What are the benefits of creating multiple actions within any virtual user script?

It is one of the most frustrating things when your software system or application crashes once the whole software development life cycle or SDLC is over while the user tries to install it. 

You can just make out what impression it will have of your work and efforts on the user!

- Time wasted!

- Reputation spoiled!

- No benefits!

Nowadays to avoid such kind of situations and inconvenience to the users, a standard procedure of QA (quality assurance) has been defined to test the software systems and applications. 

In previous years, the task of software testing was thought to be an ultimate drudgery but now it has all been eased with the help of automated testing tools and one of them being the VU or virtual user. 

In this article we shall discuss about virtual user as well as the benefits one can have of creating multiple actions within any virtual user script. 

What is Virtual User?

- Emulating a real world human user becomes such an easy task with the help of virtual user which otherwise will take up a lot of time.

- A virtual user can almost perform most of the actions that are performed by a human user like:

1. Clicking the mouse
2. Hovering or pointing the mouse over some object on the screen.
3. Typing the words and commands.
4. Selecting some object.

- The system on which the virtual user software package is installed acts as the host computer and one more computer is paired with this one called the target system. 

- The responsibility of the host system is to control the other computers present in the network while the target computer is programmed to receive the instructions from the host computer. 

- In the environment of the virtual user, the software system or application takes up the task of compiling and running the scripts called virtual user scripts.

Benefits of creating multiple actions with virtual user script

Now coming to the benefits of creating multiple actions within a virtual user script:

1. Creating multiple actions within a VU script becomes quite effective when employed in tests that are highly repetitive and consist of many variations.
2. With the multiple action feature, more and more tasks can be performed which otherwise would be quite a tedious job to do for the human users. But for a system it is possible since it does not bother itself with tiredness, tediousness and thus proving itself as an ideal tester.
3. Another benefit of the multiple actions in one virtual user script is that such tests can be created which can be run at almost every internal build of the software system or application under question in the stages like:

a)   Development stage

b)   Alpha stage

c)   Beta stage

d)   Final release stage

4. With a virtual user script with multiple actions it can be easily verified that no functionality was broken by the code changes that were made to the earlier version of the software system or application.
5. With the help of multiple actions containing virtual user scripts, an automatic bug verification mechanism can be set up by imitating the steps through which a bug can be reproduced.
6. The automatic big verification test thus developed can be used to test each and every release of the software system or application thus ensuring that the bug has been fixed and there are no chances of it sneaking back in to the program code.
7. These multiple actions scripts can be split in to single ones whenever required. 

What is virtual user script? Why do you need to parametrize fields in your virtual user script?

Nowadays, the concept of the virtual user is quite common in the field of load testing. 

What is a Virtual User?

- Virtual user is one of the quite useful tools have been ever invented in the field of software engineering. 

- Virtual users can be used in a number of ways for testing load, stress or capacity of any software system or application you want. 

- It will be the easiest to define a virtual user as a virtualized representation of a real world user which has been specifically designed for simulating the same interactions and behaviors with the software system or application or web site to be tested in a way that a real world user would do exactly. 

Let us take an example, suppose at a peak your web site got 100 users over a particular hour. It becomes quite easy for you to simulate the same behavior using 100 virtual users making use of the scripts that invoke quite similar interaction and the navigation exactly as your real users do. Today such virtual users are also available that can playback the recorded scripts. 

In this article we discuss about what a virtual user script is and what is the need for parameterizing the fields in a virtual user script.  

What is a Virtual User Script & Need to Parametrize fields?

The fact that almost all of the scripts of the virtual user are automated is quite common. 

- For each and every automated script a particular entry point is marked by the script statement in virtual user. 

- From this point, the actions of the automated scripts are much similar to that of the real world users. 

- At any point these virtual user scripts can be made to click on any of the buttons or the windows, type some words, and move the mouse around and so on.

- Not only scripts, there are certain functions that are supported well by the virtual user and these functions can act as an extension to the virtual user scripts. 

- These functions have been given a general name called “tasks”. 

- These tasks consist of a procedure along with a list of parameters and in some cases they may also include an optional return value. 

- The information regarding the environment of the target computer is also collected by the virtual user with help of a statement called the match statement. 

- A specific environment element is searched by this match statement with the help of some descriptor traits like the following:

1. Static text
2. Edit text
3. Pictures
4. Icons
5. User items and so on.

- There is one more kind of statement that is used and is called the collect statement.

- It is used to collect all elements of a certain type in to the list.

- Afterwards the virtual user interacts with the software system or application environment using certain keywords like:

1. Select
2. Drag
3. Type
4. Close
5. Click and so on.

- Common objects of the operating system like windows, buttons, bars, menus and scrolls are accessed by the virtual users. 

- The virtual user software package comes with a log file feature using which one can write out all the information from within a script. 

- This feature also provides the scripter with information regarding the current run time state of the virtual user scripts. 

- These virtual user scripts can also be debugged whenever required by logging with the printh statement. 

Another fact about virtual user is that there exists no type checking which serves as a very good idea to log the parameters that serve as input to every task.

How can data caching have a negative effect on load testing results?

It is quite a heavy task to retrieve data from a certain repository if we see it through a performance point of view. It becomes much more difficult when the data repository lies too far from the application server.Retrieving data becomes difficult also when a specific type of data is accessed over and over again. 

Caching is a technique that has been developed as a measure for reducing the work load and the time consumed for retrieval of the data. 

In this article, we have discussed about the negative effects that simple data caching can have up on the load testing. 

Rules for Caching Concepts

Some rules have been laid down for the caching concepts which have been mentioned below:

1. The data caching is useful if used only for a short period of time and does not works when used through the life cycle of the software system or application.

2. Only that data which is not likely to be changed quite often should be cached.

3. There are certain data repositories that have the capability of supporting the notification events in case if the modification of the data takes place outside the application.

If these above stated rules are not followed properly, the data caching is sure to have a negative impact up on the load testing. 

How data caching produces a negative impact on load testing?

- This is so because the data caching has got some pitfalls which come in our observation only when there are potential situations when there is a possibility of data expiry and software system or application using inconsistent data. 

- Using caching technique is quite simple but any fault can cause an impact on load testing.

- Load testing involves putting demands on the software system or application in order measure its response. 

- The outcomes of the load testing helps in measuring the difference between the responses of the software system or application under normal as well as peak load conditions. 

- Load testing is usually used as a means to have a measure of the maximum capacity at which the software system or application can operate easily. 

- Data caching initiates quick response from the software system or application for obtaining cookies etc. 

- Though data caching responds faster than the usual memory transactions, it has a negative impact on the result of the load testing i.e. you will not get the original results rather the results you will get will be the altered ones. 

What you will get to see is the wrong performance of the software system or application. 

What is the purpose of caching?

- Caching is done with the purpose of storing certain data so that that data in the subsequent stages can be served faster. 

- Data caching affects load testing results in a way until and unless the cache is cleared up by the testing tool after every iteration of the virtual user, an artificial faster page load time is started to be given by the caching mechanism. 

- Such artificial timings will alter your load testing results and invalidate them. - In caching, all the recently visited web pages are stored. 

- When we carry out load testing, our aim is always to check the software system or application under load. 

- So if by chance the caching option is left enabled, what will happen is that the software system or application will try retrieving the data from the data that is locally saved giving false measure of the performance determination. 

- So, the caching option should always be disabled while you carry out load testing. 

Overview of Mercury Interactive's LoadRunner and its Components

To test the performance requirements such as transaction response time of a database application or response time in the case of multiple users accessing a web site, LoadRunner is an excellent tool that reduces the infrastructure and manpower costs.
Mercury Interactive's LoadRunner is used to test the client/server applications such as databases and websites. Using LoadRunner, with minimal infrastructure and manpower, performance testing can be carried out.
- LoadRunner simulates multiple transactions from the same machine and hence it creates a scenario of multiple simultaneous access to to the application. So, instead of t=real users, virtual users are simulated. With virtual users simultaneously accessing the application, LoadRunner accurately measures and analyzes the performance of the client/server application.
In LoadRunner, we divide the performance testing requirements into various scenarios. A scenario is a series of actions that are to be tested. LoadRunner creates virtual users. The Vusers submit the requests to the server. Vuser script is generated and this script is executed for simulating multiple users.

LoadRunner Components

LoadRunner contains the following components:
- The Virtual User Generator captures end-user business processes and creates
an automated performance testing script, also known as a virtual user script.
- The Controller organizes, drives, manages, and monitors the load test.
- The Load Generators create the load by running virtual users.
- The Analysis helps you view, dissect, and compare the performance results.
- The Launcher provides a single point of access for all of the LoadRunner
components.