资源描述
International Journal of Software Engineering & Applications (IJSEA), Vol.3, No.1, January 2012
STUDY PAPER ON TEST CASE GENERATION FOR
GUI BASED TESTING
Isabella1and Emi Retna2
1
PG Research Scholar, Software Engineering Group, School of Computer Science and
Technology, Karunya University, Coimbatore, India
aisabella20@
2
Head – Computer Technology Centre, Karunya University, Coimbatore, India
emiretna@
ABSTRACT
With the advent of WWW and outburst in technology and software development, testing the software
became a major concern. Due to the importance of the testing phase in a software development lifecycle,
testing has been divided into graphical user interface (GUI) based testing, logical testing, integration
testing, etc.GUI Testing has become very important as it provides more sophisticated way to interact with
the software. The complexity of testing GUI increased over time. The testing needs to be performed in a
way that it provides effectiveness, efficiency, increased fault detection rate and good path coverage. To
cover all use cases and to provide testing for all possible (success/failure) scenarios the length of the test
sequence is considered important. Intent of this paper is to study some techniques used for test case
generation and process for various GUI based software applications.
KEYWORDS
GUI Testing, Model-Based Testing, Test Case, Automated Testing, Event Testing.
1. INTRODUCTION
Graphical User Interface (GUI) is a program interface that takes advantage of the computer's
graphics capabilities to make the program easier to use. Graphical User Interface (GUI) provides
user an immense way to interact with the software [1]. The most eminent and essential parts of
the software that is being used today are Graphical User Interfaces (GUIs) [8], [9]. Even though
GUIs provides user an easy way to use the software, they make the development process of the
software tangled [2].
Graphical user interface (GUI) testing is the process of testing software's graphical user interface
to safeguard it meets its written specifications and to detect if application is working functionally
correct. GUI testing involves performing some tasks and comparing the result with the expected
output. This is performed using test cases. GUI Testing can be performed either manually by
humans or automatically by automated methods.
Manual testing is done by humans such as testers or developers itself in some cases and it is often
error prone and there are chances of most of the test scenarios left out. It is very time consuming
also. Automated GUI Testing includes automating testing tasks that have been done manually
before, using automated techniques and tools. Automated GUI testing is more, efficient, precise,
reliable and cost effective.
A test case normally consists of an input, output, expected result and the actual result. More than
one test case is required to test the full functionality of the GUI application. A collection of test
cases are called test suite. A test suite contains detailed guidelines or objectives for each
collection of test cases.
Model Based Testing (MBT) is a quick and organized method which automates the testing
process through automated test suite generation and execution techniques and tools [11]. Model
based testing uses the directed graph model of the GUI called event-interaction graph (EIG) [4]
and event semantic interaction graph (ESIG). Event interaction graph is a refinement of event
flow graph (EFG) [1]. EIG contains events that interact with the business logic of the GUI
application. Event Semantic Interaction (ESI) is used to identify set of events that need to be
tested together in multi-way interactions [3] and it is more useful when partitioning the events
according to its functionality.
This paper is organized as follow: Section 2 provides some techniques, algorithms used to
generate test cases, a method to repair the infeasible test suites are described in section 3, GUI
testing on various types of softwares or under different conditions are elaborated in section 4,
section 5 describes about testing the GUI application by taking event context into consideration
and last section concludes the paper.
2. TEST CASE GENERATION
2.1. Using GUI Run-Time State as Feedback
Xun Yuan and Atif M Memon [3], used GUI run time state as feedback for test case generation
and the feedback is obtained from the execution of a seed test suite on an Application Under Test
(AUT).This feedback is used to generate additional test cases and test interactions between GUI
events in multiple ways. An Event Interaction Graph (EIG) is generated for the application to be
tested and seed test suites are generated for two-way interactions of GUI events. Then the test
suites are executed and the GUI’s run time state is recorded. This recorded GUI run time state is
used to obtain Event Semantic Interaction(ESI) relationship for the application and these ESI are
used to obtain the Event Semantic Interaction Graph(ESIG).The test cases are generated and
ESIGs is capable of managing test cases for more than two-way interactions and hence forth 2-,
3-,4-,5- way interactions are tested. The newly generated test cases are tested and additional faults
are detected. These steps are shown in Figure 1. The fault detection effectiveness is high than the
two way interactions and it is because, test cases are generated and executed for combination of
events in different execution orders.
There also some disadvantages in this feedback mechanism. This method is designed focusing on
GUI applications. It will be different for applications that have intricate underlying business logic
and a simple GUI. As multi-way interactions test cases are generated, large number of test cases
will be generated. This feedback mechanism is not automated.
Figure 1. Test Case Generation Using GUI Runtime as Feedback
2.2. Using Covering Array Technique
Xun Yuan et al [4], proposed a new automated technique for test case generation using covering
arrays (CA) for GUI testing. Usually 2-way covering are used for testing. Because as number of
events in a sequence increases, the size of test suite grows large, preventing from using sequences
longer than 3 or 4. But certain defects are not detected using this coverage strength. Using this
technique long test sequences are generated and it is systematically sampled at particular
coverage strength. By using covering arrays t-way coverage strength is being maintained, but any
length test sequences can be generated of at least t. A covering array, CA(N; t, k, v), is an N × k
array on v symbols with the property that every N × t sub-array contains all ordered subsets of
size t of the v symbols at least once.
As shown in Figure 2, Initially EIG model is created which is then partitioned into groups of
interacting events and then constraints are identified and used to generate abstract model for
testing. Long test cases are generated using covering array sampling. Event sequences are
generated and executed. If any event interaction is missed, then regenerate test cases and repeat
the steps.
The disadvantages are event partition and identifying constraints are done manually.
Figure 2. Test Generation Using Covering Array
2.3. Dynamic Adaptive Automated test Generation
Xun Yuan et al [5], suggested an algorithm to generate test suites with fewer infeasible test cases
and higher event interaction coverage. Due to dynamic state based nature of GUIs, it is necessary
and important to generate test cases based on the feedback from the execution of tests. The
proposed framework uses techniques from combinatorial interaction testing to generate tests and
basis for combinatorial interaction testing is a covering array. Initially smoke tests are generated
and this is used as a seed to generate Event Semantic Interaction (ESI) relationships. Event
Semantic Interaction Graph is generated from ESI. Iterative refinement is done through genetic
algorithm. An initial model of the GUI event interactions and an initial set of test sequences based
on the model are generated. Then a batch of test cases are generated and executed. Code coverage
is determined and unexecutable test cases are identified. Once the infeasible test cases are
identified, it is removed and the model is updated and new batch of test cases are generated and
the steps are followed till all the uncovered ESI relationships are covered. These automated test
case generation process is shown in Figure 3. This automated test generation also provides
validation for GUIs.
The disadvantages are event contexts are not incorporated and need coverage and test adequacy
criteria to check how these impacts fault detection.
Figure 3. Automated Test Case Generation
3. REPAIRING TEST SUITES
Si Huang et al [6], proposed a method to repair GUI test suites using Genetic algorithm. New test
cases are generated that are feasible and Genetic algorithm is used to develop test cases that
provide additional test suite coverage by removing infeasible test cases and inserting new feasible
test cases. A framework is used to automatically repair infeasible test cases. A graph model such
as EFG, EIG, ESIG and the ripped GUI structure are used as input. The main controller passes
these inputs to the test case assembler which then passes the ESIG model to the covering array
generator along with the strength of testing. This covering array generator generates an initial set
of event sequences. The covering array information is send to test case assembler and it assembles
this into concrete test cases. These are passed back to the controller and test suite repair phase
begins. Feasible test cases are returned by the framework once the repair phase is complete.
Genetic algorithm is used as a repair algorithm. An initial set of test cases are executed and if
there is no infeasible test cases, it exits and is done. If infeasible test cases are present, it then
begins the repair phase. A certain number of iterations are set based on an estimate of how large
the repaired test suite will be allowed to grow and for each iteration the genetic algorithm is
executed. The algorithm adds best test case to the final test suites. Stopping criteria’s are used to
stop the iterations.
The advantages are it generates smaller test suites with better coverage on the longer test
sequences. It provides feasible test cases. But it is not scalable for larger applications as execution
time is high. As GUI ripping is used, the programs that contain event dependencies may not be
discovered.
4. GUI TESTING ON VARIOUS APPLICATIONS
4.1. Industrial Graphical User Interface Systems
Penelope Brooks et al [7], developed GUI testing methods that are relevant to industry
applications that improve the overall quality of GUI testing by characterizing GUI systems using
data collected from defects detected to assist testers and researchers in developing more effective
test strategies. In this method, defects are classified based on beizer’s defect taxonomy. Eight
levels of categories are present each describing specific defects such as functional defects,
functionality as implemented, structural defects, data defects, implementation defects, integration
defects, system defects and test defects. The categories can be modified and added according to
the need. If any failures occur, it is analyzed under which defect category it comes and this
classification is used to design better test oracle to detect such failures, better test case algorithm
may be designed and better fault seeding models may be designed.
Goal Question Metric (GQM) Paradigm is used. It is used to analyze the test cases, defects and
source metrics from the tester / researcher point of view in the context of industry-developed GUI
software. The limitations are, the GUI systems are characterized based on system events only.
User Interactions are not included.
4.2. Community-Driven Open Source GUI Applications
Qing Xie and Atif M. Memon [8], presented a new approach for continuous integration testing of
web-based community-driven GUI-based Open Source Software(OSS).As in OSS many
developers are involved and make changes to the code through WWW, it is prone to more defects
and the changes keep on occurring. Therefore three nested techniques or three concentric loops
are used to automate model-based testing of evolving GUI-based OSS. Crash testing is the
innermost technique operates on each code check-in of the GUI software and it is executed
frequently with an automated GUI testing intervention and performs quickly also. It reports the
software crashes back to the developer who checked in the code. Smoke testing is the second
technique operates on each day's GUI build and performs functional reference testing of the
newly integrated version of the GUI, using the previously tested version as a baseline.
Comprehensive Testing is the outermost third technique conducts detailed comprehensive GUI
integration testing of a major GUI release and it is executed after a major version of GUI is
available. Problems are reported to all the developers who are part of the development of the
particular version.
These concentric loops provide resource utilization, errors are caught earlier by inner loops. The
flaws that persist across multiple versions GUI-based OSS are detected by this approach fully
automatically. It provides feedback. The limitation is that the interactions between the three loops
are not defined.
4.3. Continuously Evolving GUI-Based Software Applications
Qing Xie and Atif M. Memon [9], developed a quality assurance mechanism to manage the
quality of continuously evolving software by Presenting a new type of GUI testing, called crash
testing to help rapidly test the GUI as it evolves. Two levels of crash testing is being described:
immediate feedback-based crash testing in which a developer indicates that a GUI bug was fixed
in response to a previously reported crash; only the select crash test cases are re run and the
developer is notified of the results in a matter of seconds. If any code changes occur, new crash
test cases are generated and executed on the GUI. Test cases are generated that can be generated
and executed quickly and cover all GUI functionalities. Once EIG is obtained, a boolean flag is
associated with each edge in the graph. During crash testing, once test cases that cover that
particular edge are generated, then the flag is set. If any changes occur, boolean flag for each edge
is retained. Test cases are executed and crashes during test execution are used to identify serious
problems in the software. The crash testing process is shown in Figure 4. The effectiveness of
crash test is known by the total number o
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