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Software testing strategies And its types
- 2. A Strategic Approach to Testing • To perform effective testing, a software team should conduct effective formal technical reviews • Testing begins at the component level and work outward toward the integration of the entire computer based system • Different testing techniques are appropriate at different points in time • Testing is conducted by the developer of the software and (for large projects) by an independent test group
- 3. Verification and Validation • Verification (Are the algorithms coded correctly?) – The set of activities that ensure that software correctly implements a specific function or algorithm • Validation (Does it meet user requirements?) – The set of activities that ensure that the software that has been built is traceable to customer requirements. • Verification: “Are we building the product right?” • Validation: “Are we building the right product?”
- 4. Software testing strategy • Unit testing – Concentrates on each component/function of the software as implemented in the source code • Integration testing – Focuses on the design and construction of the software architecture • Validation testing – Requirements are validated against the constructed software • System testing – The software and other system elements are tested as a whole
- 6. Test Strategies for Conventional Software Unit testing : • Focuses testing on the function or software module • Concentrates on the internal processing logic and data structures • Concentrates on modules and those with high cyclomatic complexity when testing resources are limited.
- 7. Unit testing
- 8. Unit testing considerations • Module interface – Ensure that information flows properly into and out of the module • Local data structures – Ensure that data stored temporarily maintains its integrity during all steps in an algorithm execution • Boundary conditions – Ensure that the module operates properly at boundary values established to limit or restrict processing • Independent paths (basis paths) – Paths are exercised to ensure that all statements in a module have been executed at least once • Error handling paths – Ensure that the algorithms respond correctly to specific error conditions
- 9. Unit test procedures • Driver – A simple main program that accepts test case data, passes such data to the component being tested, and prints the returned results • Stubs – Serve to replace modules that are subordinate to (called by) the component to be tested
- 11. Integration testing • Defined as a systematic technique for constructing the software architecture • Objective is to take unit tested modules and build a program structure based on the prescribed design • TwoApproaches – Non-incremental Integration Testing – Incremental Integration Testing
- 12. Non-incremental Integration Testing • Uses “Big Bang” approach • All components are combined in advance • The entire program is tested as a whole results • Correction is difficult because isolation of causes is complicated
- 13. Incremental Integration Testing • The program is constructed and tested in small increments • Errors are easier to isolate and correct • Interfaces are more likely to be tested completely • A systematic test approach is applied • Different incremental integration strategies – Top-down integration – Bottom-up integration – Regression testing – Smoke testing
- 14. Top-down Integration • Modules are integrated by moving downward through the control hierarchy, beginning with the main module • Subordinate modules are incorporated in two ways : – depth-first : All modules on a major control path are integrated – breadth-first : All modules directly subordinate at each level are integrated • Advantages – This approach verifies major control or decision points early in the test process • Disadvantages – Stubs need to be created to substitute for modules that have not been built or tested yet; this code is later discarded
- 15. Bottom-up Integration • Integration and testing starts with the most atomic modules in the control hierarchy • Advantages – This approach verifies low-level data processing early in the testing process – Need for stubs is eliminated • Disadvantages – Driver modules need to be built to test the lower- level modules; this code is later discarded or expanded into a full-featured version
- 16. Regression Testing • Each new addition or modification of data may cause problems with functions that previously worked flawlessly • Regression testing re-executes a small subset of tests that have already been conducted – Ensures that changes have not propagated unintended side effects – Helps to ensure that changes do not introduce unintended behavior or additional errors • Regression test suite contains three different classes of test cases – A representative sample of tests that will exercise all software functions – Additional tests that focus on software functions that are likely to be affected by the change – Tests that focus on the actual software components that have been changed
- 17. Smoke testing • Designedfor time-critical projects– Allows the software team to assess its project on a frequent basis • Includes the following activities – The software components that have been translated into code and linked into a build – A series of breadth tests is designed to expose errors that will keep the build from properly performing its function – The build is integrated with other builds and the entire product is smoke tested daily
- 18. • Integration risk is minimized – Daily testing uncovers incompatibilities and show- stoppers early in the testing process, thereby reducing schedule impact • The quality of the end-product is improved – Smoke testing is likely to uncover both functional errors and architectural and component-level design errors • Error diagnosis and correction are simplified – Smoke testing will probably uncover errors in the newest components that were integrated • Progress is easier to assess – As integration testing progresses, more software has been integrated and more has been demonstrated to work – Managers get a good indication that progress is Benefits of Smoke Testing
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