I have write this class in Salesforce but not able write test class. Please anybody can help me to write test class.

public without sharing class CustomizedReportController{
    public String selectedReportID {get;set;}
    public String additionalEmails {get;set;}
    public Contact reportWrapper {get;set;}
    
    public String bgColor {public get; public set;}
    public String borderColor {public get; public set;}
    public String fontColor {public get; public set;}
    public String colHeaderColor {public get; public set;}
    public String styleBackgroundTemplate { public get; public set; }
    
    public boolean editStyle {get;set;}
    
    private Map<String, String> mapReports;
      
    public CustomizedReportController() {
      additionalEmails = '';
        mapReports = new Map<String, String>();
        reportWrapper = new Contact();
        if(ApexPages.currentPage().getParameters().containsKey('reportId')){
            selectedReportID = ApexPages.currentPage().getParameters().get('reportId');            
        }
        editStyle = false;
        initDefaultTheme();
        updateReportWrapper();        
        styleBackgroundTemplate = 'background: #START_COLOR;';
        styleBackgroundTemplate += 'background: -moz-linear-gradient(top, #START_COLOR 0%, #END_COLOR 100%);';
        styleBackgroundTemplate += 'background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,#START_COLOR), color-stop(100%,#END_COLOR));';
        styleBackgroundTemplate += 'background: -webkit-linear-gradient(top, #START_COLOR 0%,#END_COLOR 100%);';
        styleBackgroundTemplate += 'background: -o-linear-gradient(top, #START_COLOR 0%,#END_COLOR 100%);';
        styleBackgroundTemplate += 'background: -ms-linear-gradient(top, #START_COLOR 0%,#END_COLOR 100%);';
        styleBackgroundTemplate += 'filter: progid:DXImageTransform.Microsoft.gradient(startColorStr=\'#START_COLOR\', EndColorStr=\'#END_COLOR\');';
    }
    
    private void initDefaultTheme(){
        bgColor = 'FFFFFF';
        borderColor = '000000';
        fontColor = '000000';
        colHeaderColor = '000000';        
    }
    
    public PageReference updateEditStyle(){
      editStyle = true;
      return null;
    }
       
    public List<SelectOption> getAllReports() {
      List<SelectOption> lstOption = new List<SelectOption>();
      lstOption.add(new SelectOption('','----None----'));
      for(Report report :  [SELECT Id,Name FROM Report WHERE Format='Tabular' Order By Name Limit 100]) {
        lstOption.add(new SelectOption(String.valueOf(report.Id).substring(0,15),report.Name));
        mapReports.put(String.valueOf(report.Id).substring(0,15),report.Name);
      }
      return lstOption;  
    }
    
    public pageReference updateReportWrapper(){
      if(selectedReportID != null && selectedReportID != ''){
      
        List<Contact> lstreportWrap = new List<Contact>([SELECT Id, Name, email, 
        FirstName, LastName,MobilePhone,Phone,Level__c,Title
        FROM Contact WHERE Id = :selectedReportID]);
        
        if(lstreportWrap.size() > 0){
          reportWrapper = lstreportWrap[0];
          bgColor = lstreportWrap[0].Background_Color__c;
          borderColor = lstreportWrap[0].Border_color__c;
          fontColor = lstreportWrap[0].Font_Color__c;
          colHeaderColor = lstreportWrap[0].Column_Header_Color__c;
        }
        else{
          reportWrapper = new Contact ();          
        }
        if(reportWrapper != null){
          if(reportWrapper.Report_Header__c == null){
            //reportWrapper.Report_Header__c = mapReports.get(selectedReportID);
          }
          if(reportWrapper.Report_Title__c == null){
            reportWrapper.Report_Title__c = '<span style="font-weight:bold;font-size:22px;">'+mapReports.get(selectedReportID)+'</span>';
          }
          if(reportWrapper.Report_Footer__c == null){
            reportWrapper.Report_Footer__c = mapReports.get(selectedReportID);
          } 
        }
      }
      else{      
        reportWrapper = new Contact ();
      }
      return null;
    }
    
    public PageReference saveData(){
     if(selectedReportID != null && selectedReportID.trim() != ''){
       reportWrapper.FirstName = bgColor;
       reportWrapper.LastName = borderColor;       
       reportWrapper.Font_Color__c = fontColor;
       reportWrapper.Column_Header_Color__c = colHeaderColor;
       reportWrapper.Report_Id__c = selectedReportID.subString(0,15);     
       upsert reportWrapper;
                    
     }
     return null;     
    }
    
    public void cancel(){
      editStyle = false;
    }
     
  public PageReference sendEmail(){
  
    PageReference pgRef = Page.ContactTestPage;    
    pgRef.getParameters().put('reportId', selectedReportID);
    pgRef.setRedirect(true);
    Blob pdfval = pgRef.getContentAsPdf();
    
    Messaging.EmailFileAttachment attch = new Messaging.EmailFileAttachment();
    attch.setBody(pdfval);
    attch.setFileName('ReportPdf.pdf');
    // Send an email to the Apex job's submitter notifying of job completion.
    Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();
    List<String> emailAddresses = getEmailAddresses();

    mail.setToAddresses(emailAddresses);
    mail.setSubject('Report Results');
    mail.setPlainTextBody('Report Pdf');
    mail.setSaveAsActivity(false);
    mail.setFileAttachments(new List<Messaging.EmailFileAttachment>{attch});
    
    Messaging.sendEmail(new Messaging.SingleEmailMessage[] { mail });
    saveData();
    return null;
  }
  
  public List<String> getEmailAddresses(){
    
    List<String> emailAddresses = new List<String>();
    if(reportWrapper.Id != null){
      for(Contact con : [SELECT Email FROM Contact WHERE Id = :reportWrapper.Id]){
        if(con.Email != null){
          emailAddresses.add(con.Email);
        }
      }
    }
    if(reportWrapper.Id != null){
      for(Lead ld : [SELECT Email FROM Lead WHERE Id = :reportWrapper.Id]){
        if(ld.Email != null){
          emailAddresses.add(ld.Email);
        }
      }
    }
    if(reportWrapper.Id != null){
      for(User usr : [SELECT Email FROM User WHERE Id = :reportWrapper.Id]){
        if(usr.Email != null){
          emailAddresses.add(usr.Email);
        }
      }
    }
    if(!String.IsBlank(additionalEmails)){
      for(String str : additionalEmails.split(',')){
        emailAddresses.add(str.trim());        
      }
    }
    return emailAddresses;
  }
}

My current test class looks like:

@isTest
public class TestReportParser{ 

    public TestReportParser(){ } 

    public static testMethod void MyTestReportParser(){ 
        string jsonString = '{"currency" : "ABC"}';
         List<String> mytestData; 
        ReportParser rpt = new ReportParser(); 
        ReportParser rp = new ReportParser(jsonString); 
        String mydata = rp.getHtmlTable(); 
        mytestData = rp.getHeader(); 
    }
}