Unit testing vs Integration testing-Difference between Unit testing and Integration testing

This page compares Unit testing vs Integration testing and mentions difference between Unit testing and Integration testing. The other comparison and difference between terms are also mentioned.

In order to enhance quality of software testing, different test methodologies have been implemented across the project. Though unit testing and integration testing is suitable for waterfall type of software model, it can also be applied to other type of software models.

Unit testing

Definition: The testing performed on small piece of code or function or module is known as Unit testing. It is lowest testing level. It helps find bugs at early stage of development and hence avoids bugs at later stages when different modules are combined to have finished product.

It is usually considered to be white box testing where in all the functional details are examined throughly including class, function, interface etc. Unit testing requires knowledge of internals of the software module. Hence unit testing is performed initially by the developer or programmer. At later stages, it can be performed using test cases developed jointly by development team and test team.
Example: Different modules of transmitter are tested separately before being integrated as one transmitter chain.

Integration testing

Definition: The testing performed on combined more than one modules or functions is known as Integration testing. Usually integration testing is conducted after through unit testings have been performed.

It is performed in order to test and verify interfacing between different units/modules. It helps to determine how different units are performing together as a system.

Integration testing is helpful as it uncover about 40% of errors. Integrated system is tested with its counterpart or with other system vendors.
For example: Transmitter chain as a whole is tested and later it has been tested with receiver chain.

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