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Coding a custom validation rule for a web performance test

 

You can create your own validation rules. To do this, you derive your own rule class from a validation rule class. Validation rules derive from the ValidationRule base class.

Visual Studio Enterprise provides some predefined validation rules. For more information, see Using Validation and Extraction Rules in Web Performance Tests.

Note

You can also create custom extraction rules. For more information, see Create custom code and plug-ins for load tests.

Requirements

  • Visual Studio Enterprise

To create custom validation rules

  1. Open a Test Project that contains a Web performance test.

  2. (Optional) Create a separate Class library project in which to store your validation rule.

    Important

    You can create the class in the same project that your tests are in. However, if you want to reuse the rule, it is better to create a separate Class library project in which to store your rule. If you create a separate project, you must complete the optional steps in this procedure.

  3. (Optional) In the Class library project, add a reference to the Microsoft.VisualStudio.QualityTools.WebTestFramework DLL.

  4. Create a class that derives from the ValidationRule class. Implement the Validate and RuleName members.

  5. (Optional) Build the new Class library project.

  6. (Optional) In the Test Project, add a reference to the Class library project that contains the custom validation rule.

  7. In the Test Project, open a Web performance test in the Web Performance Test Editor.

  8. To add the custom validation rule to a Web performance test request, right-click a request and select Add Validation Rule.

    The Add Validation Rule dialog box appears. You will see your custom validation rule in the Select a rule list, together with the predefined validation rules. Select your custom validation rule and then choose OK.

  9. Run your Web performance test.

Example

The following code shows an implementation of a custom validation rule. This validation rule mimics the behavior of the predefined Required Tag validation rule. Use this example as a starting point for your own custom validation rules.

Warning

Public properties in the code for a custom validator cannot have null values.

using System;  
using System.Diagnostics;  
using System.Globalization;  
using Microsoft.VisualStudio.TestTools.WebTesting;  
  
namespace SampleWebTestRules  
{  
    //-------------------------------------------------------------------------  
    // This class creates a custom validation rule named "Custom Validate Tag"  
    // The custom validation rule is used to check that an HTML tag with a   
    // particular name is found one or more times in the HTML response.  
    // The user of the rule can specify the HTML tag to look for, and the   
    // number of times that it must appear in the response.  
    //-------------------------------------------------------------------------  
    public class CustomValidateTag : ValidationRule  
    {  
        /// Specify a name for use in the user interface.  
        /// The user sees this name in the Add Validation dialog box.  
        //---------------------------------------------------------------------  
        public override string RuleName  
        {  
            get { return "Custom Validate Tag"; }  
        }  
  
        /// Specify a description for use in the user interface.  
        /// The user sees this description in the Add Validation dialog box.  
        //---------------------------------------------------------------------  
        public override string RuleDescription  
        {  
            get { return "Validates that the specified tag exists on the page."; }  
        }  
  
        // The name of the required tag  
        private string RequiredTagNameValue;  
        public string RequiredTagName  
        {  
            get { return RequiredTagNameValue; }  
            set { RequiredTagNameValue = value; }  
        }  
  
        // The minimum number of times the tag must appear in the response  
        private int MinOccurrencesValue;  
        public int MinOccurrences  
        {  
            get { return MinOccurrencesValue; }  
            set { MinOccurrencesValue = value; }  
        }  
  
        // Validate is called with the test case Context and the request context.  
        // These allow the rule to examine both the request and the response.  
        //---------------------------------------------------------------------  
        public override void Validate(object sender, ValidationEventArgs e)  
        {  
            bool validated = false;  
            int numTagsFound = 0;  
  
            foreach (HtmlTag tag in e.Response.HtmlDocument.GetFilteredHtmlTags(RequiredTagName))  
            {  
                Debug.Assert(string.Equals(tag.Name, RequiredTagName, StringComparison.InvariantCultureIgnoreCase));  
  
                if (++numTagsFound >= MinOccurrences)  
                {  
                    validated = true;  
                    break;  
                }  
            }  
  
            e.IsValid = validated;  
  
            // If the validation fails, set the error text that the user sees  
            if (!validated)  
            {  
                if (numTagsFound > 0)  
                {  
                    e.Message = String.Format("Only found {0} occurences of the tag", numTagsFound);  
                }  
                else  
                {  
                    e.Message = String.Format("Did not find any occurences of tag '{0}'", RequiredTagName);  
                }  
            }  
        }  
    }  
}  
Imports System  
Imports System.Diagnostics  
Imports System.Globalization  
Imports Microsoft.VisualStudio.TestTools.WebTesting  
  
Namespace SampleWebTestRules  
  
    '-------------------------------------------------------------------------  
    ' This class creates a custom validation rule named "Custom Validate Tag"  
    ' The custom validation rule is used to check that an HTML tag with a   
    ' particular name is found one or more times in the HTML response.  
    ' The user of the rule can specify the HTML tag to look for, and the   
    ' number of times that it must appear in the response.  
    '-------------------------------------------------------------------------  
    Public Class CustomValidateTag  
        Inherits Microsoft.VisualStudio.TestTools.WebTesting.ValidationRule  
  
        ' Specify a name for use in the user interface.  
        ' The user sees this name in the Add Validation dialog box.  
        '---------------------------------------------------------------------  
        Public Overrides ReadOnly Property RuleName() As String  
            Get  
                Return "Custom Validate Tag"  
            End Get  
        End Property  
  
        ' Specify a description for use in the user interface.  
        ' The user sees this description in the Add Validation dialog box.  
        '---------------------------------------------------------------------  
        Public Overrides ReadOnly Property RuleDescription() As String  
            Get  
                Return "Validates that the specified tag exists on the page."  
            End Get  
        End Property  
  
        ' The name of the required tag  
        Private RequiredTagNameValue As String  
        Public Property RequiredTagName() As String  
            Get  
                Return RequiredTagNameValue  
            End Get  
            Set(ByVal value As String)  
                RequiredTagNameValue = value  
            End Set  
        End Property  
  
        ' The minimum number of times the tag must appear in the response  
        Private MinOccurrencesValue As Integer  
        Public Property MinOccurrences() As Integer  
            Get  
                Return MinOccurrencesValue  
            End Get  
            Set(ByVal value As Integer)  
                MinOccurrencesValue = value  
            End Set  
        End Property  
  
        ' Validate is called with the test case Context and the request context.  
        ' These allow the rule to examine both the request and the response.  
        '---------------------------------------------------------------------  
        Public Overrides Sub Validate(ByVal sender As Object, ByVal e As ValidationEventArgs)  
  
            Dim validated As Boolean = False  
            Dim numTagsFound As Integer = 0  
  
            For Each tag As HtmlTag In e.Response.HtmlDocument.GetFilteredHtmlTags(RequiredTagName)  
  
                Debug.Assert(String.Equals(tag.Name, RequiredTagName, StringComparison.InvariantCultureIgnoreCase))  
  
                numTagsFound += 1  
                If numTagsFound >= MinOccurrences Then  
  
                    validated = True  
                    Exit For  
                End If  
            Next  
  
            e.IsValid = validated  
  
            ' If the validation fails, set the error text that the user sees  
            If Not (validated) Then  
                If numTagsFound > 0 Then  
                    e.Message = String.Format("Only found {0} occurences of the tag", numTagsFound)  
                Else  
                    e.Message = String.Format("Did not find any occurences of tag '{0}'", RequiredTagName)  
                End If  
            End If  
        End Sub  
    End Class  
End Namespace  
  

See Also

ValidationRule
Microsoft.VisualStudio.TestTools.WebTesting.Rules
ValidateFormField
ValidationRuleFindText
ValidationRuleRequestTime
ValidationRuleRequiredAttributeValue
ValidationRuleRequiredTag
Using Validation and Extraction Rules in Web Performance Tests
How to: Add a Validation Rule to a Web Performance Test
Adding validation and extraction rules to a web performance test
Coding a custom extraction rule for a web performance test