Saturday, April 11, 2009

Explain Software Testing Life Cycle (STLC).

Software testing life cycle identifies what test activities to carry out and when (what is the best time) to accomplish those test activities. Even though testing differs between organizations, there is a testing life cycle.


Software Testing Life Cycle consists of six (generic) phases:

Software Testing Life Cycle Test Planning,
Software Testing Life Cycle Test Analysis,
Software Testing Life Cycle Test Design,
Software Testing Life Cycle Construction and verification,
Software Testing Life Cycle Testing Cycles,
Software Testing Life Cycle Final Testing and Implementation and
Software Testing Life Cycle Post Implementation.

Software testing has its own life cycle that intersects with every stage of the SDLC. The basic requirements in software testing life cycle is to control/deal with software testing – Manual, Automated and Performance.

Test Planning

This is the phase where Project Manager has to decide what things need to be tested, do I have the appropriate budget etc. Naturally proper planning at this stage would greatly reduce the risk of low quality software. This planning will be an ongoing process with no end point.

Activities at this stage would include preparation of high level test plan-(according to IEEE test plan template The Software Test Plan (STP) is designed to prescribe the scope, approach, resources, and schedule of all testing activities. The plan must identify the items to be tested, the features to be tested, the types of testing to be performed, the personnel responsible for testing, the resources and schedule required to complete testing, and the risks associated with the plan.). Almost all of the activities done during this stage are included in this software test plan and revolve around a test plan.

Test Analysis

Once test plan is made and decided upon, next step is to delve little more into the project and decide what types of testing should be carried out at different stages of SDLC, do we need or plan to automate, if yes then when the appropriate time to automate is, what type of specific documentation I need for testing.

Proper and regular meetings should be held between testing teams, project managers, development teams, Business Analysts to check the progress of things which will give a fair idea of the movement of the project and ensure the completeness of the test plan created in the planning phase, which will further help in enhancing the right testing strategy created earlier. We will start creating test case formats and test cases itself. In this stage we need to develop Functional validation matrix based on Business Requirements to ensure that all system requirements are covered by one or more test cases, identify which test cases to automate, begin review of documentation, i.e. Functional Design, Business Requirements, Product Specifications, Product Externals etc. We also have to define areas for Stress and Performance testing.

Test Design

Test plans and cases, which were developed in the analysis phase, are revised. Functional validation matrix is also revised and finalized. In this stage risk assessment criteria is developed. If you have thought of automation then you have to select which test cases to automate and begin writing scripts for them. Test data is prepared. Standards for unit testing and pass / fail criteria are defined here. Schedule for testing is revised (if necessary) & finalized and test environment is prepared.

Construction and verification

In this phase we have to complete the entire test plans, test cases, complete the scripting of the automated test cases, Stress and Performance testing plans needs to be completed. We have to support the development team in their unit-testing phase. And obviously bug reporting would be done as when the bugs are found. Integration tests are performed and errors (if any) are reported.

Testing Cycles

In this phase we have to complete testing cycles until test cases are executed without errors or a predefined condition is reached. Run test cases --> Report Bugs --> revise test cases (if needed) --> add new test cases (if needed) --> bug fixing --> retesting (test cycle 2, test cycle 3….).

Final Testing and Implementation

In this we have to execute remaining stress and performance test cases, documentation for testing is completed / updated, provide and complete different matrices for testing. Acceptance, load and recovery testing will also be conducted and the application needs to be verified under production conditions.

Post Implementation

In this phase, the testing process is evaluated and lessons learnt from that testing process are documented. Line of attack to prevent similar problems in future projects is identified. Create plans to improve the processes. The recording of new errors and enhancements is an ongoing process. Cleaning up of test environment is done and test machines are restored to base lines in this stage.

Software Testing Life Cycle
PhaseActivitiesOutcome
PlanningCreate high level test planTest plan, Refined Specification
Analysis
Create detailed test plan, Functional Validation Matrix, test casesRevised Test Plan, Functional validation matrix, test cases
Design
Test cases are revised; select which test cases to automate Revised test cases, test data sets, sets, risk assessment sheet
ConstructionScripting of test cases to automate,Test procedures/Scripts, Drivers, test results, Bug Reports.
Testing cyclesComplete testing cyclesTest results, Bug Reports
Final testingExecute remaining stress and performance tests, complete documentation Test results and different metrics on test efforts
Post implementationEvaluate testing processesPlan for improvement of testing process