Test Coverage in Software Testing

What is Test Coverage?

Test coverage is defined as a metric in Software Testing that measures the amount of testing performed by a set of test. It will include gathering information about which parts of a program are executed when running the test suite to determine which branches of conditional statements have been taken.

In simple terms, it is a technique to ensure that your tests are testing your code or how much of your code you exercised by running the test.

What Test Coverage does?

  • Finding the area of a requirement not implemented by a set of test cases
  • Helps to create additional test cases to increase coverage
  • Identifying a quantitative measure of test coverage, which is an indirect method for quality check
  • Identifying meaningless test cases that do not increase coverage

How Test Coverage can be accomplished?

  • Test coverage can be done by exercising the static review techniques like peer reviews, inspections, and walkthrough
  • By transforming the ad-hoc defects into executable test cases
  • At code level or unit test level, test coverage can be achieved by availing the automated code coverage or unit test coverage tools
  • Functional test coverage can be done with the help of proper test management tools

Benefits of Test Coverage in Software Engineering

  • It can assure the quality of the test
  • It can help identify what portions of the code were actually touched for the release or fix
  • It can help to determine the paths in your application that were not tested
  • Prevent Defect leakage
  • Time, scope and cost can be kept under control
  • Defect prevention at an early stage of the project lifecycle
  • It can determine all the decision points and paths used in the application, which allows you to increase test coverage
  • Gaps in requirements, test cases and defects at the unit level and code level can be found in an easy way

What Are Main Differences Between Code Coverage And Test Coverage?

Code coverage and test coverage are measurement techniques which allow you to assess the quality of your application code.

Here, are some critical differences between booths of these coverage methods:

Parameters Code Coverage Test Coverage
Definition Code coverage term used when application code is exercised when an application is running. Test coverage means overall test-plan.
Goal Code coverage metrics can help the team monitor their automated tests. Test coverage is given details about the level to which the written coding of an application has been tested.
Subtypes Code coverage divided with subtypes like statement coverage, condition coverage, Branch coverage, Toogle coverage, FSM coverage. No subtype of Test coverage method.

Test Coverage Formula

To calculate test coverage, you need to follow the below-given steps:

Step 1) The total lines of code in the piece of software quality you are testing

Step 2) The number of lines of code all test cases currently execute

Now, you need to find (X divided by Y) multiplied by 100. The result of this calculation is your test coverage %.

For example:

If the number of lines of code in a system component is 500 and the number of lines executed across all existing test cases is 50, then your test coverage is:

(50 / 500) * 100 = 10%

Examples of Test Coverage

Example 1:

For example, if “knife” is an Item that you want to test. Then you need to focus on checking if it cuts the vegetables or fruits accurately or not. However, there are other aspects to look for like the user should able to handle it comfortably.

Example 2:

For example, if you want to check the notepad application. Then checking it’s essential features is a must thing. However, you need to cover other aspects as notepad application responds expectedly while using other applications, the user understands the use of the application, not crash when the user tries to do something unusual, etc.

Drawbacks of Test Coverage:

  • Most of the tasks in the test coverage are manual as there are no tools to automate. Therefore, it takes lots of effort to analyze the requirements and create test cases.
  • Test coverage allows you to count features and then measure against several tests. However, there is always space for judgment errors.