C# Exception: NullReferenceException

0
votes

I am getting the following message whilt running my test.

Message:

Test method Automation.Test1.General threw exception: System.NullReferenceException: Object reference not set to an instance of an object.

Automation.Library.CheckLogIn() in C:\Documents and Settings\Administrator\My Documents\Visual Studio 2010\Projects\Automation\Automation\Library.cs: line 152

Automation.Test1.General() in C:\Documents and Settings\Administrator\My Documents\Visual Studio 2010\Projects\Automation\Automation\Test1.cs: line 72

Library.cs (superclass)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Selenium;
using System.IO;
using System.Reflection;
using System.Net;
using System.Configuration;

namespace Automation
{
[TestClass]
public class Library
{
    public ISelenium Sel;

    // Open browser
    public void OpenBrowser(out ISelenium selenium, out StringBuilder verificationErrors)
    {
        selenium = new DefaultSelenium(GetAppConfig("TestMachine"), 4444, GetAppConfig("Browser"), GetAppConfig("URL"));
        selenium.Start();
        selenium.Open(GetAppConfig("URL"));
        verificationErrors = new StringBuilder();
    }

    // Returns the value of the passed key from App.config
    public string GetAppConfig(string key)
    {
        return ConfigurationManager.AppSettings[key].ToString();
    }

    // Check for  Login
    public void CheckLogIn()
    {
        if (Sel.IsElementPresent(GetAppConfig("SignOn")))
        {
            Sel.Type(GetAppConfig("UserNameField"), GetAppConfig("UserName"));
            Sel.Type(GetAppConfig("PWDField"), GetAppConfig("PWD"));
            Sel.Click(GetAppConfig("Go"));
        }

        else
        {
            // do nothing
        }
    }
}

}

Test1.cs (sub class)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Selenium;
using System.IO;
using System.Reflection;
using System.Net;
using System.Configuration;

namespace Automation
{
[TestClass]
public class Test1
{
    public ISelenium Sel;
    public StringBuilder Err;
    Boolean bNextFlag = false;
    Library Lib = new Library();

    // Constructor
    public Test1()
    {
        // Launch browser with application URL
        Lib.OpenBrowser(out Sel, out Err);
        Sel.WindowMaximize(); 
        Lib.CheckLogIn();
    }

    [TestMethod]
    public void General()
    {
        // Verify  Tab
        if (Sel.IsElementPresent(Lib.GetAppConfig("TAB")))
        {
            Sel.Click(Lib.GetAppConfig("TAB"));
            bNextFlag = true;
        }

        else
        {
           // do something
        }
    }
}

}

app.config.xml

<?xml version="1.0" encoding="utf-8" ?>


<add key="TestMachine" value="localhost"/>
<add key="Browser" value="*iexplore"/>
<add key="URL" value="http://localhost//Default.aspx"/>


<!-- CheckLogIn-->
<add key="SignOn" value="//*[@id=&quot;LogIn&quot;]"/>
<add key="UserNameField" value="//*[@id=&quot;username&quot;]"/>
<add key="PWDField" value="//*[@id=&quot;pwd&quot;]"/>
<add key="Go" value="//*[@id=&quot;gobutton&quot;]"/>
<add key="UserName" value="admin"/>
<add key="PWD" value="password"/>
<!-- End of  CheckLogIn-->

<!-- Object Definitions-->

<add key="TAB" value="//*[@id=&quot;Tab&quot;]"/>

<!-- End of Object Definitios-->

3
c#selenium

3 Answers

2
votes

Well I don't really see a question in your post, so I suppose I will point out the obvious...

Your error is telling you that you have a NullReferenceException being thrown somewhere in this method:

public void CheckLogIn()
{
    if (Sel.IsElementPresent(GetAppConfig("SignOn")))
    {
        Sel.Type(GetAppConfig("UserNameField"), GetAppConfig("UserName"));
        Sel.Type(GetAppConfig("PWDField"), GetAppConfig("PWD"));
        Sel.Click(GetAppConfig("Go"));
    }
    else
    {
        // do nothing
    }
}

Sel is null. Nowhere in your code do you actually initialize it. You'll need to initialize it somewhere like:

Sel = new SomeTypeThatImplementsISelenium();

Also, GetAppConfig is deprecated per the docs.

1
votes

Yeah you might need to initialize an instance of object before you can use any of its methods. An easy way to sort this out is to add a break point somewhere before the error is thrown, and use the watch window to initialize selenium and see what Sel.IsElementPresent(GetAppConfig("SignOn"))returns- true or false.

0
votes

public ISelenium Sel;

I can see Sel is defined but never assign value to it.