SE 754NT

1
SE 754-NT Object-Oriented Testing and
Reliability Robert Oshana Lecture
23 For more information, please
contact NTU Tape Orders NTU Media
Services [phone]
oshana_at_airmail.net
tapeorders_at_ntu.edu
2
Where we are

• Introduction
• The testing perspective
• Planning for testing
• Testing analysis and design models
• Class testing basics
• Testing interactions
• Testing class hierarchies
• Testing distributed objects
• Testing systems
• Components, frameworks, product lines

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Testing Distributed Objects (tests for the
generic distribution model)

• Chapter 8

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Language dependence issues

• Specific tests should be designed where two
  components written in different languages
  interface even through the infrastructure
• Inspectors should verify that correct mappings
  are used through guided inspection
• Return objects handled correctly

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Platform independence issues

• All of the models of distribution are independent
  of the platform on which they run
• Deployment environment still makes a difference
• Available memory
• Processor speed
• Deployment tests with product release

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Infrastructure tests

• Infrastructure delivered from a vendor is
  trusted code
• No detailed testing
• Default implementations of stubs and skeletons
  may be edited
• No longer trusted and must be tested
• Test all modified code

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Compatibility tests

• Performed with each new version of infrastructure
• Compatibility tests should be run to determine if
  application has to be modified
• Also done for new versions of frameworks and tools

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Testing the recovery of failures

• Big difference in distributed systems is partial
  failure due to one of the machines failing
• Build a test infrastructure using a main machine
  for locator and server
• Test driver for application to contact
  non-existent server
• Must be able to handle successfully

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Dynamic modification of infrastructure

• CORBA infrastructure can be modified during
  execution
• These modifications can change the configuration
  of the system
• Timing changes
• Execution path
• Must construct tests for these configurations

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Different sequences of events

• Asynchronous messages between processes cause
  events to occur in a variety of sequences
• Try to test as many possible combinations as
  possible
• Statistical sampling techniques can be used

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Requested object unavailable

• Many systems provide ability for users to enter
  names of providers and resources
• Test objective is to determine whether the
  exception is caught in an appropriate location in
  the requestor
• Will operation abort gracefully

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Test case summary

• Use the test suite giving the following coverages
• Every method of each standard I/F
• Every SYN-path
• Every logical control path

• Apply test suite repeatedly using following
  variations
• Load of applications using same systems
• Load of user input into overall system
• Connections between machines
• Configurations of the infrastructure

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The internet

• Very large and dynamic distributed system
• Web pages include data and behavior
• Testing a web page
• testing that the intended display is presented to
  the user
• Input accepted and forwarded correctly
• All actions perform as intended

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The internet

• Display failures
• Incorrect fonts displayed
• Mismatch of coordinates (figure not visible)
• Wrong language used
• Mismatch between platform configuration and
  browser attributes

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The internet

• Script testing
• Incorrect/insufficient permissions to execute
  code
• Inability to create a file when needed
• Computing the wrong answer
• Inability to locate resources
• Very difficult to tests for all combinations
  (focus on uses that make sense)

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Web servers

• Servers are generic vendor applications (trusted)
• Designed to be modular
• Testing these systems
• Do scripts do what is intended?
• Is the current data correct and in the form
  expected by the application?

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Web server architecture
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Life cycle testing of internet applications

• Testing across a set of user transactions
• Selected to utilize a complete set of backend
  applications
• Life cycle perspective
• Users system
• Web site
• Supplier applications

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Life cycle testing of internet applications

• 1. Presentation to the user
• 2. Acceptance of input (customer order)
• 3. Modification of input (order)
• Significant interaction testing in two dimensions
• Stress test the web site

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Summary

• One of the principle differences between
  distributed and nondistributed systems is the
  importance of timing
• Temporal logic can be used as a means of being
  expressive
• Instrumentation to allow the investigation of the
  effects of various sequences

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Testing systems

• Chapter 9

22
Where we are

• Introduction
• The testing perspective
• Planning for testing
• Testing analysis and design models
• Class testing basics
• Testing interactions
• Testing class hierarchies
• Testing distributed objects
• Testing systems
• Components, frameworks, product lines

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Introduction

• System testing can be classified as the testing
  of a completed application to determine that it
  provides all of the behaviors required for the
  application
• Change from searching for defects that cause
  program failures to search for variances between
  operation and system requirements

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Defining the system test plan

• A more formal and comprehensive document
• Features tested and not tested
• Some validation at each increment
• Test suspension criteria and resumption
  requirements
• System testers are not developers or debuggers

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Strategies for selecting test cases use profile

• Traditional approach is based on operational
  profiles
• A use profile is an accurate estimate of the
  operational profile
• Priority rather than the frequency
• Consider criticality as well as frequency

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SE 754-NT Object-Oriented Testing and
Reliability Robert Oshana End of
lecture For more information, please
contact NTU Tape Orders NTU Media
Services [phone]
oshana_at_airmail.net
tapeorders_at_ntu.edu