Smoke tests refer orignally to hardware testing, wherein a device would be plugged in and if it started to smoke then it was unplugged as no further testing was required. It doesn't work, there is no point in testing it.

Sanity tests are, traditionally (in other realms of testing) tests that establish whether or not a result could be true, rather than if it is true, that is to say if the output is "sane". If you put "9" into the function "squareroot()" and get "badger" you have failed a sanity test. If you get, say, a positive number less than 9 then you have passed it, even if the number is not "3". This is why they refer to tests that ensure that the system is working enough to be tested - it is giving a sane response to basic tests, therefore it is not a waste of time to run full functional tests.

It is difficult to perform GUI(Graphical User Interface) regression testing when GUI structure is modified. The test cases written on old GUI either becomes obsolete or need to reuse. Reusing the regression testing test cases means GUI test cases are modified according to new GUI. But this task becomes cumbersome if you have large set of GUI test cases.

Automated Regression testing is the testing area where we can automate most of the testing efforts. We run all the previously executed test cases this means we have test case set available and running these test cases manually is time consuming. We know the expected results so automating these test cases is time saving and efficient regression testing method. Extent of automation depends on the number of test cases that are going to remain applicable over the time. If test cases are varying time to time as application scope goes on increasing then automation of regression procedure will be the waste of time.

Most of the regression testing tools are record and playback type. Means you will record the test cases by navigating through the AUT and verify whether expected results are coming or not.

Example regression testing tools are:

    Winrunner

    QTP

    AdventNet QEngine

    Regression Tester

    vTest

    Watir

    Selenium

    actiWate

    Rational Functional Tester

    SilkTest

Most of the tools are both Functional as well as regression testing tools.

Rerunning the previously conducted tests.

Comparing current results with previously executed test results.

This depends on the scope of new added feature. If the scope of the fix or feature is large then the application area getting affected is quite large and testing should be thoroughly including all the application test cases. But this can be effectively decided when tester gets input from developer about the scope, nature and amount of change.

Regression testing is initiated when programmer fix any bug or add new code for new functionality to the system. It is a quality measure to check that new code complies with old code and unmodified code is not getting affected.

Most of the time testing team has task to check the last minute changes in the system. In such situation testing only affected application area in necessary to complete the testing process in time with covering all major system aspects.

Regression means retesting the unchanged parts of the application. Test cases are re-executed in order to check whether previous functionality of application is working fine and new changes have not introduced any new bugs.

This is the method of verification. Verifying that the bugs are fixed and the newly added feature have not created in problem in previous working version of software.

(a) Spiral

(b) Water fall

(c) Agile software development

(d) Synchronize and stabilize

(e) Rapid prototyping

(f) Incremental etc.

(a) Requirement analysis

(b) Test analysis

(c) Test case development

(d) Environment set up

(e) Test execution

(f) Test cycle closure

Each of the above mentioned processes under software testing life cycle is provided with an entry criteria as well as exit criteria.