What is a test case?

(software testing)What is a test case?
Test cases is a sequence of steps to test the correct behavior of a functionality/feature of an applicationWhat is a test case?
Us programmers write code. Software testers must test each case. Programmers don't always get everything right. Sometimes is something changes in one part of the code something else breaks in another part of the code. It is necessary to test each possible case.





The tester must test each possible condition and make sure it matches the expected result.
Those answers speak in terms of software, which is correct....





HOWEVER, in another context, a test case may be a legal one:





A legal action whose outcome is likely to set a precedent or


test the constitutionality of a statute
In software engineering, a test case is a set of conditions or variables under which a tester will determine if a requirement upon an application is partially or fully satisfied. It may take many test cases to determine that a requirement is fully satisfied. In order to fully test that all the requirements of an application are met, there must be at least one test case for each requirement unless a requirement has sub requirements. In that situation, each sub requirement must have at least one test case. Some methodologies like RUP recommend creating at least two test cases for each requirement. One of them should perform positive testing of requirement and other should perform negative testing.





If the application is created without formal requirements, then test cases are written based on the accepted normal operation of programs of a similar class.





What characterises a formal, written test case is that there is a known input and an expected output, which is worked out before the test is executed. The known input should test a precondition and the expected output should test a postcondition.





Under special circumstances, there could be a need to run the test, produce results, and then a team of experts would evaluate if the results can be considered as a pass. This happens often on new products' performance number determination. The first test is taken as the base line for subsequent test / product release cycles.





Written test cases include a description of the functionality to be tested taken from either the requirements or use cases, and the preparation required to ensure that the test can be conducted.





Written test cases are usually collected into Test suites.





A variation of test cases are most commonly used in acceptance testing. Acceptance testing is done by a group of end-users or clients of the system to ensure the developed system meets their requirements. User acceptance testing is usually differentiated by the inclusion of happy path or positive test cases.

















[edit] Structure of test case


Formal, written test cases consist of three main parts with subsections:





Introduction/overview contains general information about Test case.


Identifier is unique identifier of test case for further references, for example, while describing found defect.


Test case owner/creator is name of tester or test designer, who created test or is responsible for its development


Version of current Test case definition


Name of test case should be human-oriented title which allows to quickly understand test case purpose and scope.


Identifier of requirement which is covered by test case. Also here could be identifier of use case or functional specification item.


Purpose contains short description of test purpose, what functionality it checks.


Dependencies


Test case activity


Testing environment/configuration contains information about configuration of hardware or software which must be met while executing test case


Initialization describes actions, which must be performed before test case execution is started. For example, we should open some file.


Finalization describes actions to be done after test case is performed. For example if test case crashes database, tester should restore it before other test cases will be performed.


Actions step by step to be done to complete test.


Input data description


Results


Expected results contains description of what tester should see after all test steps has been completed


Actual results contains a brief description of what the tester saw after the test steps has been completed. This is often replaced with a Pass/Fail. Quite often if a test case fails, reference to the defect involved should be listed in this column.