Difference between Unit Testing and Integration Testing

Unit Testing: Unit Testing is a type of software testing where individual software components are tested. Unit Testing of the software product is carried out during the development of an application. An individual component may be either an individual function or a procedure. Unit Testing is typically performed by the developer. It is a testing method using which every independent module are tested to determine if there is any issue by the developer himself.

Integration Testing: Integration testing is the process of testing the interface between two software units or modules. Its focus is on determining the correctness of the interface. Integration testing aims to expose faults in the interaction between integrated units. Once all the modules have been unit tested, integration testing is performed. 

Difference between Unit and Integration Testing:

S. No.	Unit Testing	Integration Testing
1.	In unit testing, each module of the software is tested separately.	In integration testing, all modules of the software are tested combined.
2.	In unit testing tester knows the internal design of the software.	Integration testing doesn’t know the internal design of the software.
3.	Unit testing is performed first of all testing processes.	Integration testing is performed after unit testing and before system testing.
4.	Unit testing is white box testing.	Integration testing is black box testing.
5.	Unit testing is performed by the developer.	Integration testing is performed by the tester.
6.	Detection of defects in unit testing is easy.	Detection of defects in integration testing is difficult.
7.	It tests parts of the project without waiting for others to be completed.	It tests only after the completion of all parts.
8.	Unit testing is less costly.	Integration testing is more costly.
9.	Unit testing is responsible to observe only the functionality of the individual units.	Error detection takes place when modules are integrated to create an overall system.
10.	Module specification is done initially.	Interface specification is done initially.
11.	The proper working of your code with the external dependencies is not ensured by unit testing.	The proper working of your code with the external dependencies is ensured by integration testing.
12.	Maintenance is cost effective.	Maintenance is expensive.
13.	Fast execution as compared to integration testing.	Its speed is slow because of the integration of modules.
14.	Unit testing results in in-depth exposure to the code.	Integration testing results in the integration structure’s detailed visibility.