Differentiate Between Unit Testing & Integration Testing


Friday November 10, 2017

Delivering an optimum quality product is a tough task as this requires a joint effort and co-operation between different team members. Right from the step of planning the product, to  development and final delivery of the product, each and every step of the development process is crucial and requires one to stay at toes and not at ease.


Sometimes, deciding the most suitable testing for one’s product gets difficult as the market offers a variety of options such as unit tests, integration tests, functional tests, E2E tests, browser tests, etc. therefore, it is important for one to have a clear understanding about different types of testing so that it gets easier to decide the type of testing that would allow one to test a product completely.

Out of these multiple types, two of the most commonly used are unit testing and integration testing.

1) Unit Testing:

  • Tests that are conducted by developers for a particular unit of code such as module or component that has been developed by them
  • One of the most effective and simple way to determine if the individual units of source code that are being tested are perfect and ready to use
  • Helps in cutting down the cost of bug fixes as the bugs are identified during the early stages of software development life cycle (SDLC)

2) Integration Testing:

  • a type of testing that tests a product in terms of the integration between its modules
  • Its one of the most effective software testing techniques in which the individual units of a program are combined and tested as a group
  • Executed with the help of test stubs and test drivers that assist in its easy execution

Difference between Unit Testing and Integration Testing

Both these forms of testing have their own significance but it is important to understand the difference between the two:

  1. Aim

Unit testing tests each part of the program individually so as to ensure that each of them perform correctly. Whereas, integration testing combines the modules and test them as a group for their optimum functionality.

  1. Time of testing

Unit testing is independent and can be performed at any point of SDLC. On the other hand, integration testing is conducted after unit testing is completed and system testing begins.

  1. Sub-divisions

Unit testing cannot be sub-divided whereas integration testing can be divided into top-down integration, bottom-up integration and so on.

  1. Integration errors

Unit testing cannot identify integration errors, or other system-wide errors that exist. Whereas, integration testing can identify all sorts of errors as its purpose is to test and identify errors in modules.

  1. Specification

Unit testing begins with the specification of the modules whereas integration testing begins with interface specification.

  1. Type of testing

Unit testing is a form of white-box testing, which refers to testing of internal structure of a program or application. Whereas, integration testing is both white-box and black box testing.

  1. External dependencies

Unit testing does not examine whether a program code works properly with external dependencies whereas integration testing tests the code on the same parameters.

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  1. Maintenance

Conducted by the software developer oneself, testing a program using unit testing is cheaper as compared to integration testing which is executed by a team of testers.

Unit and Integration Testing are equally important

Both these forms of testing have their own importance as the absence of one might impact the overall performance and development of the product. While unit testing ensures that optimum quality during the development phase of the product, integration testing ensures that there are no errors pending after the development of different modules.

Moreover, identifying the errors during integration testing raises the need of conducting unit testing again so as to identify the specific error in the program. Therefore, to ensure the premium product delivery, it is better and advisable to keep implementing both these forms of testing as and when required.


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