Key Points

• Common patterns of component/object test automation
• How intelligent test artifacts as an architectural foundation can address common patterns of component/object testing, speeding test development and reducing test maintenance
• Implementing intelligent test artifacts in Java

Abstract

Component testing is the act of subdividing an object-oriented software system into units of particular granularity, applying stimuli to the component’s interface and validating the correct responses to those stimuli, in the form of either a state change or reaction in the component, or elsewhere in the system. 

In the last few years, design patterns have become a currency for communicating common problems and their solutions within a context. Testing is no exception. Several publications have endeavored to document common design solutions to component test automation problems in terms of design patterns.  

This article presents a set of design patterns commonly encountered when creating automated test frameworks and application domain specific test cases, and introduces the notion of test artifacts as an abstract test component implementation model. 

For most types of component testing, the component test developer must eventually find answers to one or more of the following questions, and possibly the questions that their answers pose: 

• How do I create a specifically configured instance of a component under test?
• How to I manage the application of a stimulus to the component under test?
• How do I organize stimuli into reusable groups?
• How to I validate the state of the component and system under test after one or more stimuli?
• How do I manage reference objects?
• How do I compare references objects to target objects, so that just the states that are important are compared?
• How do I intelligently traverse the state of my object under test
• How do I manage variations on test inputs in order to drive different paths with the same test stimuli?
• How do I verify that expected exceptions are raised?
• How do I map development activities to the tests that validate their correctness?

The presentation describes several patterns for automated component test framework and test case design, some familiar and some not, and introduces the notion of test artifacts as a component architecture for implementing tests. Examples use the Javaä programming language. These patterns include: 

• Test Component - Implement a reusable component model to represent aspects of automated testing.
• Test Sequence - Present a complete or commonly implemented subset of a test as a discrete, reusable unit.
• Configured Instance - Provide an instance of an object configured to a particular state
• Test Stimulus - Encapsulate a stimulus/response validation operation for a component under test for singly or multiply threaded systems.
• State Validation - Assert that a component is in the expected state. Define this assertion as a reusable component.
• Impression - Express a particular view of the state of a component in a compact, but human readable form
• Nested State - Provide a mechanism for specifying and traversing a chain of object references to extract a specific state
• Aggregate State - Represent the state of a component in terms of an aggregate set or subset of the states of its subcomponents.
• Object Variation - Organize configured object variations

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