Incremental Testing in Software Testing

Incremental Testing :
Like development, testing is also a phase of SDLC (Software Development Life Cycle). Different tests are performed at different stages of the development cycle. Incremental testing is one of the testing approaches that is commonly used in the software field during the testing phase of integration testing which is performed after unit testing. Several stubs and drivers are used to test the modules one after one which helps in discovering errors and defects in the specific modules. 

Let's understand it more simply, after the completion of unit testing, integration testing is performed accordingly which is the simple process of detecting the interface and interaction between different modules. So, while the ongoing process of integration takes place there are a lot of methods and technology used one of which is incremental testing. It’s a kind of approach where developers sum up the modules one after one using stubs or drivers to unfold the defects.

Within incremental testing a range of possibilities exists and several Methodologies. 
Let's have a look at them:  

1. Top-down incremental integration -
   In this, the modules are tested top to bottom according to the architectural design meanwhile following control flow. Unavailable Components or systems are easily replaced by stubs.
2. Bottom-Up integration -
   This type of integration testing occurs from bottom to top. Control flow also takes place in an upward direction. Unavailable components or systems are easily substituted by drivers.
3. Functional incremental Integration -
   In this, both integration and testing take place and are completed based on functionalities or specified functional documents.

These several methodologies for incremental Testing which include some steps followed are discussed below 

• All the used modules are individually tested using the unit tests.
• Each module combines and gets tested by incrementing by one.
• The recent module is added to previously integrated modules and then goes through the test process.
• Then the last module gets incremented and all the modules are tested together for a successful integration.

Feature of continual Testing :

• Each module plays a specific role which is played in structuring the project.
• Every module has clearly defined dependencies that are used during Runtime.
• The biggest advantage of incremental testing is detecting the root cause of defects that are found in the early stage within smaller assemblies.

Advantages of Incremental Testing :

• Each module has its specific significance. Each one gets a role to play during the testing as they are incremented individually.
• Defects are detected in smaller modules rather than denoting errors and then editing and re-correcting large files.
• It's more flexible and cost-efficient as per requirements and scopes.
• The customer gets the chance to respond to each building.

Drawback faced :
Since Stubs and drivers are developed and also need constant updates before being used in the test, this process consumes a little bit of extra time.