Unit Testing vs Integration Testing

1. Overview

Integration testing will help to verify the overall system after developing the different modules. When issues observed in the integration test, the unit testing results for specific functionality will help to fix the issue. As a result, both Unit testing and Integration testing are equally important.

2. Comparison

Unit Testing	Integration Testing
Unit testing is a type of testing to check if the small piece of code is doing what it is supposed to do.	Integration testing is a type of testing to check if different pieces of the modules are working together.
Unit testing checks a single component of an application.	The behavior of integration modules is considered in Integration testing.
The scope of Unit testing is narrow, it covers the Unit or small piece of code under test. Therefore while writing a unit test shorter codes have used that target just a single class.	The scope of Integration testing is wide, it covers the whole application under test and it requires much more effort to put together.
Unit tests should have no dependencies on code outside the unit tested.	Integration testing is dependent on other outside systems like databases, hardware allocated for them, etc.
This is the first type of testing is to be carried out in the Software testing life cycle and generally executed by the developer.	This type of testing is carried out after Unit testing and before System testing and executed by the testing team.
Unit testing is not further subdivided into different types.	Integration testing is further divided into different types as follows: Top-down Integration, Bottom-Up Integration and so on.
Unit testing starts with the module specification.	Integration testing starts with the interface specification.
The detailed visibility of the code is coming under Unit testing.	The visibility of the integration structure is coming under Integration testing.
Unit testing mainly focuses on testing the functionality of individual units only and does not uncover the issues arises when different modules are interacting with each other.	Integration testing is to be carried out to discover the issues arise when different modules are interacting with each other to build an overall system.
The goal of Unit testing is to test each unit separately and ensure that each unit is working as expected.	The goal of Integration testing is to test the combined modules together and ensure that every combined module is working as expected.
Unit testing comes under the White-box testing type.	Integration testing is coming under both the Black box and White box type of testing.

3. Reference

https://www.softwaretestingclass.com/what-is-difference-between-unit-testing-and-integration-testing/