BDD Specflow Object reference not set to an instance of an object in ObjectContainer.RegisterInstanceAs

Question

I have rearranged my class files and Webdriver variable so I can use Context Injection to share the Webdriver variable between steps. Before I was using SetupFixture, Setup and TearDown which is not correct for BDD. Trying Context Injection now with BeforeAllTests, BeforeTestRun etc. I am getting the error:

System.NullReferenceException: Object reference not set to an instance of an object

The line highlighted where the error is here:

[BeforeScenario]
        public void RunBeforeScenario()
        {
            objectContainer.RegisterInstanceAs<SeleniumContext>(seleniumContext);
        }

My setup.cs implementation is:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using TechTalk.SpecFlow;
using OpenQA.Selenium;
using OpenQA.Selenium.Support.PageObjects;
using OpenQA.Selenium.Firefox;
using SearchTest.Setup;
using BoDi;
using SearchTest.WebDriver;


namespace SearchTest.Setup
{
    [Binding]
    public class BeforeAllTests
    {
        private readonly IObjectContainer objectContainer;
        private static SeleniumContext seleniumContext;

        public BeforeAllTests(IObjectContainer container)
        {
            this.objectContainer = objectContainer;
        }

        [BeforeTestRun]
        public static void RunBeforeAllTests()
        {
            seleniumContext = new SeleniumContext();
        }

        [BeforeScenario]
        public void RunBeforeScenario()
        {
            objectContainer.RegisterInstanceAs<SeleniumContext>(seleniumContext);
        }
    }
}

My HomePage class HomePage.cs implementation is:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using OpenQA.Selenium;
using OpenQA.Selenium.Support.PageObjects;
using OpenQA.Selenium.Firefox;
using NUnit.Framework;
using SearchTest.Setup;
using SearchTest.WebDriver;
using TechTalk.SpecFlow;
using BoDi;


namespace SearchTest.PageObjects
{
    [Binding]
    public class HomePage : PageObjectBase 
    {
        private SeleniumContext seleniumContext;
        //private IWebDriver driver{ get; set; }

        [FindsBy(How = How.XPath, Using = ".//TITLE")]
        public IWebElement Title{ get; set; }

        // search text field on the homepage
        //[FindsBy(How= How.Id, Using="twotabsearchtextbox")]
        //private IWebElement Searchfield_ID { get; set; }

        [FindsBy(How = How.XPath, Using = ".//*[@id='twotabsearchtextbox']")]
        private IWebElement Searchfield_XPATH { get; set; }

        [FindsBy(How = How.Id, Using = "nav-search-submit-text")]
        private IWebElement SearchButton { get; set; }

        [FindsBy(How = How.XPath, Using = ".//*[@id='nav-search']/form/div[2]/div/input")]
        private IWebElement searchButton_Xpath {get; set;}

//        public HomePage(IWebDriver driver)
        public HomePage(SeleniumContext seleniumContext)
            /*This is to reference the PageObjectBase Class.  Passing in the Title of the 
             * page that is expected for the HomePage to ensure the correct Page is loaded
             * before starting any tests.
             */
            //: base("Amazon.co.uk: Low Prices in Electronics, Books, Sports Equipment & more")
            : base(seleniumContext)


        {
           //driver = new FirefoxDriver();
           //Console.Out.WriteLine("from Homepage Constructor Driver.title in SearchResultsPage class = " + driver.Title);
           //driver.Manage().Timeouts().ImplicitlyWait(TimeSpan.FromSeconds(5)); // Set implicit wait timeouts to 5 secs
           //PageFactory.InitElements(driver, this);
            this.seleniumContext = seleniumContext;
            PageFactory.InitElements(seleniumContext.driver, this);
        }

    public void goToURL() {
        //driver.Navigate().GoToUrl("http://www.amazon.co.uk");
    }

    public void EnterSearchText(String text)
        {
            Searchfield_XPATH.SendKeys(text);
        }

    public SearchResultsPage click_search_button() {
        searchButton_Xpath.Click();
        return new SearchResultsPage(seleniumContext);
    }
   }   
}

Steps class SearchSteps.cs implementation is:

using System;
using TechTalk.SpecFlow;
using OpenQA.Selenium;
using OpenQA.Selenium.Firefox;
using NUnit.Framework;
using SearchTest.PageObjects;
using SearchTest.WebDriver;

namespace SearchTest
{
    [Binding]
    public class SearchSteps
    {
        private SeleniumContext seleniumContext;
        private IWebDriver driver { get; set; }
        PageObjects.HomePage home_page { get; set; }
        private SearchResultsPage search_results_page;

    [Given(@"I navigate to the page ""(.*)""")]
    public void GivenINavigateToThePage(string p0)
        home_page = new PageObjects.HomePage(seleniumContext);
        //home_page.goToURL();
    }

    [Given(@"I see the page is loaded")]
    public void GivenISeeThePageIsLoaded()
    {
        //Assert.AreEqual("http://localhost:8080: PS4 products", driver.Title);

    }

    [When(@"I enter Search Keyword in the Search Text box")]
    public void WhenIEnterSearchKeywordInTheSearchTextBox(Table table)
    {
        //string search_text = table.Rows[0]["Keyword"].ToString();
        //driver.FindElement(By.Id("twotabsearchtextbox")).SendKeys(search_text);
        //SearchResultsPage SearchResultsPage = home_page.EnterSearchText("F1");
        home_page.EnterSearchText("F1");
    }

    [When(@"I click on Search Button")]
    public void WhenIClickOnSearchButton()
    {
        //driver.FindElement(By.Name("BtnG")).Click();
        search_results_page = home_page.click_search_button();
    }

    [Then(@"Search items shows the items related to PS4")]
    public void ThenSearchItemsShowsTheItemsRelatedToPS4()
    {
        //Assert.AreEqual("PS4", driver.FindElement(By.XPath(".//*[@id='desktop-auto-sparkle-multi']/div/a")).Text);
        //Assert.AreEqual("PS4", driver.FindElement(By.XPath("//h2[contains(text(), "PS4")]")));
        search_results_page.get_search_result_title();
    }
  }
}

How do I resolve this please? I think it is complaining that objectContainer.RegisterInstanceAs does not have any value, it is Null. It has not been instantiated?

Thanks, Riaz

Answer 1

your problem is that you have a typo in your constructor. This:

public BeforeAllTests(IObjectContainer container)
{
    this.objectContainer = objectContainer;
}

should be

public BeforeAllTests(IObjectContainer container)
{
    this.objectContainer = container;
}

you are not using the container instance given in the constructor, you are simply setting the objectContainer to itself.