System Testing: Why? What? & How?

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‘Unit testing’ focuses on testing each unit of the code.

‘Integration testing’ focuses on testing the integration of “units of code” or components.

Each level of testing builds on the previous level.

‘System Testing’ is the next level of testing. It focuses on testing the system as a whole.

This article attempts to take a close look at the System Testing Process and analyze:

Why System Testing is done? What are the necessary steps to perform System Testing? How to make it successful?
How does System Testing fit into the Software Development Life Cycle?
In a typical Enterprise, ‘unit testing’ is done by the programmers. This ensures that the individual components are working OK. The ‘Integration testing’ focuses on successful integration of all the individual pieces of software (components or units of code).
Once the components are integrated, the system as a whole needs to be rigorously tested to ensure that it meets the Quality Standards.
Thus the System testing builds on the previous levels of testing namely unit testing and Integration Testing.
Usually a dedicated testing team is responsible for doing ‘System Testing’. Why System Testing is important?
System Testing is a crucial step in Quality Management Process.
........- In the Software Development Life cycle System Testing is the first level where
...........the System is tested as a whole
........- The System is tested to verify if it meets the functional and technical
...........requirements
........- The application/System is tested in an environment that closely resembles the
...........production environment where the application will be finally deployed ........- The System Testing enables us to test, verify and validate both the Business
...........requirements as well as the Application Architecture
Prerequisites for System Testing:

The prerequisites for System Testing are:
........- All the components should have been successfully Unit Tested
........- All the components should have been successfully integrated and Integration
..........Testing should be completed
........- An Environment closely resembling the production environment should be ...........created.

When necessary, several iterations of System Testing are done in multiple environments.
Steps needed to do System Testing:

The following steps are important to perform System Testing:
........Step 1: Create a System Test Plan
........Step 2: Create Test Cases
........Step 3: Carefully Build Data used as Input for System Testing
........Step 3: If applicable create scripts to
..................- Build environment and
..................- to automate Execution of test cases
........Step 4: Execute the test cases
........Step 5: Fix the bugs if any and re test the code
........Step 6: Repeat the test cycle as necessary
What is a ‘System Test Plan’?

As you may have read in the other articles in the testing series, this document typically describes the following:
.........- The Testing Goals
.........- The key areas to be focused on while testing
.........- The Testing Deliverables
.........- How the tests will be carried out
.........- The list of things to be Tested
.........- Roles and Responsibilities
.........- Prerequisites to begin Testing
.........- Test Environment
.........- Assumptions
.........- What to do after a test is successfully carried out .........- What to do if test fails
.........- Glossary

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