Difference Between Unit Testing and Integration Testing

Difference Between Unit Testing and Integration Testing

If we consider the pyramid of testing while developing a software application there are multiple tests that are performed. Unit testing and Integration testing are among the most common and important testing mechanisms. Commonly unit testing and integration testing are linked together. Although these are completely different mechanisms they are interlinked. 

The write-up below defines and explains the major differences between the unit test and integration test. Read on to learn the key features of these testing mechanisms and use them to build a pro application. 

What is Unit Testing? 

Unit testing focuses only on a single module of the code. Usually, this module is isolated from the side effects of other components. The module can be a single component or even an individual procedure to be executed. This makes testing and error detection easier for the particular unit. For advanced processes of development, unit testing plays a crucial role. 

It reduces the cost for bug fixes as these bugs can be identified in the early phase of development. When compared to other tests error detection is easier in unit testing.

Know about white box testing types, tools, and examples.

What is Integration Testing? 

The testing of the interface amongst two modules is tested under integration testing. The prime focus of integration tests is to check the correctness of different integrations. All the errors and faults are detected and fixed at the early stage. Once the individual modules are tested then the integration testing is performed. 

These integration tests can be performed using top to bottom or bottom to top approaches. In integration testing it is not required to mock the individual parts away, complete application is tested at once.

Difference Between Unit Testing and Integration Testing:

Unit Testing Vs Integration Testing:  

Unit Testing

Integration Testing 

As the name signifies the type of testing tests each module of the code and displays the correctness of each of these parts.  In Integration testing, different modules are combined and their integration is tested. 
It is a type of White Box Testing It is a type of Black Box Testing
Unit testing can be carried out at any point of the time. Integration testing is done once unit testing is completed. 
The functioning of each unit is tested and none of the errors in their integration are detected.  The integrations in the entire system are checked through these testing codes. 
Unit testing begins with module specification. It begins with interface specification. 
All the attention is paid to individual modules.  Importance is given to the integration between different modules. 
It does not check that your code is working fine with any of the external dependencies.  Integration tests also verify the correct working of code with any dependencies present externally. 
Unit testing is executed by developers.  Usually, the testing team performs Integration testing.
Error detection is easier. In comparison with unit testing, it is difficult to detect errors. 
Maintaining unit tests is comparatively cheaper.  Integration test maintenance is expensive. 

Key Differences: Unit Vs Integration Testing

  • In the Unit testing each unit of your code is tested individually to ensure that it is ready for use. On the other hand integration amongst different modules can be tested by integration testing. 
  • In Unit testing errors are displayed in each part, whereas all the modules are combined together to check if they are working fine in Integration testing. 
  • The starting of unit testing is by a specification of modules, whereas interface specification is the first step for Integration testing. 
  • Unit tests have no specific timing to be performed i.e can be performed whenever required, whereas the tests of integration must be performed once the unit testing completes.
  • Integration testing can be performed only by the testing team,  whereas unit testing is implemented by developers themselves. 
  • Errors in unit testing can be detected easily when compared to integration testing. 
  • Unit testing is categorized under white box testing and Integration testing is under the black box testing category. 

Also ReadDifference Between White Box and Black Box Testing

Closing Lines:

To have a successful and effective software development both unit and integration testing play an important role. Although the purpose varies they complement one another nicely. Make sure you perform both the tests to have an uninterrupted working of your application. 

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