Test coverage is a black-box method to testing, whereas code coverage is a white-box approach. Depending on the project's needs and scope, you should select test coverage, code coverage, or both test coverage and code coverage.
When you write tests for your applications, you are basically writing code in order to test your code. Therefore, test coverage is also known as code coverage.
There is no strict definition of what exactly constitutes 100 percent test coverage, but it depends on the type of testing that you do. For example, if you only perform unit tests, then this means that you should be testing each individual component within your application. If you don't cover every single line of code, then you aren't testing all of the possible scenarios within your application.
Code coverage tools measure how much code inside of your application has been executed by one or more tests. These tools can tell you which parts of your application are not being tested at all. This information can help you identify which areas of your application may need additional attention when developing new tests.
Test coverage tools are different from code coverage tools because they provide additional details about the tests that were used during execution. With test coverage tools, you can see which lines of code were executed by which tests.
What exactly is code coverage? The percentage of code covered by automated testing is referred to as code coverage. Code coverage basically determines which statements in a piece of code have been executed and which have not throughout a test run. This loop will run until the coverage reaches a predefined threshold.
Code coverage tools analyze test runs to determine what parts of the program have been executed and what parts have not. They report this information in the form of a graph, showing which lines of code have been executed and which have not. The more lines that are covered, the higher the code coverage value is. A line is any sequence of characters, such as a single statement or a block of code.
There are two types of code coverage: statement coverage and branch coverage. Statement coverage measures only whether each individual statement in your program has been executed. Branch coverage goes one step further by checking if each possible decision point in your code is represented in the test suite. For example, if you had a switch statement, then every option would need to be tested independently. Otherwise, your test wouldn't know what action to take when an invalid choice was made.
The most common type of code coverage is line coverage. Here, each logical line of code in your program has an associated value. If 100% of these values are true, then the line of code has been executed. If some values are false, then the line of code has not been executed.
White Box testing methodologies include statement coverage, branch coverage, and path coverage. Statement Coverage checks to see if every line of code is run at least once. The path coverage technique tests all of the program's pathways. If you often alter the program, you must keep the automation test script up to date. Otherwise, you might miss changes made by your future self.
Statement Coverage looks at how many statements (i.e., lines of code) are executed by the test case. This is different from branch coverage which looks at how many branches (i.e., alternative paths through the code) are taken by the test case. Statement coverage does not require that all possible code paths be tested; rather, it requires that each statement be executed at least once. A simple example would be: given x equals 5, then assert x == 5. This test case will pass even though not all values of x were used during testing.
The most common mistake with statement coverage is not covering all possible code paths. For example, let's say we have the following function that calculates the sum of an integer array:
Int sum(int nums)
Return nums + sum(nums[1:]);
To determine test coverage, follow the methods outlined below:
Summary: For most projects and most coverage measures, code coverage of 70–80 percent is a fair aim for system testing. Use a higher target for projects that are especially designed for high testability or have a high failure cost. Unit testing requires 10–20 percent more code coverage than system testing.
There are two ways to measure the quality of software: by how well it works or by how thoroughly it is tested. Which measurement is more important depends on your perspective. From a business standpoint, being able to show that your product works is better than having to rely on testing to find bugs. From a technical standpoint, finding problems during testing is difficult and expensive. Thus, it's best to reduce the risk of introducing errors through writing good code.
The only way to write bug-free code is to assume that you will not be able to deliver a fully functional product at the end of each development cycle. Therefore, it is essential to include some form of validation in every module of your program. This can be done by using assertion functions or exceptions. They provide quick feedback about whether or not your code is working as expected. Without such checks, it would be impossible to know if errors have been introduced into your program.
It is generally accepted that 90 percent code coverage is necessary to ensure that all possible execution paths through your program have been tested. However, this number is highly dependent on the type of programming project you are working on.