System.JSONException: no content to map to Object due to end of input in test class

Question

I'm working on two apex classes with use the HttpCalloutMock interface and they're working fine when I manually test, but I'm having trouble with the automated test class. Everything seems to look good, but I keep getting the following exception, any tips?

System.JSONException: no content to map to Object due to end of input

Class One

public class ReportDataComponentController{

  /*public String reportId{get;set;}
  public ReportWrapper__c reportWrapper {get{
    return reportWrapper();
  }set;}
  public String htmlBody {get{
    return generateReportData();
  }set;}*/

  public String reportId{get;set;}
  public Contact reportWrapper {get;set;}
  public String htmlBody {get;set;}

  public ReportDataComponentController(){
    reportId = '';
    htmlBody = '';
    reportWrapper = new Contact();
    if(ApexPages.currentPage().getParameters().containsKey('reportId')){
      reportId = ApexPages.currentPage().getParameters().get('reportId');            
    }
    populateReportWrapper();
    generateReportData();
  }

  Public void populateReportWrapper(){
    //ReportWrapper__c repWrapper = new ReportWrapper__c();
    for(Contact wrapper : [ Select id, name, email, firstname, lastname 
    from Contact
    where id = :reportId]){

      reportWrapper = wrapper; 

    }
    //return repWrapper;
  }

  public void generateReportData(){
    ReportCallout rptCallout = new ReportCallOut();
    String serverName = Apexpages.currentpage().getheaders().get('X-Salesforce-Forwarded-To');
    if(String.isBlank(serverName)) {
      serverName = 'prerelna1.pre.salesforce.com';
    }

    String json = rptCallout.getJSONFromReport(serverName, reportId);
    ReportParser reportParser = new ReportParser(json);

    htmlBody = reportParser.getHtmlTable();
    //return htmlExp;
  }
}

Class Two

global class ReportCallOut implements HttpCalloutMock {

  public String getJSONFromReport(String currentSFDCServerName,String reportID){
    //return getReportJSON();


    String baseURL = 'https://' + currentSFDCServerName +
                     + '/services/data/v29.0/analytics/reports/' + reportID + '?includeDetails=true';

    HttpRequest request = new HttpRequest();
    request.setMethod('GET');
    request.setEndPoint(baseURL);
    request.setHeader('Authorization','OAuth ' + UserInfo.getSessionID());
    request.setHeader('X-PrettyPrint','1');

    Http http = new Http();
    HttpResponse response = http.send(request);

    if(response.getStatusCode() == 200) {
        return response.getBody();
    }
    else
    {
        return null;
    }
  }

  global HttpResponse respond(HttpRequest request) {
    HttpResponse httpResponse = new HttpResponse();
    httpResponse.setStatusCode(200);
    //httpResponse.setBody(getReportJSON());

    return httpResponse;
  }

}

Test Class

@isTest
global class TestReportCallOutAndReportData{

    public TestReportCallOutAndReportData(){
    }

    static testMethod void TestReportCallAndReportData(){

        ReportCallOut rco = new ReportCallOut();
        String currentSFDCServerName;
        String reportID;
        HttpRequest hr = new HttpRequest();

        Test.setMock(HttpCalloutMock.class, new ReportCallOut());
        String srt = rco.getJSONFromReport(currentSFDCServerName,reportID);
        HttpResponse hrs = rco.respond(hr); 

        rco.getJSONFromReport(currentSFDCServerName,reportID);
        rco.respond(hr);

        String contentType = hrs.getHeader('Content-Type');
        String actualValue = hrs.getBody();
        String expectedValue = '{"foo":"bar"}';
        //System.assertEquals(actualValue, expectedValue);
        //System.assertEquals(200, hrs.getStatusCode());                 

        ReportDataComponentController rdcc = new ReportDataComponentController();
        rdcc.populateReportWrapper();
        rdcc.generateReportData();  


    }
}

Answer 1

You have to hard code the expected response in mock test class:

httpResponse.setBody('{"foo":"bar"}');

also make sure that the response must be a valid json.

The best way is copy the real result from system debug log and set it as response body in mock test class.