Design Patterns

Design Pattern: Standard design techniques and templates widely recognized as good practice.

Controller

Acts as a switchboard between Domain layer and View layer classes.

• Is a completely artificial class — an artifact.

Adapter

Place an adapter between your system and an external system.

Factory

Use factory class when creation logic is complex for a set of classes.

Singleton

Use when only one instance should exist at a time and is shared.

Testing

Testing: Process of determining whether a component/subsystem/system contains any defects.

Test Case: Formal description of a starting state, event(s) to which the software must respond, and the expected response/ending state.

Test Data: Set of starting states and events used to test a module(s)/system.

Common Types of Tests

1. Unit Testing
2. Integration
3. System and Stress
4. ???

Unit Testing

Unit Tests: Tests of an individual method, class, or component before it’s integrated with other software.

• Driver: Method/class developed that simulates the behavior of a method that sends a message to the method being called.
• Stub: Method/class that simulates the behavior of a method invoked that hasn’t yet been written.

Integration Testing

Integration Testing: Test of the behavior of a group of methods/classes/components.

• Interface Incompatibility:
  • e.g., a method passes parameter of wrong type to another method.
• Parameter Values: Method passes/returns unexpected value.
  • e.g., Negative number for a price.
• Run-time Exceptions:
  • e.g., “out of memory”, “file already in use”
• Unexpected State Interactions: States of two or more objects cause complex failures.
  • e.g., Cart and Customer object

System, Performance, and Stress Testing

System Test: Integration test of an entire system/independent subsystem.

• Can be performed at the end of each SDLC iteration and performed more frequently.
• Build and Smoke Test: System test that’s performed daily or several times a week.

Performance/Stress Test: Integration and usability test that determines whether a system/subsystem can meet time-based performance criteria.

• Response Time
• Throughput

User Acceptance Testing

User Acceptance Test: System test performed to determine whether the system fulfills user requirements.

Converting and Initializing Data

An operational system requires a fully-populated database to support ongoing processing.

Data needed at started can be obtained from:

• Files or databases of a system being replaced.
• Manual records
• Files or databases from other systems in the organization
• User feedback during normal system operation.

Note: Some engineers specialize in ETL (Extract Transfer Load). Transferring data can be very costly.

Training Users

Training is needed for end users and system operators.

• For End Users: Emphasize hands-on use.
• For System Operators: Can be much less formal.
  • System Documentation,
  • ????

Planning and Managing

Change and Version Control

Alpha Version:

Beta Version

Production Version / Release Version / Production Release

Maintenance Release: