Written by Membar
Software Testing Techniques
Introduction
Exception handling is a programming language construct or computer
hardware mechanism designed to handle the occurrence of some
condition that changes the normal flow of execution. For signaling
conditions that are part of the normal flow of execution see the concepts
of signal and event handler.
Exception or error handling refers to the anticipation, detection, and
resolution of programming, application, and communications errors.
Specialized programs, called error handlers, are available for some
applications. The best programs of this type forestall errors if possible,
recover from them when they occur without terminating the application,
or (if all else fails) gracefully terminate an affected application and save
the error information to a log file.
In programming, a development error is one that can be prevented.
Such an error can occur in syntax or logic. Syntax errors, which are
typographical mistakes or improper use of special characters, are
handled by rigorous proofreading. Logic errors, also called bugs,
occur when executed code does not produce the expected or desired
result. Logic errors are best handled by meticulous program debugging.
This can be an ongoing process that involves, in addition to the traditional
debugging routine, beta testing prior to official release and customer feedback
after official release.
A run-time error takes place during the execution of a program, and usually
happens because of adverse system parameters or invalid input data. An
example is the lack of sufficient memory to run an application or a memory
conflict with another program. On the Internet, run-time errors can result from
electrical noise, various forms of malware or an exceptionally heavy demand on
a server. Run-time errors can be resolved, or their impact minimized, by the use
of error handler programs, by vigilance on the part of network and server
administrators, and by reasonable security countermeasures on the part of
Internet users. In runtime engine environments such as Java or .NET there exist
tools that attach to the runtime engine and every time that an exception of interest
occurs they record debugging information that existed in memory at the time the
exception was thrown (call stack and heap values). These tools are called
Automated Exception Handling or Error Interception tools and they provide
'root-cause' information for exceptions.
Usage
* It determines the ability of applications system to process the incorrect
transactions properly
* Errors encompass all unexpected conditions.
* In some system approx. 50% of programming effort will be devoted to
handling error condition.
Objective
* Determine Application system recognizes all expected error conditions.
* Determine Accountability of processing errors has been assigned and
procedures provide a high probability that errors will be properly
corrected.
* Determine During correction process reasonable control is maintained
over errors.
How to Use:
* A group of knowledgeable people is required to anticipate what can go
wrong in the application system.
* It is needed that all the application knowledgeable people assemble to
integrate their knowledge of user area, auditing and error tracking.
* Then logical test error conditions should be created based on this
assimilated information.
When to Use:
* Throughout SDLC.
* Impact from errors should be identified and should be corrected to
reduce the errors to acceptable level.
* Used to assist in error management process of system development
and maintenance.
Example:
* Create a set of erroneous transactions and enter them into the
application system then find out whether the system is able to
identify the problems.
* Using iterative testing enters transactions and trap errors.
Correct them. Then enter transactions with errors, which were
not present in the system earlier.
