System Integration Testing

Definition

System integration testing is the integration testing of two or more system components. Specifically, system integration testing is the testing of software components that have been distributed across multiple platforms (e.g., client, web server, application server, and database server) to produce failures caused by system integration defects (i.e., defects involving distribution and back-office integration).

Objectives

The typical objectives of system integration testing are to:

Cause failures involving the distribution of integrated system components.
Cause failures involving integration of the system with other applications (e.g., legacy back-office systems).
Report these failures to the development team so that they can be fixed.
Help the development team to ensure that the software has been successfully distributed to improve the effectiveness of system and launch testing.
Minimize the number of low-level defects that will prevent effective system and launch testing.

Preconditions

System integration testing can typically begin when the following preconditions hold:

The integration team is adequately staffed and trained in system integration testing.
The integration environment is ready.
At least two software components have:
- Passed the relevant software integration testing.
- Been ported to the integration environment.
- Been integrated.

Completion Criteria

System integration testing is typically complete when the following postconditions hold:

All system components have been integrated (e.g., software components have been distributed to their hardware components).
A system integration test suite of test cases exists for each interface between software components distributed to different hardware components.
All system integration test suites successfully execute (i.e., the tests completely execute and the actual test results match the expected test results).
The system passes the subset of the blackbox functional system tests provided by the independent test team, whereby these tests should exercise major system interfaces, especially between distributed software components and with external server systems.

Tasks

System integration testing typically involves the integration team performing the following testing tasks:

Environments

System integration testing is typically rformed on the following environments using the following tools:

Integration Environment
- Test Harness
- Record and playback tool

Phases

System integration testing typically consists of the following tasks being performed during the following phases:

TASK \ PHASE	Business Strategy	Business Optimization	Initiation	Construction	Delivery	Usage	Retirement
Test Planning	Not Applicable	Not Applicable	Started	Completed	Iterated	Iterated	Not Applicable
Test Reuse	Not Applicable	Not Applicable	Started	Completed	Iterated	Iterated	Not Applicable
Test Design	Not Applicable	Not Applicable	Started	Completed	Iterated	Iterated	Not Applicable
Test Implementation	Not Applicable	Not Applicable	Started	Completed	Iterated	Iterated	Not Applicable
Test Execution	Not Applicable	Not Applicable	Started	Completed	Iterated	Iterated	Not Applicable
Test Reporting	Not Applicable	Not Applicable	Started	Completed	Iterated	Iterated	Not Applicable

Guidelines

The iterative and incremental development cycle implies that system integration testing is regularly performed in an iterative and incremental manner.
System integration testing must be automated if adequate regression testing is to occur.
System integration testing can elicit failures produced by defects that are difficult to detect during system or launch testing once the system has been completely integrated.