When looking at different ways of testing software, you’ll find that there are software testing methods to suit any application, system or unit of code. Within each of those, there are different techniques that help you make sure you’re being as thorough as needed to get your software passed. Here we look at some of the high-level methods and associated techniques in software testing.
Differences between automated and manual software testing
Before getting into the different software testing methods available, it’s worth looking at the contrasts between automated and manual software testing. As suggested, manual testing is carried out by a person without the aid of any tools. Automated testing may still be carried out by a person but only with the help of scripts, software and more to automate the process.
Some methods are better suited to manual testing, while others are better suited to automated testing. Anything that’s looking at a user experience will be best tested with a manual technique, to understand how users will interact with the software and identify quirks that a creative brain may encounter. Whereas something like load testing, checking how much traffic a website can handle before it begins to struggle is significantly easier to automate. Cost, reliability and more are further factors to consider too.
What is Black Box software testing?
Black Box software testing is a method used when the tester doesn’t know the inner workings of the code or system they’re testing. The idea is that they’re coming into it blind, so what they’re trying to test is ‘hidden’ in a metaphorical black box.
It’s a method that’s used when an application is being tested against what it’s supposed to do. A tester isn’t trying to work through the software designer’s own methods, but is instead approaching the code or system as a user – and therefore pushing its limits to check whether it works as intended or whether it would throw up issues to the person using it.
Black Box software testing techniques
There are a number of well-known Black Box software testing techniques, but one of the more popular is Equivalence Partitioning. This is often one of the first stages, as it is designed to eliminate the need to test a high number of different scenarios or values. Instead, these scenarios are grouped (or partitioned) and tests are designed to pick one scenario from each partition to cover off the different options.
Boundary-value analysis is, in a way, similar to Equivalence Partitioning. It is used when there are data ranges to be tested and works on the idea that there tend to be more errors in software at the extreme ends of an input range. By focussing testing on the boundaries of these data ranges, you’re more likely to uncover errors.
Cause-effect graph testing is where data is shown using a clear graphical representation, which groups cause effects. By finding all the root causes of a particular software effect, it can be easier to identify the main defects that are causing problems, and it’s simple to understand where each of these causes can be grouped.
What is White Box software testing?
Unsurprisingly, White Box software testing methods are the opposite of Black Box. So you’d use White Box methods when you’re examining the inner workings of a piece of software. Straight away, a key difference is that you need to understand programming in order to carry out White Box methods – you aren’t simulating a user experience, you’re looking at the specific code to find errors. While this makes it a more complex method, it does have significant advantages too, including finding hidden defects within the code that would otherwise be missed.
White Box software testing techniques
Control flow testing is one of the more well-used techniques within White Box testing. It involves using the control flow of a piece of software to define the test cases. This means you can be sure every element of the control flow is covered in the testing, so no stone is left unturned when searching for defects.
Data flow testing is similar, in that it works from the control flow, but instead focuses on the data as part of the control flow, and the unreasonable things that can happen to data as part of the flow. The intention of data flow testing is to find data anomalies that can occur and ensure they’re accounted for.
Branch testing and path testing are similar. Branch testing is used when software has various decisions that cause the journey to branch off, with the tests determined to check every branch. Path testing is used more when there are different paths as part of the software, with each path being covered in the test scenarios.
What is Gray Box software testing?
You won’t be surprised to know that Gray Box testing is a mix of both Black and White Box methods. It primarily takes a similar approach to Black Box testing, where the tester is looking at the output of software and not right into the source code, but they have a working knowledge of the processes and can, therefore, create test plans that go deeper than a standard Black Box methodology.
What is Agile software testing?
Quite simply, Agile software development is where a piece of software is changing due to collaborative work between customer and developer as feedback is received. Agile testing methods are therefore those that are included in this structure of workflow – test plans that can debug at various stages of development as the software evolves.
What is ad hoc software testing?
Ad Hoc software testing is the least formal type of testing. It’s essentially a form of error guessing, itself a technique under the Black Box methodology. It’s testing without a plan or documentation, trying things by improvisation to see if an error is produced. While it may be an informal method, it can be effective at finding significant defects.
What method to use
When you’re ready to begin testing something you’ve developed, it’s important you take the time to find the right methodologies that are suited to the code you’ve written. Be comprehensive and use different techniques at different stages to create a test plan that will ensure your software is robust.
Have your own views on the Software Testing Methods we have mentioned? Leave your thoughts in the comments below or if you need expert software testing from ISTQB certified software testers give us a call today on 0800 133 7948.
