Error handling in manual testing

See my prior article Saner Rails Logging for the answers to 2 and 3. By applying this technique to each of the components of completing a purchase, one can flush out and handle nearly all of the different possible errors that could affect a purchase. Give this technique a try in some critical section of the code. You'll be surprised how well it works. Before giving you the fix to the above code, let's see if we can write unit and feature tests on our error handling.

It turns out that with stubbing in rspec , it's easy to test error handling! RSpec provides a nice mocking library. The test code would look something like this.

Pay attention to the call to stub. It's possibly more important and sometimes easier to do the verification at the integration level in RSpec feature specs using Capybara with PhantomJs and Poltergeist.

The secret sauce is the same use of the same stubbing technique as above to replace some key methods such that they throw an exception. This sort of technique works amazingly well to ensure that application will do the right then when an unexpected failure occurs, from the logging and emailing of the error message to the browser display to then end user. Make sure you've got tests on the "happy" case where the story goes as planned. Then introduce test cases where have bits of code like this that will raise an error at an opportune time.

Take advantage of language-specific semantics and present when something exceptional has happened. Exceptions are thrown and caught therefore the code can recover and handle the situations and not enter a mistake state. This also lets the application can recover or continue. Where unhandled exceptions can also be logged so they are looked at by developer to fix the underlying error.

Error handling testing is a type of software testing that is done to check whether the system is capable of or able to handle errors that may happen in future. This type of testing is done with the help of both developers and testers. Error handling testing not only focuses on the determination of error but also focuses on the exception handling. Your email address will not be published.

Save my name, email, and website in this browser for the next time I comment. Data Flow Testing. Content Testing. Website or domain name. Related Posts:. However, this is sometimes complicated by the semi predicate problem, in which users of the routine need to write extra code to distinguish normal return values from erroneous ones. 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.

Contemporary applications face many design challenges when considering exception handling strategies. Particularly in modern enterprise level applications, exceptions must often cross process boundaries and machine boundaries. Part of designing a solid exception handling strategy is recognizing when a process has failed to the point where it cannot be economically handled by the software portion of the process.

A piece of code is said to be exception-safe, if run-time failures within the code will not produce ill effects, such as memory leaks, garbled stored data, or invalid output. Exception-safe code must satisfy invariants placed on the code even if exceptions occur.

There are several levels of exception safety:. When an item x is added to a vector v, the vector must actually add x to the internal list of objects and also update a count field that says how many objects are in v. This memory allocation may fail and throw an exception. Because of this, a vector that provides failure transparency would be very difficult or impossible to write.

However, the vector may be able to offer the strong exception guarantee fairly easily; in this case, either the insertion of x into v will succeed, or v will remain unchanged. If the vector provides only the basic exception safety guarantee, if the insertion fails, v may or may not contain x, but at least it will be in a consistent state. Usually at least basic exception safety is required.

Failure transparency is difficult to implement, and is usually not possible in libraries where complete knowledge of the application is not available. The point of exception handling routines is to ensure that the code can handle error conditions. In order to establish that exception handling routines are sufficiently robust, it is necessary to present the code with a wide spectrum of invalid or unexpected inputs, such as can be created via software fault injection and mutation testing which is also sometimes referred to as fuzz testing.

One of the most difficult types of software for which to write exception handling routines is protocol software, since a robust protocol implementation must be prepared to receive input that does not comply with the relevant specification s. In order to ensure that meaningful regression analysis can be conducted throughout a software development lifecycle process, any exception handling verification should be highly automated, and the test cases must be generated in a scientific, repeatable fashion.

Several commercially available systems exist that perform such testing. NET languages have built-in support for exceptions and exception handling. In those languages, the event of an exception more precisely, an exception handled by the language searches back through the stack of function calls until an exception handler is found, with some languages calling for unwinding the stack as the search progresses. That is, if function f contains a handler H for exception E, calls function g, which in turn calls function h, and an exception E occurs in h, then functions h and g may be terminated, and H in f will handle E.

An exception-handling language for which this is not true is Common Lisp with its Condition System. Common Lisp calls the exception handler and does not unwind the stack.

This allows to continue the computation at exactly the same place where the error occurred for example when a previously missing file is now available. Excluding minor syntactic differences, there are only a couple of exception handling styles in use.

In the most popular style, an exception is initiated by a special statement throw, or raise with an exception object e. Several handler clauses can follow, and each can specify which exception types it handles and what name it uses for the exception object. More common is a related clause finally, or ensure that is executed whether an exception occurred or not, typically to release resources acquired within the body of the exception-handling block.

In its whole, exception handling code might look like this in Java-like pseudocode; note that an exception type called EmptyLineException would need to be declared somewhere :. As a minor variation, some languages use a single handler clause, which deals with the class of the exception internally. The implementation of exception handling typically involves a fair amount of support from both a code generator and the runtime system accompanying a compiler.

Two schemes are most common. The first, dynamic registration, generates code that continually updates structures about the program state in terms of exception handling.

Typically, this adds a new element to the stack frame layout that knows what handlers are available for the function or method associated with that frame; if an exception is thrown, a pointer in the layout directs the runtime to the appropriate handler code.