp.Product__r.Product_Type__c == 'Standard'){
            // Reference the attachment page and pass in the Opportunity ID
            PageReference pdf5 =  Page.KSACCLPdf;//KSACCLPdf is a Visualforce page
            pdf5.getParameters().put('id',opp.id); 
            pdf5.setRedirect(true);
    
            // Take the PDF content
            Blob b5 = pdf5.getContentAsPDF();
            
            PageReference pdf6 =  Page.ProformaInvoicePdf;//ProformaInvoicePdf is a Visualforce page
            pdf6.getParameters().put('id',opp.id); 
            pdf6.setRedirect(true);
    
            // Take the PDF content
            Blob b6 = pdf6.getContentAsPDF();
    
            // Create the email attachment
            Messaging.EmailFileAttachment efa5 = new Messaging.EmailFileAttachment();
            efa5.setFileName(opp.account.Name+'-KSACCL.pdf');//set the email attachment name
            efa5.setBody(b5);
            
            Messaging.EmailFileAttachment efa6 = new Messaging.EmailFileAttachment();
            efa6.setFileName(opp.account.Name+'-KSAInvoice.pdf');//set the email attachment name
            efa6.setBody(b6);
            
            // Sets the paramaters of the email
            email.setSubject(subject);//Auto populate the Subject from Template
            email.setHtmlBody(htmlBody);//Auto populate the Body from Template
            //email.setTemplateId('00Xj0000000Yg9k');//getTemplateId(opp.Product__r.Name)
            email.setTargetObjectId(opp.Account.PersonContactId);
            email.setSaveAsActivity(true);
            email.setFileAttachments(new Messaging.EmailFileAttachment[] {efa5,efa6});
            StoringAttachments();
         } 
         
         //Send email if Branch is saudi Arabia and Product type is Canada
         if(opp.Branch_Name__r.Name == 'Saudi Arabia' && opp.Product__r.Product_Type__c == 'Canada'){
            // Reference the attachment page and pass in the Opportunity ID
            PageReference pdf7 =  Page.KSACANCCLPdf;//KSACANCCLPdf is a Visualforce page
            pdf7.getParameters().put('id',opp.id); 
            pdf7.setRedirect(true);
    
            // Take the PDF content
            Blob b7 = pdf7.getContentAsPDF();
            
            PageReference pdf8 =  Page.ProformaInvoicePdf;//ProformaInvoicePdf is a Visualforce page
            pdf8.getParameters().put('id',opp.id); 
            pdf8.setRedirect(true);
    
            // Take the PDF content
            Blob b8 = pdf8.getContentAsPDF();
    
            // Create the email attachment
            Messaging.EmailFileAttachment efa7 = new Messaging.EmailFileAttachment();
            efa7.setFileName(opp.account.Name+'-KSACANCCL.pdf');//set the email attachment name
            efa7.setBody(b7);
            
            Messaging.EmailFileAttachment efa8 = new Messaging.EmailFileAttachment();
            efa8.setFileName(opp.account.Name+'-KSACANInvoice.pdf');//set the email attachment name
            efa8.setBody(b8);
            
            // Sets the paramaters of the email
            email.setSubject(subject);//Auto populate the Subject from Template
            email.setHtmlBody(htmlBody);//Auto populate the Body from Template
            //email.setTemplateId('00Xj0000000Yg9k');//getTemplateId(opp.Product__r.Name)
            email.setTargetObjectId(opp.Account.PersonContactId);
            email.setSaveAsActivity(true);
            email.setFileAttachments(new Messaging.EmailFileAttachment[] {efa7,efa8});
            StoringAttachments();
         } 
    
            // Sends the email
            Messaging.SendEmailResult [] r = 
                Messaging.sendEmail(new Messaging.SingleEmailMessage[] {email}); 
        
        
        return new PageReference('/'+opp.Id);
    }
    
    //Creating attachments
    public void StoringAttachments() {
        //Send attachments if Branch is India and Product type is Standard
        if((opp.Branch_Name__r.Name == 'India' || opp.Branch_Name__r.Name == 'United Kingdom') && opp.Product__r.Product_Type__c == 'Standard'){
            Attachment myAttach1 = new Attachment();
            myAttach1.ParentId = opp.Account.PersonContactId;
            myAttach1.name = opp.account.Name+'-CCL.pdf';
            PageReference myPdf1 = Page.CCLPdf;
            myAttach1.body = myPdf1.getContentAsPdf();
            insert myAttach1;
            
            Attachment myAttach2 = new Attachment();
            myAttach2.ParentId = opp.Account.PersonContactId;
            myAttach2.name = opp.account.Name+'-Invoice.pdf';
            PageReference myPdf2 = Page.ProformaInvoicePdf;
            myAttach2.body = myPdf2.getContentAsPdf();
            insert myAttach2;
        }
        
        //Send attachments if Branch is India and Product type is Canada
        if((opp.Branch_Name__r.Name == 'India' || opp.Branch_Name__r.Name == 'United Kingdom') && opp.Product__r.Product_Type__c == 'Canada'){
            Attachment myAttach3 = new Attachment();
            myAttach3.ParentId = opp.Account.PersonContactId;
            myAttach3.name = opp.account.Name+'-CANCCL.pdf';
            PageReference myPdf3 = Page.CANCCLPdf;
            myAttach3.body = myPdf3.getContentAsPdf();
            insert myAttach3;
            
            Attachment myAttach4 = new Attachment();
            myAttach4.ParentId = opp.Account.PersonContactId;
            myAttach4.name = opp.account.Name+'-CANInvoice.pdf';
            PageReference myPdf4 = Page.ProformaInvoicePdf;
            myAttach4.body = myPdf4.getContentAsPdf();
            insert myAttach4;
        }
        
        //Send attachments if Branch is saudi Arabia and Product type is Standard
        if(opp.Branch_Name__r.Name == 'Saudi Arabia' && opp.Product__r.Product_Type__c == 'Standard'){
            Attachment myAttach5 = new Attachment();
            myAttach5.ParentId = opp.Account.PersonContactId;
            myAttach5.name = opp.account.Name+'-KSACCL.pdf';
            PageReference myPdf5 = Page.KSACCLPdf;
            myAttach5.body = myPdf5.getContentAsPdf();
            insert myAttach5;
            
            Attachment myAttach6 = new Attachment();
            myAttach6.ParentId = opp.Account.PersonContactId;
            myAttach6.name = opp.account.Name+'-KSAInvoice.pdf';
            PageReference myPdf6 = Page.ProformaInvoicePdf;
            myAttach6.body = myPdf6.getContentAsPdf();
            insert myAttach6;
        }
        
        //Send attachments if Branch is saudi Arabia and Product type is Canada
        if(opp.Branch_Name__r.Name == 'Saudi Arabia' && opp.Product__r.Product_Type__c == 'Canada'){
            Attachment myAttach7 = new Attachment();
            myAttach7.ParentId = opp.Account.PersonContactId;
            myAttach7.name = opp.account.Name+'-KSACANCCL.pdf';
            PageReference myPdf7 = Page.KSACANCCLPdf;
            myAttach7.body = myPdf7.getContentAsPdf();
            insert myAttach7;
            
            Attachment myAttach8 = new Attachment();
            myAttach8.ParentId = opp.Account.PersonContactId;
            myAttach8.name = opp.account.Name+'-KSACANInvoice.pdf';
            PageReference myPdf8 = Page.ProformaInvoicePdf;
            myAttach8.body = myPdf8.getContentAsPdf();
            insert myAttach8;
        }
    } 
    
    //Reads the Template from Custom settings        
    public String getTemplateId(String prodName, String prodType){
       template = [Select Name, Email_Template_Id__c, Product_Type__c from Product_EmailTemplates__c 
                        where Name = : prodName and Product_Type__c = : prodType];
       return template.Email_Template_Id__c;
   }

}

Test Class:

@isTest(seeAllData=true)
public class CreateCaseTests{

     private static Id leadId;

static testMethod void testCreateCase() {
    
        
        //Inserting Products
        Product2 prod = new Product2();
        prod.Name = 'Resident Visa';
        prod.ProductCode = 'RV';
        insert prod;
        
        //Inserting Products
        Product2 prod1 = new Product2();
        prod1.Name = 'Permanant Visa';
        prod1.ProductCode = 'PV';
        insert prod1;
        
        //get standard pricebook
        Pricebook2  standardPb = [select Id, Name, isActive from Pricebook2 where IsStandard = true limit 1];
        
        //Inserting pricebook
        Pricebook2 pb = new Pricebook2();
        pb.Name = 'India';
        pb.IsActive= true;
        insert pb;
        
        //Inserting pricebook
        Pricebook2 pb1 = new Pricebook2();
        pb1.Name = 'Saudi Arabia';
        pb1.IsActive= true;
        insert pb1;
        
        //Inserting pricebookEntry
        PricebookEntry pbe = new PricebookEntry();
        pbe.Pricebook2Id = standardPb.Id;
        pbe.Product2Id = prod.Id;
        pbe.UnitPrice = 1.0;
        //pbe.UseStandardPrice = true;
        pbe.IsActive = true;
        insert pbe;
        
        //Inserting pricebookEntry
        PricebookEntry pbe1 = new PricebookEntry();
        pbe1.Pricebook2Id = standardPb.Id;
        pbe1.Product2Id = prod1.Id;
        pbe1.UnitPrice = 1.0;
        //pbe.UseStandardPrice = true;
        pbe1.IsActive = true;
        insert pbe1;
        
        Lead testLead = new Lead();
            testLead.FirstName = 'Test First';
            testLead.LastName = 'Test Last';
            //testLead.Company = 'Test Co';
            //testLead.RecordTypeId = '012110000004b9Q';
            testLead.Status = 'Converted';
            testLead.LeadSource = 'Web';
            testLead.Date_Received__c = System.Today();
            testLead.Email = 'ranjith@rixyncs.co.in';
            testLead.Payment_Plan__c = '2 Monthly Payments';
            testLead.Phone = '+919590854842';
            testLead.MobilePhone = '+919590854842';
            //testLead.Branch__c = 'India';
            testLead.CurrencyIsoCode = 'INR';
            testLead.Destination_Visa__c = 'Denmark';
            testLead.Product__c = prod.Id;
            testLead.Date_of_Birth__c = System.Today();
            testLead.Age__c = 30;
            testLead.Occupation__c = 'SE';
            testLead.Number_of_years_in_this_occupation__c = 2;
            testLead.Highest_Qualification__c = 'MCA';
            testLead.Experience__c = 'Full - Time';
            testLead.Dependents__c = '2';
            testLead.Nationality_Immigration_Status__c = 'Pending';
            testLead.Criminal_Health__c = 'No';
            testLead.Job_Offer__c = True;
            testLead.Maintenance__c = 'Yes';
            testLead.Family_Links__c = True;
            testLead.Country = 'India';
            testLead.Country__c = 'India';
            insert testLead;
            leadId = testLead.Id;
            
            System.currentPagereference().getParameters().put('id',testLead.id);

        
        
        
        Database.LeadConvert lc = new database.LeadConvert();
        lc.setLeadId(leadId);
        //lc.setAccountId(myRecordType.Id) ;
        //lc.strAccountId= '1';
        //lc.strContactId= '1';
        LeadStatus convertStatus = [Select Id, MasterLabel from LeadStatus where IsConverted=true limit 1];
        lc.setConvertedStatus(convertStatus.MasterLabel);
        
        Database.LeadConvertResult lcr = Database.convertLead(lc);
        //lcr.getAccountId();
        //lcr.getContactId();
        //lcr.getOpportunityId();
        
        //this line returned my lead with isConverted:true and ids for related contact and account
    /*Lead leadFromDB = [select 
                       FirstName,
                       LastName,
                       Country,
                       isConverted,
                       ConvertedAccountId,
                       ConvertedContactId
                       from Lead where id = : testLead.Id];
    System.debug('this lead looks like: ' + leadFromDB);

    // successfully queried contact, would produce query exception if no contact found
    Contact c = [select Id,FirstName,LastName from Contact where Id = : leadFromDB.ConvertedContactId];

    // again success, no query exception
    Account a = [select Id,Name from Account where Id = : leadFromDB.ConvertedAccountId];

    // confirmation in my log of what I got back.
    System.debug(c);
    System.debug(a);*/

    //System.assert(lcr.isSuccess()); //<--assert passed   
        
        System.assert(lcr.isSuccess());
        

    
        /*Inserting Lead and converting
        Lead ld = new Lead();
        ld.LastName='Doe';
        ld.FirstName='John';
        ld.Company='Test';
        ld.Status = 'Converted';
        ld.LeadSource = 'Web';
        ld.Date_Received__c = System.Today();
        ld.Email = 'ranjith@rixyncs.co.in';
        ld.Payment_Plan__c = '2 Monthly Payments';
        ld.Phone = '+919590854842';
        ld.MobilePhone = '+919590854842';
        ld.Branch__c = 'India';
        ld.CurrencyIsoCode = 'INR';
        ld.Destination_Visa__c = 'Denmark';
        ld.Product__c = prod.Id;
        ld.Date_of_Birth__c = System.Today();
        ld.Age__c = 30;
        ld.Occupation__c = 'SE';
        ld.Number_of_years_in_this_occupation__c = 2;
        ld.Highest_Qualification__c = 'MCA';
        ld.Experience__c = 'Full - Time';
        ld.Dependents__c = '2';
        ld.Nationality_Immigration_Status__c = 'Pending';
        ld.Criminal_Health__c = 'No';
        ld.Job_Offer__c = True;
        ld.Maintenance__c = 'Yes';
        ld.Family_Links__c = True;
        insert ld;            


        ld =  [SELECT Id,Status, FirstName,LastName,Company,LeadSource
             FROM Lead
             WHERE Id = :ld.Id];

        System.assertEquals('Converted', ld.Status);*/
        
        RecordType myRecordType = [select id from RecordType where SobjectType='Account' AND IsPersonType=True limit 1];
    
        //Inserting Account
        Account acc = new Account();
        acc.LastName = 'Ranjith';
        acc.RecordTypeId = myRecordType.Id;
        insert acc;
        
        //Inserting Contact
        Contact con = new Contact();
        con.LastName = 'kumar';
        //con.AccountId = acc.Id;
        insert con;    
              
                
        
        
        //Inserting Potential
        Opportunity opp = new Opportunity();
        opp.Name = 'Ranjith kumar';
        //opp.Potential_Number__c = '0011';
        opp.AccountId = acc.Id;
        opp.CloseDate = System.today()+20;
        opp.StageName = 'CCL Sent';
        opp.Contact_Name__c = con.Id;
        opp.Type  = 'Existing Business';
        opp.English_Language__c  = 'Vocational';
        opp.Payment_Plan__c = '2 Monthly Payments';
        opp.Tax_Amount__c = 1000.00;
        opp.Total_after_Tax__c = 1000000.00;
        opp.Amount = 10000000.00;
        opp.Date_of_Birth__c = System.today();
        opp.Destination_Visa__c = 'US';
        opp.TimeFrame__c = '3 Months';
        opp.Eligibility_Score__c = 60;
        //opp.Branch__c = 'India';
        opp.Occupation__c = 'SE';
        opp.Number_of_years_in_this_occupation__c = 2;
        opp.Highest_Qualification__c = 'MCA';
        opp.Experience__c = 'Full - Time';
        opp.Dependents__c = '2';
        opp.Nationality_Immigration_Status__c = 'Pending';
        opp.Criminal_Health__c = 'No';
        opp.Job_Offer__c = True;
        opp.Maintenance__c = 'Yes';
        opp.Family_Links__c = True;
        opp.payment_1_Amount__c = 100.00;
        opp.Payment_2_Amount__c = 100.00;
        opp.Payment_3_Amount__c = 100.00;
        opp.Payment_1_Received_Date__c = System.today();
        opp.Payment_2_Due_Date__c = System.today()+30;
        opp.Payment_3_Due_Date__c = System.today()+60;
        opp.Payment_1_Before_Tax__c = 100.00;
        opp.Payment_2_Before_Tax__c = 100.00;
        opp.Payment_3_Before_Tax__c = 100.00;
        opp.Payment_1_Status__c = 'Received';
        opp.Payment_2_Status__c = 'Pending';
        opp.Payment_3_Status__c = 'Pending';   
        opp.Pricebook2Id  = pbe.Pricebook2Id; 
        opp.Product__c = prod.Id;
        insert opp;
    System.currentPagereference().getParameters().put('id',opp.id);
         Blob content;        
         PageReference pf = page.CCLPdf;
         Attachment objAtt = new Attachment();
         objAtt.Name = opp.Account.Name + '-CCL.Pdf';
         objAtt.body =  Blob.valueof('string');
         objAtt.ParentId = opp.Id;        
         if (Test.IsRunningTest()){
                content=Blob.valueOf('UNIT.TEST');
             }else{
                content=pf.getContent();
             }
         insert objAtt;
        
ApexPages.StandardController stdController = new ApexPages.StandardController(opp); 
        SendEmail send = new SendEmail(stdController);
        
        send.send();
        send.StoringAttachments();
        send.getTemplateId('Permanant Visa','Standard');
        
    
      }
    
}