Software Testing: Identifying Faults, Errors, and Failures, Summaries of Software Engineering

Download Software Testing: Identifying Faults, Errors, and Failures and more Summaries Software Engineering in PDF only on Docsity!

Software Testing

Manar Elkady Some of the material are retrieved from a previous course offering by Dr.Soha Makady and Prof. Amr Kamel

Code Example 2: Fault, Error, Failure

public static void isLeap(int year) { if (year % 4 != 0) return false; if (year % 400 == 0) return true; if (year % 100 < 0) return false; return true; }

Leap Year

• Any year that is evenly divisible by 4 is a leap year.

• for example, 1988, 1992, and 1996 are leap years.

public static bool isLeap(int year)

if (year % 4 != 0) return false;

return true;

Leap Year

• A year that is evenly divisible by 100 (for example, 1900) is

a leap year only if it is also evenly divisible by 400.

public static bool isLeap(int year)

if (year % 4 != 0) return false;

return true;

Code Example 2: Fault, Error, Failure

public static bool isLeap(int year) { if (year % 4 != 0) return false; if (year % 400 == 0) return true; if (year % 100 < 0) return false; return true; } Execution states:

• Year = 2000, PC = isLeap()
• Year = 2000, PC = if (year % 4 != 0)
• Year = 2000, PC = if (year % 400 == 0)
• Year = 2000, PC = return true; Did we reach the fault? Did we infect?

Code Example 2: Fault, Error, Failure

public static void isLeap(int year) { if (year % 4 != 0) return false; if (year % 400 == 0) return true; if (year % 100 < 0) return false; return true; } Execution states:

• Year = 2001, PC = isLeap()
• Year = 2001, PC = if (year % 4 != 0)
• Year = 2001, PC = return false; Did we reach the fault? Did we infect?

Code Example 2: Fault, Error, Failure

public static void isLeap(int year) { if (year % 4 != 0) return false; if (year % 400 == 0) return true; if (year % 100 < 0) return false; return true; } Execution states:

• Year = 2100, PC = isLeap()
• Year = 2100, PC = if (year % 4 != 0)
• Year = 2100, PC = if (year % 400 == 0)
• Year = 2100, PC = if (year % 100 < 0)
• Year = 2100, PC = return true; Did we reach the fault? Did we infect? The year 2100 is not a leap year in the Gregorian calendar (because while it is divisible by 4, it is also divisible by 100 but not 400)

Introduction to Software Testing, Edition 2 (Ch 2) © Ammann & Offutt 11

Testing & Debugging

• Testing : Evaluating software by observing its execution
• Test Failure : Execution of a test that results in a software

failure

• Debugging : The process of finding a fault given a failure

Not all inputs will “trigger” a fault into

causing a failure

RIP-R Model

• Reachability

• Infection

• Propagation

• Revealability

Test Fault Incorrect Program State Test Oracles Final Program State Observed Final Program State Reaches Infects Propagates Reveals Incorrect Final State © Ammann & Offutt 13 Introduction to Software Testing, Edition 2 (Ch 2) Observed Final Program State

How do we deal with Faults, Errors, and Failures?

Software Testing – Basic Definitions (Cont’d)

• Test case: A test case is a test-related item which contains the following information: - A set of test inputs - Execution conditions - Expected outputs
• Test suite: A test suite is a group of related test cases.
• Test oracle: A program, a document, or a formula that produces or specifies the expected outcome of a test, can serve as an oracle. - Are oracles easy to construct? E.g., GUI-testing,

usability testing.