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Software Testing: Practical

This page describes the practical for the Informatics Software Testing course. It will be marked out of 100 points, and is worth 25% of the assessment of the course. This practical will be undertaken in groups, normally of four (or possibly five), and will be assessed on a group report and individual submissions. This practical should take approximately 20 hours of work from each participant to complete. If at any time you believe you are likely to exceed this estimate by more than 30% please get in touch with me (soa@staffmail.ed.ac.uk) to discuss what can be done.

Deadline

The submission deadline for the practical is: Thursday, 16:00, 20 March 2014 (week 9 if we do not count Innovative Learning Week)

The penalty for late submission follows the uniform policy described in the UG3 course guide. Please read that page, and pay particular attention to the section on plagiarism.

Organisation

For this practical you will be split up, where possible, in groups of 4 or 3. There are 7 tasks which, depending on the size of your group, you will approach as a group or individually as follows:

• In four or five person groups tasks 1-3 should be done as a group activity. Each group member should then choose one of the other four tasks to tackle individually (in five-person groups one of the individual tasks will thus be done twice).

Each of the first three tasks will count 25% of the final assessment (so the group activity counts 75% of the assessment) and each of the individual tasks will count 25% so each member of the group will be allocated the group score on the group tasks plus their individual score on the task they tackled individually.

Deliverables

The overall goal of this project is to produce a short report on the testing of a small system. The report should be at most around 20 pages in length, supported by various other technical deliverables (code for tests). It should be split up into a main body and appendices (the number of pages being counted in the total of 20). The main body of the report should consist of an introduction followed by sections describing the results of the group and individual tasks. You should clearly label each individual section with the author's student number so marks can be allocated to the correct individual. The appendices should include numbered screenshots, figures (e.g. a control flow graph) and any small piece of code you would like to refer to from the explanations, and should constitute visual aids to your explanations from the main body of the report. Appendices should be referred to and explained from the main body of the report - any which are not will not be counted towards your final assessment.

You should be able to complete the tasks described below with around 15-20 hours of effort per group member so each group has a "budget" of 60-100 hours of effort depending on the size of group and your choice. You should consciously manage that effort.

Background

In this practical you will consider the testing of a part of an educational software system that is reasonably mature and has been developed for use by students. The system is called VMAP (follow this link for an intro)and is intended to help users create “mindmaps”. For more explanation of what the system does see the introduction and help on the web page. There is also a link on the VMAP page that allows you to run VMAP from your web browser. The system is now quite old and exhibits some aspects of legacy code.

Resources

The sourcecode is available locally as a tar file compressed using gzip. Please download it from here (and NOT from the project page) and extract it with tar -xzf vmap-0.91.tar.gz or whatever tool you normally use.

Note that, because VMAP is a legacy system written for Java 1.4 it uses variable names that are incompatible with later versions of Java. You have two options to cope with this:

• Set your build environment accordingly: If you're using Ant directly, you can edit the javac rule in build.xml to include source="1.4". If you're using Eclipse, you need to make the same change in the configuration.
• For this assignment, you only need a small piece of the VMAP source, so you could just isolate that small piece and work with it in isolation.

Tools

You can choose either to use the Eclipse IDE or just to use JUnit and other tools on their own; I have no strong preference - you may find some of the tools available in Eclipse useful. You will need some of the following:

1. If necessary you can download JUnit from here. If you are using Eclipse it is probably already installed in the IDE. This article is a reasonable introduction to using JUnit with Eclipse, but bear in mind its age: in particular it's focused on JUnit 3. Here's a good introduction to JUnit 4 (free registration required).
2. You will need some kind of coverage analysis tool:
   • In Eclipse you can use EclEmma. It's easy to install through Eclipse's built in software update mechanism.
   • For stand-alone coverage you should consider something like Cobertura.
   • A review of other OpenSource code coverage tools for Java is available here

Each of the group tasks has an associated tutorial which will help you prepare for it. Please consult the tutorial guidelines and arrange for your tutorials. Good planning and organisation will be necessary- the earlier you do the four tutorials the more time you will have to improve your work on the tasks before the practical deadline!

Now you should work through the following activities:

Task 0: Setting Up (1 hr, no credit)

Preparation: You should have a look at the preparatory activity 1 which covers basic material on the use of Junit. You should also have a look at the preparatory activity 2 which provides an overview of what you will work on in the first couple of tasks in the practical.

You should spend some time looking at the VMAP web page, and should consider what you need to download and begin to set up the environment to support you in the tasks given below.

You should also read all of this Practical specification and create a plan that specifies at least:

1. The allocation of individuals to the individual tasks, i.e. for each of task 4-8 a single individual should be allocated to the task.
2. When and how much effort you are planning to devote to each of the tasks. This can be in any form you like but it should be shared by the entire group and should be easy to change. Remember that not everyone needs to work on all tasks so you might allocate two people to one group task and three to the other two group tasks (this might reduce communication overhead...).

Deliverables: The plan and allocation of tasks - this should be an internal document, shared and evolved by the group (not to be submitted with the practical).

Task 1: Category-Partition Testing (25 marks, group activity)

Preparation: You should thoroughly read and understand section 11.2 of Pezze and Young and the defining paper on the Category Partition method by Ostrand and Balcer, then get together with your group and do tutorial 1.

Tutorial: Contact the tutor (Stuart Anderson) for this session to arrange a tutorial meeting as indicated in the tutorial guidelines

In this task you will generate a test suite in JUnit by first constructing test case specifications using the category partition approach. In this task you will test the method String toRelativeURL(URL base, URL target) that can be found in the file vmap-0.91/vmap/main/Tools.java. You should document the following parts of the process:

1. Provide a short specification of the function you are testing by first having a quick look at the function's comments to understand the problem that it intends to address and then documenting from online, from reliable sources (e.g. RFCs), how this problem is normally addressed. Your specification should include a statement about what the method should do, a definition of its parameters and description of their components, a description of how the method should behave depending on its parameters in all of the cases with examples.
2. Provide a brief summary of what you think the ITFs are for this function outlining why you think they are independent. You need only test one ITF for this practical. Make it clear what ITF you are testing. The chosen ITF should be the primary function of the method.
3. Outline the parameters and environment elements you have identified that are relevant to the method. Explain why you are considering each environment element and, in case you dismiss any environment elements, why this is reasonable (try to avoid explanations such as "lack of time to consider more").
4. Identify the characteristics (categories) of the parameters and environment elements which are relevant for testing and why.
5. Identify partitions (choices in Ostrand and Balcer) and value classes for the characteristics (see below for an explanation of the difference between partitions and value classes).
6. Provide a calculation of the initial number of tests.
7. Decide on any constraints on combinations of the value classes you have identified and mark them by using the notation described in the reading. Here you should attempt to eliminate as many combinations of value classes that could not occur together in test situations as possible.
8. Provide a new detailed calculation of the number of tests reached after introducing the constraints. Your result should not exceed 20 tests.
9. Outline the test case specification you have arrived at, in the form used in your reading and tutorial.
10. Outline the actual tests you have chosen (actual values for the specification from the previous point).

You should then implement your test case specification and test the code for the function. In giving a grade for this part of the practical I will take account of the performance of your test set on a collection of variants of the method.

Deliverables:

1. A section in your report containing your rationale for the tests (the response to the points from above).
2. A screenshot in appendices with the results of running the tests.
3. A file Task1.java that contains the JUnit tests.

Task 2: Coverage Analysis (25 marks, group activity)

Preparation: You should read Pezze and Young chapter 12 and then do tutorial 2 on this topic before arranging your meeting with the tutor.

Tutorial: Contact the tutor (Donal Stewart) for this session to arrange a tutorial meeting as indicated in the tutorial guidelines

Using some appropriate coverage tool (please specify which), assess the level of statement coverage achieved by your test suite. Then do the following:

1. Draw a control flow graph for the method (if you use an automatically generated one, it should be readable not just a jumble).
2. If the statement coverage is below 90%, explain why this is the case with the aid of the control flow graph
3. If you feel that the level of statement coverage can be improved, attempt using the control flow graph to define and implement some additional tests that will increase the level of coverage. Reassess the coverage you achieve and compare it with the coverage achieved before you began this exercise.
4. Write a short evaluation of the adequacy of statement coverage as a measure of the adequacy of the test set for this code. Please be specific to the code by giving examples of covered/uncovered cases for the given problem to support your statements. Refer to the control flow graph where useful.
5. Using the control flow graph and examples for the given problem, provide a short written evaluation of at least one other coverage criterion as a way of evaluating the adequacy of your test set. Include in this at least one test case specification (not necessarily the actual test) that this new coverage criterion might suggest you need to include in your test set.

Deliverables:

1. A section in your report containing your response to the points from above.
2. Screenshots in appendices showing the different levels of coverage you achieved and the figure of the control flow graph.
3. A file named Task2.java containing any new tests.

Task 3: Mutation-based Test Adequacy (25 marks, group activity)

Preparation: Read Pezze and Young Chapter 10 on Adequacy and then do tutorial 3 which covers mutation. This should help to decide how to generate mutants.

Tutorial: Contact the tutor (Hadi Daneshvar) for this session to arrange a tutorial meeting as indicated in the tutorial guidelines

In this section you should consider using mutations to check the adequacy of your test set developed under Task 1. You should do the following:

1. Develop several erroneous variants (or “mutations”) of the toRelativeURL method.
2. Document your chosen types of mutation for each variant.
3. Explain why your test set discovers or fails to discover each mutant.
4. Consider the set of mutants your Task 1 test set fails to discover:
   1. If there are no such mutants, can you design a mutant that is not discovered by your test set? If you think it is impossible to design sucha mutant provide an argument for this. The argument should be as strong as you can make it.
   2. If you have a mutants that are undiscovered by your test set, can you strengthen the test set to capture all of them. Notice that some variants of a function do not result in changes of behaviour of the system, even though the code is different.
5. Augument your test set developed in Task 1 to discover as many of the mutants you developed as possible.

Deliverables:

1. A number of variants of toRelativeURL, call the variant files toRelativeURLVar1.java, toRelativeURLVar2.java, and so on.
2. A short section in the report on the adequacy of your test set as assessed by mutation testing. This might include an argument that your code will discover all mutations where a single mutation operation is carried out.
3. You should include a file with an augumented test suite that catches some of the initially undetected mutants. This could be called Task1-strong.java or something similar.
4. Screenshots in appendices showing how your tests catch/do not catch the mutations.

Task 4: Integration Testing and Coupling-based Coverage (25 Marks, individual activity)

Preparation: You should review the slides for lecture 10 and the slides for Chapters 15 and 21 of Pezze and Young. Have look at tutorial 4.

In this section you will assess the effort required to test the integration of a relatively modest system. Assessing the integration of a system like VMAP can be very time consuming. So, since this is an individual task, you are being asked to write a report rather than doing the testing.

Inspect the code for the classes Vmap, Tools and Controller and the coverage attained by your test suite. Write a short report that:

1. Identifies the main ways in which these three classes are coupled. For example, what methods are called, are there shared variables, …
2. Discusses what would be necessary in a test suite to achieve full statement coverage of the code in these three classes. Please provide examples to support your statements.
3. Outlines what would be necessary to meet the coupling-based coverage criteria for these three classes.

Deliverables:

1. A section in your report, labelled individually, exploring coupling between the specified classes.

Task 5: Using Coupling-based Coverage (25 Marks, individual activity)

Preparation:To prepare for this task you should review the slides for lectures 7 and 8, the slides for chapters 6 and 13 of Pezze and work on tutorial 5.

For this section only consider the method openDocument in the Vmap class and the use of the parameter url. You should do the following:

1. Identify all the last defs and first uses of url, concentrating on coupling between the Vmap and Tools classes.

   Note that in the tutorial we look at coupling through return values as well; that's not necessary here.

2. Work out the coupling paths that must be followed if the test is to conform to the all-coupling-uses coverage criterion. In describing the paths it is probably easiest to label the lines of code (e.g. by numbering them and then describe the pat as a sequence of line numbers in the different functions).
3. Estimate how many different tests you would require to develop an adequate test set to cover your coupling paths.

Deliverables:

1. An, individually labelled, section in your report annotating the source of the relevant methods with first use and last defs for the variable url and identifying the coupling paths.
2. Your report should also estimate the number of tests required to cover all the paths you have identified.
3. If you believe coverage cannot be achieved you should provide an explanation in your report detailing why the coupling-based coverage cannot be met.

Task 6: System Testing (25 marks, individual activity)

Preparation: Re-read the lecture slides that list some of the varieties of testing you might apply during system testing.

Select the three different kinds of system test you consider most appropriate for VMAP. Investigate the best approaches to carrying out these tests on the VMAP system.

Deliverables: A short, individually labelled, section in your report detailing your choice of the three most appropriate system testing activities, together with a justification for this choice. For each of the chosen system testing activities, provide a brief outline of how you would go about such testing for the VMAP system. Try to be reasonably specific, providing examples of test input and identifying what they are intended to test.

Task 7: GUI Testing (25 marks, individual activity)

Preparation: One important aspect of system testing for VMAP is the testing of the GUI used to develop the mind maps. Prepare to answer this question by reading Coverage Criteria for GUI Testing and some more pragmatic advice on the use of the Abbot tool in GUI testing. You might also find this checklist useful.

For this task, you should prepare a short report outlining the key elements in the VMAP GUI that require test and for each of these elements you should outline how you would test that element. A description of the approach should include the description of any necessary scaffolding code, the kind of test to be applied and the expected result.

Note that you are not being asked to carry out this testing work. Your deliverable is a report outlining the testing that is needed for the VMAP GUI.

Deliverables: A short section in your report outlining how to go about testing the GUI provided in VMAP.

Task 8: Project Review (20 Marks, individual activity)

The final task is a review of the main activities of the group in completing the practical. Write a short report on the progress of the group. Your report should include:

1. The group's plan for the tasks.
2. A review of deviations from the plan in terms of time allocation, degree of completion, sequence, completion dates, ...
3. A short summary of what you see as the successes of the group in project planning and execution.
4. A short list of three or four areas you see room for improvement and suggestions of how you might improve in these areas.

Deliverables: A section in your report providing a review of the planning of your group's practical work.

Submission of the Practical Work

After completing the practical you should have the main report and additiona files of tests etc. It will help me with marking if you please exactly adhere to these names. For other sections if you submit additional files use the naming convention: Taskn-XXX.ttt where $n$ is the task number the file relates to and XXX.ttt is a descriptive name and file extension. (including upper/lower case):

report.pdf

A report comprising the main body with your written answers to the tasks and appendices (at least 5 pages) with screenshots, figures, any small pieces of code. The whole report should not exceed 20 pages.

Task1.java

Your tests for Task 1.

Task2.java

Your tests for Task 2.

To submit your work you should designate one member of the group as a submitter for the group. The report should be clearly labeled with your group number. The submitter will gather together the files you wish to submit, and execute this command (if for any reason you have not produced one of the listed files you should omit it from the submit command). The dots at the end of the command signify all the other relevant files:

submit st 1 report.pdf Task1.java Task2.java ...

Assessment

In Weeks 9 and 10 of semester each group will be invited to give a 30 minute presentation of their results where they will have an opportunity to demonstrate the tests they have generated and receive feedback on their work. Details of the signup process will appear shortly on the web page.

Questions

Here are some relevant questions for task 1 and task 2:

Is it ok to isolate toRelativeURL() from the vmap source, and test it separately?

If it will make things easier for you, then certainly.

What's the difference between a partition and a value class?

They're essentially the same thing (“value class” isn't mentioned in Ostrand & Balcer's original paper), but it might be useful to think of partitions as being slightly higher level verbal descriptions (e.g. “none”, “one”, “several”, and “very many”) corresponding to more technical value classes (e.g. 0, 1, 2-100 and 101+). In a more complex project this distinction would be more useful.

Do we need to include our test results?

Yes. Your test case specification should include the results that you expect (c.f. P&Y p.189, Table 11.2). You should also document the actual results you got. A brief commentary to the effect that all tests are passed, or that failures occur and why, would be helpful in demonstrating that you implemented and executed your specification.

My statement coverage is over 90%. What should I do in Task 2?

I've talked about different coverage criteria, and how they're related, and Ntafos' paper in the reading gives a good overview of this. You've just been working with statement coverage. You should make the case for another coverage criterion, and possibly add one or two test cases to improve your score with that criterion.