What s the difference between unit tests and integration tests

Question

What s the difference between unit tests and integration tests     Are there different names for these tests  Like some people calling unit tests functional tests  etc

User · Answer

A unit test should have no dependencies on code outside the unit tested. You decide what the unit is by looking for the smallest testable part. Where there are dependencies they should be replaced by false objects. Mocks, stubs .. The tests execution thread starts and ends within the smallest testable unit.

When false objects are replaced by real objects and tests execution thread crosses into other testable units, you have an integration test

User · Answer

A unit test is done in  as far as possible  total isolation   An integration test is done when the tested object or module is working like it should be  with other bits of code

User · Answer

A unit test is a test written by the programmer to verify that a relatively small piece of code is doing what it is intended to do  They are narrow in scope  they should be easy to write and execute  and their effectiveness depends on what the programmer considers to be useful  The tests are intended for the use of the programmer  they are not directly useful to anybody else  though  if they do their job  testers and users downstream should benefit from seeing fewer bugs    Part of being a unit test is the implication that things outside the code under test are mocked or stubbed out  Unit tests shouldn t have dependencies on outside systems  They test internal consistency as opposed to proving that they play nicely with some outside system    An integration test is done to demonstrate that different pieces of the system work together  Integration tests can cover whole applications  and they require much more effort to put together  They usually require resources like database instances and hardware to be allocated for them  The integration tests do a more convincing job of demonstrating the system works  especially to non-programmers  than a set of unit tests can  at least to the extent the integration test environment resembles production   Actually  integration test  gets used for a wide variety of things  from full-on system tests against an environment made to resemble production to any test that uses a resource  like a database or queue  that isn t mocked out  At the lower end of the spectrum an integration test could be a junit test where a repository is exercised against an in-memory database  toward the upper end it could be a system test verifying applications can exchange messages

User · Answer

A unit test tests code that you have complete control over whereas an integration test tests how your code uses or  integrates  with some other code   So you would write unit tests to make sure your own libraries work as intended  and then write integration tests to make sure your code plays nicely with other code you are making use of  for instance a library   Functional tests are related to integration tests  but refer more specifically to tests that test an entire system or application with all of the code running together  almost a super integration test

User · Answer

Unit test is usually done for a single functionality implemented in Software module  The scope of testing is entirely within this SW module  Unit test never fulfils the final functional requirements  It comes under whitebox testing methodology    Whereas Integration test is done to ensure the different SW module implementations  Testing is usually carried out after module level integration is done in SW development   This test will cover the functional requirements but not enough to ensure system validation

[unit-testing] What's the difference between unit tests and integration tests?

Examples related to unit-testing

Examples related to integration-testing