Code Coverage Vs Test Coverage: Comparison 2021



How Code Coverage & Test Coverage are Different?

Software developed is not ready for the market until it is thoroughly tested. As the coding process is done by humans and it is possible that there can be some errors.

And it is very important to detect as many defects as possible existing in the code and the functionality of the software.

The testing process analyses the viability of the software. Code coverage and test coverage are the measurement metrics used to analyse if enough testing is done to assure the quality of the application.

Code coverage and test coverage are sometimes misunderstood with each other. In this article, we will discuss 

  1. What is Code Coverage?
  2. What is Test Coverage
  3. Code Coverage vs. Test Coverage

What is Code Coverage?

Code coverage is the measure of the number of lines of code that have been covered by unit tests. Suppose there are 1000 lines of code and 900 lines are tested by performing the unit test on it then the code coverage is 90%.

Code coverage is ensured by performing automated unit tests. Unit tests are a part of Continuous Integration in which the code is tested every time a change is committed in code.

It helps in detecting and fixing the bugs at the same time they are committed and reduces the number of bugs for further testing.

So the more effective the unit test will be the higher will be the code coverage. A quality unit test should check the business logic, the accuracy of the calculated values and the path followed.

Best Practices

  1. Code coverage should be considered as part of the definition. The unit tests should be constantly reviewed to check their effectiveness in the code coverage.
  2. Unit tests should be designed from the beginning of the development process. Test-driven development method will help the development to follow the right path to meet the requirements.

In this method, tests are first written to fail the code and then the code is written in such a way that that it can pass the test.

It will ensure the team that what they have written is functioning right and going to satisfy the requirements.

What is Test Coverage?

Test coverage is very important in the software testing process. It is defined as metrics in software testing that measures the areas of the software are covered by a set of test cases.

Coverage means that ‘what parts of the software are going to be exercised in a global test.?’. In simple words, test coverage measures the effectiveness of the testing.

Suppose a software has 4 features and the testing is performed which interacted and executed only three features then the test coverage will be 75%.

Similarly, if the software has 1000 lines of codes and if only 700 lines are executed in the test cases then the test coverage will be 70%.

By this, we can understand that the effectiveness of testing doesn’t depend upon the number of tests performed on the software but rather on the amount of software is covered during the testing process.

A test case that is covering a large part of the software is more effective than hundreds of test cases written covering only a few sections and not able to execute the rest part. So the value of quality is more in testing than quantity.

Measure Software Tested

It is important to understand that ‘what are the areas or the parts recognised to be considered for getting covered?’.

1. Requirements Coverage

It tells that if the software has been tested against all the user and business requirements.

2. Structure Coverage

It includes the testing of all the design elements in the Software like classes and functions.

3. Implementation Coverage

It measures the number of lines in the code executed in the test cases.

But how to know which requirement has been tested?

Traceability

code coverage vs test coverage

Image Source: Wipro

To trace the testing of any requirement we need to draw a map that shows the trace between each requirement and each test. It will help in recognising which requirements have been tested by a test case and which requirements are not tested at all.

This traceability can be drawn between requirements, design elements, lines of code and test cases.

Test coverage will help in adding necessary test cases and removing unnecessary test cases.

When all the parts of the software are executed and they behave the way they should under different conditions then it ensures that y software is fulfilling the requirements specified at the beginning of the project.

It also ensures that the application is reliable to be used by the customers.

Code Coverage vs Test Coverage

Code CoverageTest Coverage
Code coverage is the measure of the number of application code lines are covered by the tests.It is the measure of the number of functionality tested to ensure the quality of the product including software requirements specifications and other required documents.
To test this generally, selenium framework or any other automated framework is used.It requires manual assistance and cannot completely rely on the automated method of testing.
It improves the effectiveness of test codes and provides you with ways to enhance the performance of coverage.It focuses more on the user’s requirements and the purpose of building the software rather than just the code quality.
It takes less time to implement code coverage tools..It uses the Black Box testing approach, so it has very less interaction with the code and more on the features of the software.
It detects the bugs in the program flow, hence helps in improving the quality of the code.It tests the compliance of the features of the software with the requirements
Only unit tests can be implemented using code coverage tools.Since it’s manual so it is also prone to human judgemental errors.
Requires to implement other types of tests to get a proper look at the quality of the application. 

Image Source: ResearchGate 

Since code coverage is a White Box approach whereas test coverage is a Black Box approach so the tests should be determined based on project specifications.

The current Software industry wants the systematic ways to assure the quality of the product, which includes the efficiency, cleanliness and simplification of the codes written and the ability of the software to satisfy the user’s requirements

Code coverage and test coverage are those systematic metrics that ensure the readiness of the product to get released in the market.