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 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;

} }