Test Coverage in Software Testing (Tips to Maximize Testing Coverage)

This article is a complete guide to test coverage in software testing. You will learn how to test more, save time, and achieve better testing results. Let’s get started. 

Software testing is an essential activity in the software development and maintenance life cycles. It is a practice often used to decide and improve software quality.

Nowadays, development has become much more systematic and organizations seek measures of testing completeness and effectiveness to show test completion criteria. Of them all, coverage is considered especially valuable.

What is Test Coverage

Simply put, the test coverage is “What are we testing and how much are we testing?” 

Test coverage helps monitor the quality of testing, and assists testers to create tests that cover areas that are missing or not validated.

Most teams base their coverage calculations on functional requirements alone. It is also fair because first and foremost an application should do what it is supposed to do. If not, its speed, security or ease of use – none of it matters.

However, if dedicated and independent non-functional testing teams are working on performance, security, usability testing, etc., then they will have to track their requirements all the way to execution through test coverage analytics.

Test Coverage and Code Coverage

Test coverage is often confused with Code Coverage. Even though the underlying principles are the same, they are two different things.

Code Coverage really talks about unit testing practices that have to target all areas of the code at least once and is done by developers.

Test Coverage, on the other hand, is testing every requirement at least once and is obviously a QA team activity.

What really qualifies to be a covered requirement depends on the interpretation of each team.

For example, some teams call for a requirement to be covered if there is at least one test case against it. Sometimes, it is covered if at least one team member is assigned to it. Or, if all the test cases associated with it are executed.

• If there are 10 requirements and 100 tests created – when these 100 tests target all of the 10 requirements and don’t leave out any – we call this adequate testing coverage at the design level.
• When only 80 of the created tests are executed and target only 6 of the requirements. We are saying that 4 requirements are not covered even though 80% of testing is done. This is coverage statistics at the execution level.
• When only 90 tests relating to 8 requirements have assigned testers and the rest of them are not, we say the test assignment coverage is 80% (8 out of 10 requirements).

It is also important as to when to calculate coverage.

If you do this too early in the process, you will see a lot of gaps because things are still incomplete. So it is generally advised to wait until the Last Build i.e. Final Regression Build. This will give the correct coverage of the Tests performed for the given Requirements.

Also read => Release and Deployment Management Process.

My Experience

Scene 8 years ago: When I was having 2 years of experience in software testing industry I was thinking that it was alright if I don’t know some fundamentals about software testing as something one can learn with experience and I too will do.

I was right and wrong as well.

Right because with experience, you learn to see a bigger picture, you understand the real meaning of “Critical Situation” and you understand the end user more.

Wrong because none of the mentioned things require experience, but early learning, which I understood very late. That is the encouraging factor to write this post.

Here is my experience from one of the interviews at that time:

How do you make sure that test coverage is complete or maximum? I was asked.

Ummmm……I make sure to test every functionality, I said.

So you are saying that once you test all the functionalities, you feel that you have covered a maximum of application/product, in terms of testing, the interviewer backfired.

Ummm…well….ummm….yes, because when you test all the functionalities, you are confident about application/product’s behaviour, I supported my answer.

I agree, but my question is – will it give you confidence that your testing coverage is maximum or complete? the interviewer was in no mood to let me go.

Now, I was growing impatient, unknown about the fact that I was going to learn one of the most important topics about software testing – “Test coverage”.

Rather than reproducing the excerpts of the interview, I am summarizing here what I learned about Testing Coverage, on that day. But before that, let’s be clear on one point – testing coverage does not ever mean to know whether you are testing enough or not, neither does it mean you are testing perfectly or not.

Test coverage meaning

Testing coverage can have a different meaning in different contexts. Let’s discover those contexts one-by-one:

Product coverage – What aspects of the product did you look at?

Yes, when testing coverage is being measured in terms of product, the main area to focus on is – which areas of the product have you tested and which remain untested?

Example #1

If “knife” is a product, you are testing; just do not concentrate on checking whether it cuts the vegetables/fruits properly. There are other aspects to look for such as – the user should be able to handle it comfortably.

Example #2

If “notepad” is an application you are testing, checking relevant features is a must.

But other aspects to be taken care are – application responds properly while using other applications simultaneously, the application does not crash when the user tries to do something unusual, the user is provided proper warning/error messages, the user is able to understand and use the application easily, help content is available when required.

If you don’t look into the mentioned scenarios, you can’t claim that the testing coverage for the application is complete.

Risk coverage – What risks have you tested for?

Risk coverage is another aspect of having complete testing coverage. You can’t tag the product or application as “tested” until you test the associated risks too. Coverage of associated risks is an important factor in overall testing coverage.

Example #1

While testing an aeroplane, if a tester tells you that he/she has fully tested the internal system of the aeroplane and it’s working fine but only flying capability of the aeroplane was not covered while testing – what would be your reaction?

Well, that is what risk coverage means. Identifying risks as per the application/product and testing it thoroughly is always good practice.

Example #2

While testing an e-commerce site, testers considered every effective factor but did not consider the risk of numbers of users accessing the website simultaneously and on the Super OFFER day, the not considered risk proved to be a huge mistake.

Recommended reading =>

• Risk-based testing
• Risk management in test execution phase

Requirements coverage – What requirements have you tested for?

If a product or application is developed very well but if it’s not matching with customer’s requirements then it’s of no use. Requirement coverage while testing is as important as product coverage.

Example #1

Excited for the family function, you asked the tailor to stitch your dress and put those peacock blue show buttons on the neckline.

While stitching the dress, the tailor thought that putting those buttons on the neckline would not look good so he stitched a golden colored border instead. On the day of the trial, the unhappy customer definitely shouted at the tailor for not sticking to the requirements.

Example #2 

While testing a chat application, tester took care of all the important points like multiple users chatting in a group, two users chatting independently, all types of emoticons available, updates sent to user immediately etc. but forgot to look into the requirement document, which clearly mentioned that when two users chat independently, the video call option should be enabled.

The client marketed the chat application claiming that it would allow calling, while two users chatted independently. You can imagine what would have happened to the chat application.

Also read=> How to Create Requirements Traceability Matrix

How to adopt a proper Test Coverage method

Awareness is everything

First things first, the QA team must know how much work is involved and where the design tasks are at. This way, they are going to be aware if more tests are to be added. To do this, you could use an RTM as is the typical practice.

=> Check this article out to know more about it and how to use it: How to Create Requirements Traceability Matrix – Exact Process with Sample Template

Second, check the resource assignment and test execution process to see if everything is tested in a more effective manner.

A table such as the one below can be helpful

How to make sure everything is tested

• All testers should be aware of the requirements and the testing methods
• Prioritize your Requirements and focus your energy where it is most needed
• Be informed about how a certain release is different from the previous one so you can identify critical requirements more accurately and focus on maximum positive coverage
• Adapt Test Automation
• Use Test Management tools to always stay in the know
• Smart Work Assignment – Channel your best resources towards critical tasks and let new testers explore more for a fresh perspective
• Maintaining a checklist for all tasks and miscellaneous activities
• Interact more with your Dev/Scrum/BA teams to get insights into the application behavior
• Keep track of all your build cycles and fixes
• Identify the most impacting problems in the initial build itself (when possible) so the later ones can work for better stability and reach those areas blocked by prior problems

Critical areas and methods for effective testing

#1) Resource jumbling: Exchange tasks between your team members. This helps improve engagement and prevent knowledge concentration.

#2) Compatibility coverage: Make sure you are aware and include different browsers and platforms to test your application.

#3) Ownership: Make testers accountable and give them free rein (with monitoring and support of course) for the module/task that they are working on. This helps build responsibility and lets them try creative ways instead of following the beat down the road.

#4) Deadlines: Knowing the release deadlines prior to the commencement of the testing phase helps with effective planning

#5) Communication: Stay in touch with devs and other teams in between release cycles to see what’s going on.

#6) Maintain an RTM: Acts as a good derivative to the Stakeholders or Clients, based on which the release schedule can be confirmed.

Advantages of Testing Coverage Awareness for a Tester

• It primarily helps with testing tasks prioritizing
• It helps achieve 100% requirement coverage or in other words, it prevents requirement leakage
• Impact Analysis becomes easier
• Useful in determining the EXIT criteria
• Enables test leads to prepare clear test closure report

Conclusion

Test coverage does not end in the mentioned context. There are many other points that should be considered when it comes to testing coverage.

It is not always true that when you test more, the results are better. In fact, when you test more with no apparent strategy, you probably will end up investing a lot of time.

With a more structured approach, an aim at 100% requirement coverage and effective testing methods, you will not compromise on quality.

We hope the techniques outlined in this article will give you some good pointers.

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