typicallya test suite is made by creating subclass of unittest testcasewhere each method that has name beginning with "testis test case if we need any setup to be donewe can do it in method called setup()similarlyfor any cleanup we can implement method called teardown(within the tests there are number of unittest testcase methods that we can make use ofincluding asserttrue()assertequal()assertalmostequal((useful for testing floating-point numbers)assertraises()and many moreincluding many inverses such as assertfalse()assertnotequal()failifequal()failunlessequal()and so on atomic py exercise the unittest module is well documented and has lot of functionalitybut here we will just give flavor of its use by reviewing very simple test suite the example we will use is the solution to one of the exercises given at the end of the exercise was to create an atomic module which could be used as context manager to ensure that either all of set of changes is applied to listsetor dictionary--or none of them are the atomic py module provided as an example solution uses lines of code to implement the atomic classand has about lines of module doctests we will create the test_atomic py module to replace the doctests with unittest tests so that we can then delete the doctests and leave atomic py free of any code except that needed to provide its functionality before diving into writing the test modulewe need to think about what tests are needed we will need to test three different kinds of data typelistssetsand dictionaries for lists we need to test appending and inserting an itemdeleting an itemand changing an item' value for sets we must test adding and discarding an item and for dictionaries we must test inserting an itemchanging an item' valueand deleting an item alsowe must test that in the case of failurenone of the changes are applied structurallytesting the different data types is essentially the sameso we will only write the test cases for testing lists and leave the others as an exercise the test_atomic py module must import both the unittest module and the atomic module that it is designed to test when creating unittest fileswe usually create modules rather than programsand inside each module we define one or more unittest testcase subclasses in the case of the test_atomic py moduleit defines single unittest testcase subclasstestatomic (which we will review shortly)and ends with the following two linesif __name__ ="__main__"unittest main(thanks to these linesthe module can be run stand-alone and of courseit could also be imported and run from another test program--something that makes sense if this is just one test suite among many