Different Methodologies Of Incremental Testing

The different methods for Incremental testing are

• Top-Down Method

• Bottom-up Method

• Sandwich Testing Method

Below is the detailed description of above method with the help of example

1. Top-Down Method

     As the name it is easy to identify that approach followed in this technique is from the top and moving to the bottom.Modules framing the top layer of application are tested first.

Here Stubs are used and are known as “called programs”. Stubs help simulate the interface between lower level modules which are not available or developed.

• Module: Website Login or Module L

• Module: Order or Module O

  • Module Order Summary or Stub OS (Not yet developed)

• Module: Payment or Module P

  • Module Cash Payment or Module CP

  • Module Debit/Credit Payment or Stub DP (Not yet developed)

  • Module Wallet Payment or Stub WP (Not yet developed)

• Module: Reporting or Stub R (Not yet developed)

Test cases for the above example will be

1. Module L and Module O will be integrated and tested

2. Module L, Module O and Module P will be integrated and tested.

3. Module L, Module O, Module P and Stub R will be integrated and tested.

And so on. In this type of technique firstly all the first layer is been included also called as ”breadth-first” after this we will start with the “depth-first”

Test cases for Depth-First will be

1. Module L and Module O will be integrated and tested first

2. Module L, Module 0 and Stub OS will be integrated and tested

3. Module L, Module O, Stub OS and Module P will be integrated and tested

4. Module L, Module O, Stub OS, Module P, Module CP will be integrated and tested

And further cases will be easily deprived

2. Bottom-Up Method

In this approach the layer which covers the bottom is tested first and then moved upwards.

In this approach Drivers are used and are known as “calling programs”. Drivers help simulate the interface between top level modules which are not developed or available.

The test cases for above example is as defined:

1. Unit Testing of Module Practical and Module theory

2. Integration of Modules Marks,Practical and theory followed by testing

3. Integration of Modules Percentage, Marks, Practical and theory followed by testing

4. Unit testing og module Sports Grades

5. Integration of all bottoms modules along with testing

3. Sandwich Testing Method

    This technique includes the part of both Top-Down method and Bottom-Up method and both stubs and drivers are used in this approach for incomplete or not developed modules.

Testing Approach

• The both types of testing are done from the middle layer so first the middle layer is identified which is also known as target layer.

• Target layer should contain minimal use of stubs and drivers. Target layer is identified according to the Heuristic approach.

• Top-Down testing starts from the middle and moves downward as explained above. Thus, the above layer to middle layer is known as Bottom layer

• Bottom-up testing starts from the middle and moves upwards as explained above. Thus, the above layer to middle layer is known as top layer

• With the use of stubs and drivers functions and user interface of lower level modules are tested

• At final stage the middle layer is only left out for execution and final testing.

Test cases for the above example will be as follows

1. First Test Modules A,X,Y and Z individually. Here Module A will be included in Top layer test and Module X,Y and Z will come under Bottom layer test.

2. Test Modules A,G,H and I

3. Test Module G,X and Y

4. Test Modules Z

5. Then all together test Modules A,G,H,I,X,Y and Z