Below are some of the important types of testing.

Functional Testing:

Functionality testing is performed to verify whether the product/application meets the intended specifications and the functional requirements mentioned in the documentation. Functional tests are written from a user's perspective. These tests confirm that the system does what the users are expecting it to do. Both positive and negative test cases are performed to verify the product/application responds correctly. Functional Testing is critically important for the products success since it is the customer's first opportunity to be disappointed.

 

Structural Testing:

In Structural testing, a white box testing approach is taken with focus on the internal mechanism of a system or component • Types of structural testing: – Branch testing – Path testing – Statement testing"

 

System Testing:

System testing of software or hardware is testing conducted on a complete, integrated system to evaluate the system's compliance with its specified requirements. System testing falls within the scope of black box testing, and as such, should require no knowledge of the inner design of the code or logic. System testing is performed on the entire system with reference of a Functional Requirement Specification(s) (FRS) and/or a System Requirement Specification (SRS).

 

Integration Testing:

Integration testing is the activity of software testing in which individual software modules are combined and tested as a group. Testing in which software components or hardware components or both are combined and tested to evaluate the interaction between them.

 

Unit Testing:

Testing of individual software components or groups of related components Testing conducted to evaluate whether systems or components pass data and control correctly to one another

Unit Test / Work Unit: Work Unit Testing:

• Code(Program)
• Module
• Function
• Sub-Program
• SP (Stored Procedure) Unit testing is done to ensure work units which make up the entire work product are working properly. It is easier to pinpoint and correct faults at a unit level. Unit Test Cases are part of the Unit Test Plan. Other levels of testing is to ensure the working of integrated work product.
  References: wikipedia.