Difference
b/w Black Box, White Box and Grey Box Testing
Black
Box Testing
The technique of testing without
having any knowledge of the interior workings of the application is Black Box
testing. Typically, when performing a black box test, a tester will interact
with the system's user interface by providing inputs and examining outputs
without knowing how and where the inputs are worked upon.
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Advantages
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Disadvantages
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- Well suited and efficient for
large code segments.
- Code Access not required.
- Clearly separates user's
perspective from the developer's perspective through visibly defined
roles.
- Large numbers of moderately
skilled testers can test the application with no knowledge of
implementation, programming language or operating systems.
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- Limited Coverage since only a
selected number of test scenarios are actually performed.
- Inefficient testing, due to
the fact that the tester only has limited knowledge about an
application.
- Blind Coverage, since the
tester cannot target specific code segments or error prone areas.
- The test cases are difficult
to design.
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White
Box Testing
White box testing is the detailed
investigation of internal logic and structure of the code. White box testing is
also called glass testing or open box testing. In order to perform white box
testing on an application, the tester needs to possess knowledge of the
internal working of the code.
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Advantages
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Disadvantages
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- As the tester has knowledge
of the source code, it becomes very easy to find out which type of data
can help in testing the application effectively.
- It helps in optimizing the
code.
- Extra lines of code can be
removed which can bring in hidden defects.
- Due to the tester's knowledge
about the code, maximum coverage is attained during test scenario
writing.
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- Due to the fact that a
skilled tester is needed to perform white box testing, the costs are
increased.
- Sometimes it is impossible to
look into every nook and corner to find out hidden errors that may
create problems as many paths will go untested.
- It is difficult to maintain
white box testing as the use of specialized tools like code analyzers
and debugging tools are required.
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Grey
Box Testing
Grey Box testing is a technique to
test the application with limited knowledge of the internal workings of an
application. In software testing, the term the more you know the better
carries a lot of weight when testing an application.
Mastering the domain of a system
always gives the tester an edge over someone with limited domain knowledge.
Unlike black box testing, where the tester only tests the application's user
interface, in grey box testing, the tester has access to design documents and
the database. Having this knowledge, the tester is able to better prepare test
data and test scenarios when making the test plan.
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Advantages
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Disadvantages
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- Offers combined benefits of
black box and white box testing wherever possible.
- Grey box testers don't rely
on the source code; instead they rely on interface definition and
functional specifications.
- Based on the limited
information available, a grey box tester can design excellent test
scenarios especially around communication protocols and data type
handling.
- The test is done from the
point of view of the user and not the designer.
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- Since the access to source
code is not available, the ability to go over the code and test coverage
is limited.
- The tests can be redundant if
the software designer has already run a test case.
- Testing every possible input
stream is unrealistic because it would take an unreasonable amount of
time; therefore, many program paths will go untested.
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