1. Software System Integration
Chapter 8 Software testing

2. Chapter 8 Software testing
Overview
What is system integration?
Integration process description
Integration testing
System Integration Checklist
Chapter 8 Software testing

3. By the end of this session, you will..
Understand the importance and role of system integration
Understand the system integration process
Understand what is top-down and bottom-up integration
Understand what should be done before and during system integration
Chapter 8 Software testing

4. What is system integration?
System integration is the successful putting together of the various components, assemblies, and subsystems of a system and having them work together to perform what the system was intended to do.
Successful system integration results from the proper implementation of project activities
Deployment
Requirements
Design
Coding and unit Testing
Integration & test
Acceptance
Chapter 8 Software testing

5. Integration process planning
Chapter 8 Software testing

6. System integration process (1)
Integration is iterative and progressive, with each level of integration building from and on top of the previous level of integration
Integration and testing are part of the development process and are used to ensure all the various pieces work together in performing their higher-level functions.
Chapter 8 Software testing

7. System integration process (2)
Chapter 8 Software testing

8. Chapter 8 Software testing
Interfaces (1)
Complete Knowledge of all interfaces is essential to any integration effort.
This includes interfaces between :
components,
assemblies,
subsystems,
and also the system and other systems it needs to work with.
Chapter 8 Software testing

9. Chapter 8 Software testing
Interfaces (2)
Chapter 8 Software testing

10. Complete system integration(1)
Most systems consist of both hardware and software. These two are sometimes looked at as complete systems in and of themselves, but they cannot function independently of each other
There are two other system elements: people and support systems that are also part of the complete system.
For a system to be successfully implemented and used, all these elements must be in place and functioning correctly
Chapter 8 Software testing

11. Complete system integration(2)
Chapter 8 Software testing

12. Chapter 8 Software testing
Integration testing
Integration testing involves building a system from its components and testing it for problems that arise from component interactions.
Initial approach: “Big Bang”
Incremental integration
Top-down integration
Bottom-up integration
Sandwich integration
Chapter 8 Software testing

13. Chapter 8 Software testing
Top-down Integration Algorithm Develops the skeleton of the system and populate it with components.
Use Main control module as a test driver and substitute all modules that are directly subordinate to it by stubs.
Depending on the integration approach selected (depth first or breadth first), choose a stub and replace it by a real module.
Tests are conducted after replacement of a stub by a real module.
While there exist stubs in the system, go to step 2(loop)
Stop when the whole system structure is built and no stubs remain.
Chapter 8 Software testing

14. Top-down Integration What is a stub?
It is a test module that replaces a called module and that has exactly the same interface.
Stub A
Stub D
Stub B
Stub C
- Combine B and C
- Display a trace message
Return a value from a table (or external file)
- Display passed perameter
Chapter 8 Software testing

15. Chapter 8 Software testing
Bottom-up Integration Algorithm Integrates components at the lowest levels then adds functional components when going to the upper levels.
Construct drivers for low level modules.
Execute and test each driver separately.
Remove drivers and combine modules moving upward into clusters that perform a specific software sub- function. When the main module is reached go to 5)
Construct a driver per cluster. Go to 2)
Stop when the whole system structure is built and no drivers remain.
Chapter 8 Software testing

16. Bottom-up integration What is a driver?
A driver is a test module that replaces a real calling module and that has exactly the same interface.
Driver A
Driver D
Driver B
Driver C
- Send known parameter
Call real module
display parameter
- Invoke subordinate
Call real module
Display parameter
- Send known parameter
- Call real module
Chapter 8 Software testing

17. System integration checklist Before starting
Do your test plans include and support integration efforts?
Does your development plan allocate adequate time and resources for system integration efforts, including rework time?
Are the interfaces between components, assemblies, subsystems, and systems defined in adequate detail?
Will hardware be available for testing software during integration?
Is there a contingency plan if the schedule slips and if the integration schedule is compressed?
Are all elements of the system included in the integration plan?
Is all documentation current and available for reference?
Chapter 8 Software testing

18. System integration checklist During integration (1)
Is there an efficient rework cycle in place to fix problems found during integration testing?
Are “fixed” modules or components integrated and retested at all levels of integration up to the level where the problem was found?
Is the people element (operators, maintainers, logisticians, trainers, etc.) being prepared to work with the system when it is deployed?
Is the support systems element (logistics, maintenance, training, etc.) being prepared to support the new system when it is deployed?
Are you following an iterative, progressive integration process?
Are experienced integrators involved with the integration?
Chapter 8 Software testing

19. System integration checklist During integration (2)
Are area/subject matter experts involved with the integration?
Is adequate time being allowed for integration, testing, rework, reintegration, and retesting?
Are all necessary resources being made available for integration?
Is adequate testing being performed on integrated units (assemblies, subsystems, elements, system) to ensure that there are no surprises during acceptance testing?
Are you updating documentation during rework?
Are integration and system test errors being traced back to requirements and design? And if so, are the requirements and design being updated?
Chapter 8 Software testing

20. Chapter 8 Software testing
References
Guide to Software Engineering Body of Knowledge, especially Appendix D:
NASA Systems Engineering Handbook:
Software Engineering Institute:
System Engineering Fundamentals, 2001, Defense Acquisition University, download at:
Chapter 8 Software testing