[SalesForce] Code Coverage for JSON.Deserialize object in apex test classes in salesforce

I am writing test classes for apex classes code coverage.
In one apex class, I am sending request to a website and getting response in json format. Then I am deserializing the response string into inner-class objects. That portion is not being covered by me.

My Apex class code is:

public class SearchCompanyApex {
    public SearchResultJSON sJsonR{get;set;}
    public string myAPIKey {get; set;}
    public List<IncomeStatement> listIncomeStateValues{get;set;}

    public string result_of_httpReq {get; set;}


    public void loadPage(){
        string symbol = queryString('c');

        if(symbol !=null || symbol !='' ){                                                     
            generalInfo(symbol);    
        }
    }

    // Method that is requesting the data from website and assigning the data to variables of this class..
    private void generalInfo(string symbol){

        result_of_httpReq =  httpReq(symbol);
        sJsonR = (SearchResultJSON)JSON.deserialize(result_of_httpReq, SearchResultJSON.class);

    //=================== Not Covered code Start ================== Main is sJsonR.items[0].attributes not covered...  

        // Adding values in list to use it to save data in salesforce..  
        listIncomeStateValues = new List<IncomeStatement>{
            new IncomeStatement('Description', sJsonR.items[0].description,'Description__c'),
            new IncomeStatement('Company Title', sJsonR.items[0].title,'Name')
        };

    //=================== Not Covered code End  ===================

    }


    // Class to make a json obect containing the inoformation of all the fields of this class..
    public Class SearchResultJSON{
        public List<SearchedDocs> items;
    }

    public Class SearchedDocs{
        public string description{get;set;}
        public string title {get;set;}
        public list<list<string>> data{get;set;}
    }


    // Wrapper Class for CompaniesHouse Data 
    Public Class IncomeStatement{
        Public String Field{get;set;}
        Public String Value{get;set;}
        Public String SFField{get;set;}
        Public String SFValue{get;set;}


       // Constructor. Initializing values...
        public IncomeStatement(string Field, string Value,string SFField){
            this.Field = Field;
            this.Value = Value;
            this.SFValue = Value;
            this.SFField = SFField;
        }
    }
}

And Test Class code is:

@isTest
public with sharing class SearchCompanyApex_TestClass {

     static testMethod void myTest() {

        // Making object of class to be covered...
        SearchCompanyApex class_test = new SearchCompanyApex();

        // Making object of inner class of target class to be covered...
        SearchCompanyApex.SearchedDocs jsonobject_test = new SearchCompanyApex.SearchedDocs();
        jsonobject_test.description = 'Company description';
        jsonobject_test.title = 'Company Name';

        // Making list for different objects to map into fields...
        List<SearchCompanyApex.IncomeStatement> listJSONDocs = new List<SearchCompanyApex.IncomeStatement>();

        SearchCompanyApex.IncomeStatement list_description = new SearchCompanyApex.IncomeStatement('Description', jsonobject_test.description, 'Description__c');
        SearchCompanyApex.IncomeStatement list_company_title = new SearchCompanyApex.IncomeStatement('Company Title', jsonobject_test.title, 'Name');

        listJSONDocs.add(list_description);
        listJSONDocs.add(list_company_title);

        class_test.listIncomeStateValues = listJSONDocs;
        // Checking whether Website API key is equal to the saved key...    
        System.assertEquals(class_test.listIncomeStateValues, listJSONDocs);


        // It is the main part of this test class. It is call to "getAPIKeyMock" to avoid error : "Methods defined as TestMethod do not support Web service callouts." 
        Test.setMock(HttpCalloutMock.class, new GetAPIKeyMock(class_test.result_of_httpReq));

        // Calling the method "loadPage()" ...
        class_test.loadPage(); 


        SearchCompanyApex.SearchResultJSON jsonList_test = new SearchCompanyApex.SearchResultJSON();
        jsonList_test.items.add(jsonobject_test);

        class_test.sJsonR.items[0].title = jsonList_test.items[0].title;
        class_test.sJsonR.items[0].description = jsonList_test.items[0].description;


        // Checking whether Website API key is equal to the saved key...    
        System.assertEquals(class_test.sJsonR.items[0].title, 'Company Name');

        // Checking whether Website API key is equal to the saved key...    
        System.assertEquals(class_test.sJsonR.items[0].description, 'Company description');

    }


    // This is an inner class to handle WebService callout problems.
    private class GetAPIKeyMock implements HttpCalloutMock {
        private string returned_SJSONResult;

        public GetAPIKeyMock(string returned_SJSONResult) {
            this.returned_SJSONResult = returned_SJSONResult;
        }

        public HTTPResponse respond(HTTPRequest req) {
            // you can use System.assert here and "if" calls to check the request and affect your return if you wish

            HttpResponse res = new HttpResponse();
            res.setBody(returned_SJSONResult);
            return res;
        }
    }
}

Note: The uncovered code in shown in comments…
How can we cover this code?
Please tell me. Any help will be appreciated.