First, let’s try to understand what is covered by the Code.
It is a kind of metric intended to measure the testing effort applied to the software application.
Its goal is to inspect the code directly and is therefore a form of white box testing.
How do we capture code coverage metrics?
The process involves the instrumentation of the program and the execution of the tests. In this way we can identify the code that has been executed and the one that has been omitted. We can see that unit testing and code coverage are complementary to each other. Unit tests confirm the compliance of the program’s performance with respect to the requirements, while code coverage reveals the areas that are left out of the tests.
The software development process aims to have a measurement of coverage through the definition of the number of branches or declarations covered by the test. Even after having full branch coverage or statement coverage, there’s no assurance that there aren’t some key bugs in the code. So 100% branch coverage or statement coverage is still pretty illusory and doesn’t provide any guarantee of perfection for both developers and managers.
Now the key point of contention remains that having full coverage is still inadequate. The reason why branch coverage and statement coverage do not provide any confirmation of code logic execution. Both branch coverage and statement coverage are useful for identifying important problems in the part of the code that did not execute.
However, the path coverage technique is comparatively much more robust and helps us to reveal the defects during the early stages. Before we dive into path coverage, let’s discuss some of the drawbacks of branch coverage and statement coverage techniques.
Statement Coverage:
The main benefit of statement coverage is that it is able to largely isolate the part of the code that could not be executed. The statement coverage criteria require having an adequate number of test cases for the program to ensure the execution of each statement at least once. Despite achieving 100% claim coverage, there are most likely many uncaught errors.
Therefore, s coverage reporting indicating 100% statement coverage will induce the manager to be happy with the false temptation to end up with more testing, which may lead to the release of faulty code into production. mass. So we can’t see enough 100% statement coverage to create a reasonable amount of confidence in perfect application behavior.
Since 100% statement coverage tends to be expensive, the developers chose a better testing technique called branch coverage.
Branch Coverage or Decision Coverage:
Branch coverage is more impressive as it tends to dig deeper into the code compared to the statement coverage technique. Branch coverage is a metric for measuring the results of testable decisions. The branch coverage criteria call for having an adequate number of test cases for each program to ensure that each decision or branch is executed at least once. For most products, branch coverage is considered the minimum coverage. Therefore, this is better than statement coverage, although it is not suitable for applications that need higher integrity.
It’s easy to determine how many branches a method will have. The simple method of calculating the decision results, a method you can have, is to count the number of branches expected to be covered along with adding one more input branch.
It has been seen that even 100% account statement coverage, as well as branch coverage, is not enough. Also, for complex methods, it is practically not feasible to test each and every path. This necessitates the need for a better test alternative, ie base path coverage.
Basic route coverage:
A route is nothing more than the way execution proceeds through a method from start to finish. The routes, which are independent, are also known as basic sets. In other words, the base set is the smallest group of paths grouped together to form all possible combinations of paths through the method.
The route coverage criteria call for having an adequate number of test cases for each feasible route, base routes to ensure execution of each route at least once in the program segment.
If there are, say, N number of decisions in a method, then it could have 2^N number of paths. However, in the case where a method has a loop, the number of routes can become infinite. Due to the extremely large number of routes in the app, route coverage also tends to be difficult. To reduce the number of paths for the test, we can take the help of the metric known as Cyclomatic Complexity. The question of how much path coverage is needed is answered based on the complexity or risk factor involved in the application under test.
Basic path coverage is similar to branch coverage in that it guarantees testing/execution of every decision result. There is still a point of difference compared to branch coverage in the way that each decision result is tested independently of each other. It involves reversing the decision executed just before it, leaving the remaining executed branches intact. Since basic routing coverage addresses all statements as well as branches throughout a method, it is an effective substitute for branch coverage and statement coverage. This is the reason why basic path coverage is considered much more robust compared to branch coverage.
How to create data for tests:
In simple examples, it can be easy to achieve full coverage of the basic path, while in real world scenarios, full testing of the basic paths becomes extremely challenging, and may even be impossible. One of the reasons for this is the need to have test data, which should be able to execute a particular route by testing the interaction between various decisions through a method. It is not a simple process to enter some data that could lead to the execution of a particular route.
However, following coding best practices can be helpful in simplifying the testing process.
1) Keep your code simple.
2) Try not to use methods that have a cyclomatic complexity greater than ten.
3) Not having more roads based on number.
4) Have less number of decisions for each path.
5) Do not have duplicate decisions.
6) Try not to have data dependency
Conclution:
Statement coverage as well as branch coverage criteria, while simple to execute, have the drawback that some of the major flaws tend to go unnoticed, so project managers, developers, and testers can draw erratic conclusions. of perfection, while the fact could be something else
While basic path coverage is a more robust approach that can identify defects that might otherwise have gone unnoticed.