自上而下和自下而上的集成测试之间的区别

先决条件–集成测试

1.自上而下的集成测试：
自上而下的集成测试，也称为增量集成测试。在这种“自顶向下”方法中，首先测试更高级别的模块，然后再测试更高级别的模块和更低级别的模块。然后，这些模块将进行相应的集成。此处，较高级别的模块是指主模块，较低级别的模块是指子模块。此方法使用Stub，这些Stub主要用于模拟子模块，如果未开发被调用的子模块，则此Stub可以作为瞬时替换。

2.自下而上的集成测试：
自下而上的集成测试是集成测试的另一种方法。在这种自下而上的方法中，首先测试较低级别的模块，然后再测试较低级别的模块和较高级别的模块。然后，这些模块将进行相应的集成。此处，较低级别的模块是指子模块，较高级别的模块是指主模块。这种方法使用测试驱动程序，该驱动程序主要用于初始化所需的数据并将所需的数据传递到子模块，如果需要，则从较高级别的模块传递到较低级别的模块。

下图表示自上而下和自下而上的集成测试方法。

自上而下的集成测试和自下而上的集成测试之间的区别：

S.No.	TOP DOWN INTEGRATION TESTING	BOTTOM UP INTEGRATION TESTING
01.	Top Down Integration testing is one of the approach of Integration testing in which integration testing takes place from top to bottom means system integration begins with top level modules.	Bottom Up Integration testing is one of the approach of Integration testing in which integration testing takes place from bottom to top means system integration begins with lowest level modules.
02.	In this testing the higher level modules are tested first then the lower level modules are tested and then the modules are integrated accordingly.	In this testing the lower level modules are tested first then the higher level modules are tested and then the modules are integrated accordingly.
03.	In this testing stubs are used for simulate the submodule if the invoked submodule is not developed means Stub works as a momentary replacement.	In this testing drivers are used for simulate the main module if the main module is not developed means Driver works as a momentary replacement.
04.	Top Down Integration testing approach is beneficial if the significant defect occurs toward the top of the program.	Bottom Up Integration testing approach is beneficial if the crucial flaws encounters towards the bottom of the program.
05.	In Top Down Integration testing approach the main module is designed at first then the submodules/subroutines are called from it.	In Bottom Up Integration testing approach different modules are created first then these modules are integrated with the main function.
06.	It is implemented on Structure/procedure-oriented programming languages.	It is implemented on Object-oriented programming languages.
07.	The complexity of this testing is simple.	The complexity of this testing is complex and highly data intensive.
08.	It works on big to small components.	It works on small to big components.
09.	In this approach Stub modules must be produced.	In this approach Driver modules must be produced.