Test2 - t timecriticalsystems undependable t t Abedinejad...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Abedinejad – Advanced Programming Software testing Issues in Software Testing Increasing demand for high software quality  time-critical systems  safety-critical systems Software systems have a reputation for being  undependable.   Build confidence that the system will work  without error after testing is the goal 
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Abedinejad – Advanced Programming Software testing Explosion of Ariane 5 A rocket capable of hurling a pair of three-ton  satellites into orbit with each launch  Loss destroyed 40 seconds after liftoff,  $500 million loss (June 4, 1996) Software Bug  mapping 64-bit float to 16-bit signed caused “horizontal velocity” to exceed  32767. software exception activated automatic  destruct
Background image of page 2
Abedinejad – Advanced Programming Software testing Failure of Therac 25 Therac-25 was a medical linear accelerator, a device used to treat cancer.   Radiation Treatment Machine made by  Atomic Energy of Canada, Ltd. Loss (1985-1987) Four patients killed Huge lawsuit Software Bug Delivered maximum power regardless of  operator’s setting
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Abedinejad – Advanced Programming Software testing Patriot Missile Failure on February 25, 1991 during gulf war Patriot Failed to track Scud Missile 28 soldiers killed, 100 injured Software Bug  1/10th (in binary) =  0.000110011001100110011001100110011001100 …… Truncation to 24 bits causes error of about  0.000000095 decimal. In 100 hours, this added up to 500 meters
Background image of page 4
Abedinejad – Advanced Programming Software testing What Makes Testing So Difficult? Inherent complexity of software Constructing an operational environment for  testing purpose Intractable and undecidable nature of testing Errors manifest themselves in rare states, yet  crucially important.    Murphy’s Law
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Abedinejad – Advanced Programming Software testing Testing Guidelines - 50% of program development effort goes into testing, primarily integration testing - Testing can show the presence of faults but not their absence - The act of designing tests is one of the most effective error prevention mechanisms known
Background image of page 6
Abedinejad – Advanced Programming Software testing Some Definitions Verification : has the program been implemented correctly? (test for presision) Validation : has the correct program been implemented (test for accuracy) Testing : the process of executing a program with the intent of detecting problems
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Abedinejad – Advanced Programming Software testing Some More Definitions Error : a mistake made in the process of constructing software (before the software is released to the end user) Fault/bug/defect : the manifestation of an error in the software (After the software has been released to the end user) Failure: a condition arising when executing software produces an incorrect result
Background image of page 8
Abedinejad – Advanced Programming Software testing
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 11/21/2010 for the course COMPUTER S 002 taught by Professor Ramtinkhosravi during the Spring '10 term at Amirkabir University of Technology.

Page1 / 39

Test2 - t timecriticalsystems undependable t t Abedinejad...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online