ASP.Net Web sites Load Testing using Visual Studio Team system(VSTS)

By | October 22, 2009
This document demonstrates how to create a load test using Visual Studio Team System to simulate workload against web applications and analyze the performance metrics from the resultant load test.
Note 1:
Load Tests should be executed ONLY in VSTS 2008. The reason being dynamic parameters are not properly handled in VSTS 2005 which might result in any of the following listed common errors.

  • Context parameter ‘HIDDEN1._EVENTTARGET’ not found in the test context
  •  Request Failed: Context parameter ‘HIDDEN1._VIEWSTATE’ not found in the test context

These errors occur when the Web test attempts to use a hidden field in the Web test context that it was unable to locate and extract from a previous response page it received. The dynamic parameters change every time the web test runs which was not handled in VS 2005 and this is addressed in VS 2008.
Another common error expected during execution of a web test is “500 Internal Server” which indicates a bug in the Web application.
Note 2:

  • To set up complete test project and run both web tests as well as load tests start from Step 1 (Page 2)
  •  To execute an existing Load test, Start from Step 14 (Page 15) 

Step 1:
Creating a Test Project
Create a test project that will capture scenarios from web application simulating the workload. Name your project; by default it will have an empty unit test. We will add Web Test and Load Test to this project in later steps.
We create the test project by selecting new project option from File menu in VSTS IDE. Create New Project dialog box pops up prompting to create new test project.  In the New Project dialog box choose Test Project under Project Types pane and give appropriate name for project and click OK as shown below.

Creating Test Project
Step 2:
Creating a Web Test:
In this step, we’ll create Web Test. This web test will be used in Load Test. In the Solution Explorer,
Right click the project click Add and then click Web Test. This opens up a new instance of browser with special Web Test Recorder explorer bar as shown below
Creating a Web Test
Step 3:
Recording Web Test:
  1. In the new browser instance, on the address bar, enter the URL of website and hit enter button.
  2. Below screenshot shows a demo website which I use. This is part of scenario being recorded for subsequent playback.
  3. Once you open your website, browse pages to generate scenarios to be used later for load testing.
  4. Once the desired actions are recorded, close the browser window and save the test.
Recording Web Test
Automatically, the project will now include the Web test case file along with each of the recorded requests as shown below
Generated Web Test Case
Step 4:
Running a Web Test:
  1. In the main window of Web test click the Run Test button in the left hand corner. Or you can right click the Web test and choose the option Run Web Test.
  2. The Web test will be run for a single user, and result displayed in the main window as shown in the figure.
  3. This will open up the Test Results windows and mark each test as pending while it is in progress and Passed/Failed once execution completes.  You can view test results in Test Results window tucked at the bottom as shown below
Running Web Test
Step 5:
Adding Load Test:
In this step, we’ll add the Load Test to the existing project. We will then set various properties of your Load Test in subsequent steps.
  1. In Solution Explorer, right-click the project node. Select Add, and then click Load Test.
  2. The New Load Test Wizard starts.
  3. The Welcome page of the New Load Test Wizard is the first page.
  4. Click Next.
New Load Test Wizard
Step 6:
Specify Scenario Settings:
Configuring Think time for Load Test
The choice of Think Time Profiles depends upon intend of usage.
  • By choosing to use recorded think times, Think times are used exactly as they were recorded in the Web test. Because a load test simulates multiple users, using the same think time could create an unnatural load pattern of synchronized virtual users.
  • By choosing normal distribution, think times are used, but varied on a normal curve. Provides a more realistic simulation of virtual users by slightly varying the think time between requests. Normal distribution will simulate more realistically the usage of the Web application where users will differ in think time fluctuation.
Step 7:
Specify Load Pattern Settings:
In this step, you will set the load pattern, with the number of concurrent users. The number of concurrent users represents the business volume like total number of users – sessions in a given time; we’ll use default Constant Load Pattern for our case. Instead, we can also use a Step load Pattern as necessitated by the situation.
Load Pattern Settings
Step 8:
Specify Test mix model for Load Test
Specify Test mix model
  • Based on total number of tests:
  • This model of test mix determines which test is run when a virtual user starts a test iteration. At the end of the load test, the number of times that a particular test was run matches the assigned test distribution
          Based on number of virtual users:
  • This model of test mix determines the percentage of virtual users who will run a particular test. At any point in the load test, the number of users who are running a particular test matches the assigned distribution. Follow this model when you’re basing the test mix on the percentage of users running a particular test.
          Based on user pace:
  • Over the course of load test, each test is run the specified number of times per user per hour. Follow this model when you want virtual users to run tests at a certain pace throughout the load test.
Step 9:
Add Web Test to Load Test:
Adding Web Test to Load Test
  1. In the Add tests to a load test scenario and edit test mix screen, Click the Add button.
  2. In the Add Tests dialog box that opens, in the Available tests list box, select the Web test created in previous steps and then click the right arrow to move it to the selected tests list box.
  3. In the Add Tests dialog box, click OK
Step 10:
Specify Browser Mix:
In this step, you add the browser mix by specifying types of browsers being used and distribution ratio for each type of browser.
  1. From the drop-down list of browser types, select the IE 6.0 browser to add to the mix.
  2. Our Load testing uses IE browser exclusively so the distribution of 100%
  3. Then click Next.
Browser Settings
Step 11:
Specify Network Mix:
In this step, you add the network mix by specifying types of network, on which the application is accessed and distribution ratio for each type of network.
  1. Typically in our scenario, we’ll be accessing from across LAN for testing purpose, so our network mix consists of LAN
  2. From the Network Type drop down, select the LAN type
  3. Then click Next.
Specifying Network Mix
Step 12:
Specify target computer and counter settings
In this step, you will specify the performance counters to be used for capturing load test results, in order to validate your tests against the objectives
Click Add computer, enter the computer name or IP address. Click on the check box on the left side of the computer. The default counters will be displayed. You may continue to add other computers that need to be monitored.
Computer and Performance counters settings
Select the check boxes, Application, ASP.Net and .NET application. Select the counters applicable to different servers, marking the check boxes on the counters under the machine chosen
Configuring the Performance counters
Step 13:
Specifying Run time Settings:
In this step, specify set of properties which determine how the Load test runs. The run settings determine the length of the test, warm-up duration, maximum number of error details reported, sampling rate, validation level etc.
  1. On the Run Settings page choose your initial settings.
  2. Set the Warm-up duration as 5 minutes.
  3. Set Run duration 10 minutes (can vary in actual load test)
  4. In the Description edit box specify the description of the Run Settings.
  5. Accept the other default settings.
  6. Click Finish. Your Load test is opened in the Load Test Editor.
Review and Edit run settings for a load test
Step 14:
Run the Load Test:
In this step you run the Load test to see, how the Web application responds to the web test, under the load simulation.
  1. In the Load Test Editor right click on the Load Test and select Run Test option.
  2. Click View menu in main window then select Full Screen, this will maximize the viewable area.
  3. Once the Load test is complete, it displays a message, “Load Test ‘LoadTest1’ is complete. The test data currently displayed only represents a portion of the available results. Would you like to view the detailed results from the load test result store?”
  4. Click Yes on the message.
Load Test in Progress
Dialog Box shows up asking for detailed results from load test result store
Step 15:
Analyze Test Results:
  • Analyze if the number of tests completed and failed tests are meeting the performance goals as identified in the Performance Goals section. Click on tables then tests
The number of Demo_Browse completed scenarios is 713 which mean total numbers of 713 tests are posted.
Test Results in Tables Format
Load Test Results in Graph format
                Key Indicators parameter values
  • Key Indicators from a closer view
Load Test Summary
Load Test Summary Continued
Processor Time and Memory Usage counters:
Following test results are from different web tests created from web application. These results vary from the above results.
RUN 1:
Controller and Agents Resources
Machine Name
% Processor Time
Available Memory at Test Completion (Mb)
Test Results
Total Tests
Failed Tests (% of total)
Avg. Test Time (sec)
0 (0)
0 (0)
0 (0)
Load Test Summary Continued
RUN 2:
Controller and Agents Resources
Machine Name
% Processor Time
Available Memory at Test Completion (Mb)
Test Results
Total Tests
Failed Tests (% of total)
Avg. Test Time (sec)
0 (0)
0 (0)
0 (0)
0 (0)
At a Glance:
We can also specify threshold values for performance counters like specifying processor time and errors to watch for critical levels.
Session duration is sometimes important. The modeled Demo_Browse scenario session time is negligible.
Adopt an incremental approach esp. for Think times and number of users so as to model the work load accurately and precisely.