Software testing in Visual Studio Team System 2008
Before going into the details of the actual testing using Visual Studio 2008, we need to understand the different tools provided by Visual Studio Team System (VSTS) and their usage. Once we understand the tools usage, then we should be able to perform different types of testing using VSTS. As we go along creating a number of different tests, we will encounter difficulty in managing the test similar to the code and its different versions during application development. There are different features such as the Test List Editor and Test View and the Team Foundation Server (TFS) for managing and maintaining all the tests created using VSTS. Using this Test List Editor, we can group similar tests, create number of lists, add, or delete tests from the list.
The other aspect of this article is to see the different file types getting created in Visual Studio during testing. Most of these files are in XML format, which get created automatically whenever the corresponding test is created.
The tools such as the Team Explorer, Code Coverage, Test View, and Test Results are not new to Visual Studio 2008 but actually available since Visual Studio 2005. While we go through the windows and their purposes, we can check the IDE and the tools integration into Visual Studio 2008.
Testing as part of Software Development Life Cycle
The main objective of testing is to find the defects early in the SDLC. If the defect is found early, then the cost will be less, but if the defect is found during production or implementation stage, then the cost will be higher. Moreover, testing is carried out to assure the quality and reliability of the software. In order to find the defect earlier, the testing activities should start early, that is, in the Requirement phase of SDLC and continue till the end of SDLC.
In the Coding phase, various testing activities takes place. Based on the design, the developers start coding the modules. Static and dynamic testing is carried out by the developers. Code reviews and code walkthroughs are also conducted.
Once the coding is completed, then comes the Validation phase, where different phases or forms of testing are performed.
- Unit Testing: This is the first stage of testing in SDLC. This is performed by the developer to check whether the developed code meets the stated requirements. If there are any defects, the developer logs them against the code and fixes the code. The code is retested and then moved to the testers after confirming the code without any defects for the piece of functionality. This phase identifies a lot of defects and also reduces the cost and time involved in testing the application and fixing the code.
- Integration Testing: This testing is carried out between two or more modules or functions together with the intent of finding interface defects between them. This testing is completed as a part of unit or functional testing, and sometimes becomes its own standalone test phase. On a larger level, integration testing can involve putting together groups of modules and functions with the goal of completing and verifying that the system meets the system requirements. Defects found are logged and later fixed by the developers. There are different ways of integration testing such as top-down testing and bottom-up testing:
- The Top-Down approach is followed to test the highest level of components and integrate first to test the high-level logic and the flow. The low-level components are tested later.
- The Bottom-Up approach is the exact opposite of the top-down approach. In this case, the low-level functionalities are tested and integrated first and then the high-level functionalities are tested. The disadvantage in this approach is that the high-level or the most complex functionalities are tested later.
- The Umbrella approach uses both the top-down and bottom-up patterns. The inputs for functions are integrated in the bottom-up approach and then the outputs for the functions are integrated in the top-down approach.
- System Testing: It compares the system specifications against the actual system. The system test design is derived from the system design documents and is used in this phase. Sometimes, system testing is automated using testing tools. Once all the modules are integrated, several errors may arise. Testing done at this stage is called system testing. Defects found in this testing are logged and fixed by the developers.
- Regression Testing: This is not mentioned in the testing phase, but is carried out once the defects are fixed by the developers. The main objective of this type of testing is to determine if bug fixes have been successful and have not created any new problems. Also, this type of testing is done to ensure that no degradation of baseline functionality has occurred and to check if any new functionality was introduced in the software.
Types of testing
Visual Studio provides a range of testing types and tools for software applications. Following are some of those types:
- Unit test
- Manual test
- Web test
- Load test
- Stress test
- Performance test
- Capacity Planning test
- Generic test
- Ordered test
In addition to these types, there are additional tools provided to manage, order the listing, and execute tests created in Visual Studio. Some of these are the Test View, Test List Editor, and the Test Results window. We will look at these testing tools and the supporting tools for managing the testing in Visual Studio 2008 in detail later.
As soon as the developer finishes the code, the developer wants to know if it is producing the expected result before getting into any more detailed testing or handing over the component to the tester. The type of testing performed by the developers to test their own code is called Unit testing. Visual Studio has great support for Unit testing.
The main goal of the unit testing is to isolate each piece of the code or individual functionality and test if the method is returning the expected result for different set of parameter values. It is extremely important to run unit tests to catch the defects in the early stage.
The methods generated by the automated unit testing tool call the methods in the classes from the source code and test the output of each of the methods by comparing them with the expected values. The unit test tool produces a separate set of test code for the source. Using the test code we can pass the parameter values to the method and test the value returned by the method, and then compare them with the expected result.
Unit testing code can be easily created by using the code generation feature, which creates the testing source code for the source application code. The generated unit testing code will contain several attributes to identify the Test Class, Test Method, and Test Project. These attributes are assigned when the unit test code gets generated from the original source code. Then using this code, the developer has to change the values and assert methods to compare the expected result from these methods.
The Unit test class is similar to the other classes in any other project. The good thing here is that we can create new test classes by inheriting the base test class. The base test class will contain the common or reusable testing methods. This is the new Unit testing feature which helps us reduce the code and reuse the existing test classes.
Whenever any code change occurs, it is easy to figure out the fault with the help of Unit tests, rerun those tests, and check whether the code is giving the intended output. This is to verify the code change the developer has made and to confirm that it is not affecting the other parts of the application.
All the methods and classes generated for the automated unit testing are inherited from the namespace Microsoft.VisualStudio.TestTools.UnitTesting.
Manual testing is the oldest and the simplest type of testing, but yet very crucial for software testing. It requires a tester to run all the tests without any automation tool. It helps us to validate whether the application meets various standards defined for effective and efficient accessibility and usage.
Manual testing comes to play in the following scenarios:
- There is not enough budget for automation.
- The tests are more complicated, or are too difficult to be converted into automated tests.
- The tests are going to be executed only once.
- There is not enough time to automate the tests.
- Automated tests would be time-consuming to create and run.
Manual tests can be created either using a Word document or Text format in Visual Studio 2008. This is a form of describing the test steps that should be performed by the tester. The step should also mention the expected result out of testing the step.
Web tests are used for testing the functionality of the web page, web application, web site, web services, and a combination of all these. Web tests can be created by recording the interactions that are performed in the browser. These can be played back to test the web application. Web tests are normally a series of HTTP requests (GET/POST).
There are different validation rules and extraction rules used in web testing. The validation rules are used for validating the form field names, texts, and tags in the requested web page. We can validate the results or values against the expected result as per business needs. These validation rules are also used for checking the time taken for the HTTP request.
At some point in time, we need to extract the data returned by the web pages. We may need the data for future use, or we may have to collect the data for testing purposes. In this case, we have to use the extraction rules for extracting the data returned by the page requested. Using this process, we can extract the form fields, texts, or values in the web page and store it in the web test context or collection.
Web tests cannot be performed only with the existence of a web page. We need some data to be populated from the database or some other source to test the web page functionality and performance. There is a data binding mechanism used in Web test, which is used for providing the data required for the requested page. We can bind the data from a database or any other data source. For example, the web page would be a reporting page that might require some query string parameters as well as the data to be shown in the page according to the parameters passed. To provide data for all these data-driven testing, we have to use the concept of data binding with the data source.
Web tests can be classified into Simple Web tests and Coded Web tests. Both these are supported by VSTS.
- Simple Web tests are very simple to create and execute. It executes on its own as per the recording. Once the test is started, there won’t be any intervention. The disadvantage is that it is not conditional. It’s a series of valid flow of events.
- Coded Web tests are bit more complex, but provide a lot of flexibility. For example, if we need some conditional execution of tests based on some values then we have to depend on this coded web test. These tests are created using either C# or Visual Basic code. Using the generated code we can control the flow of test events. But the disadvantage is its high complexity and maintenance cost.
Load testing is a method of testing used in different types of testing. The important thing with Load testing is that it is about performance. This type of testing is conducted with other types of testing, which means that it can be performed along with either Web testing or Unit testing.
The main purpose of load testing is to identify the performance of application based on different scenarios. Most of the time, we can predict the performance of the application that we develop, if it is running on one machine or a desktop. But in the case of web applications such as online ordering systems, we know the estimated maximum number of users, but do not know the connection speeds and location from where the users will access the web site. For such scenarios, the web application should support all the end users with good performance irrespective of the system they use, their Internet connection, the place, and the tool they use to access the web site.
So before we release this web site to the customers or the end users, we should check the performance of the application so that it can support the mass end user group. This is where load testing will be very useful in testing the application along with Web test or Unit test.
When a Web test is added to a Load test, it will simulate multiple users opening simultaneous connections to the same web application and making multiple HTTP requests. Load testing in Visual Studio comes with lots of properties which can be set to test the web application with different browsers, different user profiles, light loads, and heavy loads. Results of different tests can be saved in a repository to compare the set of results and improve their performance.
In case of client server and multi-tier applications, we will be having a lot of components which will reside in the server and serve the client requests. To get the performance of these components, we have to make use of a Load test with a set of Unit tests. One good example would be to test the data access service component that calls a stored procedure in the backend database and returns the results to the application that is using this service.
Load tests can be run either from the local machine or by submitting to a rig, which is a group of computers used for simulating the tests remotely. A rig consists of a single controller and one or more agents.
Load tests can be used in different scenarios of testing:
- Stress testing: This checks the functionality of the application under heavy load. The resource provided to the application could vary based on the input file size or the size of the data set, for example, uploading a file which is more than 50MB in size.
- Smoke testing: This checks if the application performs well for a short duration with a light load.
- Performance testing: This checks the responsiveness and throughput of the application with different loads.
- Capacity Planning test: This checks the application performance with various capacities.
As we know, there are different types of testing required to build quality software. We take care of running all these tests for the applications we develop. But we also have an order in which to execute all these different tests. For example, we do the unit testing first, then the integration test, then the smoke test, and then we go for the functional test. We can order the execution of these tests using Visual Studio.
Another example would be to test the configurations for the application before actually testing the functionality of the application. If we don’t order the test, we would never know whether the end result is correct or not. Sometimes, the tests will not go through successfully if the tests are not run in order.
Ordering of tests is done using the Test View window in Visual Studio. We can list all the available tests in the Test View and choose the tests in the same order using different options provided by Visual Studio and then run the tests. Visual Studio will take care of running the tests in the same order we have chosen in the list.
So once we are able to run the test successfully in an order, we can also expect the same ordering in getting the results. Visual Studio provides the results of all the tests in a single row in the Test Results window. Actually, this single row result will contain the results of all the tests run in the order. We can just double-click the single row result to get the details of each tests run in the ordered test.
Ordered test is the best way of controlling the tests and running the tests in an order.
We have seen different types and ways of testing the applications using VSTS. There are situations where we might end up having other applications for testing, which are not developed using Visual Studio. We might have only the executables or binaries for those applications. But we may not have the supported testing tool for those applications. This is where we need the generic testing method. This is just a way of testing third-party applications using Visual Studio.
Generic tests are used to wrap the existing tests. Once the wrapping is done, then it is just another test in VSTS.
Using Visual Studio, we can collect the test results, and gather the code coverage data too. We can manage and run the generic tests in Visual Studio just like the others tests.