Black box testing Methods

Black box testing Methods

1.Graph-based Testing Methods

Black-box methods based on the nature of the relationships (links)
among the program objects (nodes), test cases are designed to
traverse the entire graph

Transaction flow testing (nodes represent steps in some transaction
and links represent logical connections between steps that need to be
validated)

Finite state modeling (nodes represent user observable states of the
software and links represent transitions between states)

Data flow modeling (nodes are data objects and links are
transformations from one data object to another)

Timing modeling (nodes are program objects and links are sequential
connections between these objects, link weights are required
execution times)

2.Equivalence Partitioning

Black-box technique that divides the input domain into classes of
data from which test cases can be derived

An ideal test case uncovers a class of errors that might require many
arbitrary test cases to be executed before a general error is
observed

Equivalence class guidelines:

If input condition specifies a range, one valid and two invalid
equivalence classes are defined

If an input condition requires a specific value, one valid and
two invalid equivalence classes are defined

If an input condition specifies a member of a set, one valid
and one invalid equivalence class is defined

If an input condition is Boolean, one valid and one invalid
equivalence class is defined

3.Boundary Value Analysis

Black-box technique that focuses on the boundaries of the input
domain rather than its center

BVA guidelines:

If input condition specifies a range bounded by values a and b,
test cases should include a and b, values just above and just
below a and b

If an input condition specifies and number of values, test
cases should be exercise the minimum and maximum numbers, as
well as values just above and just below the minimum and
maximum values

Apply guidelines 1 and 2 to output conditions, test cases
should be designed to produce the minimum and maxim output
reports

If internal program data structures have boundaries (e.g. size
limitations), be certain to test the boundaries

4.Comparison Testing

Black-box testing for safety critical systems in which independently
developed implementations of redundant systems are tested for
conformance to specifications

Often equivalence class partitioning is used to develop a common set
of test cases for each implementation

5.Orthogonal Array Testing

Black-box technique that enables the design of a reasonably small set
of test cases that provide maximum test coverage

Focus is on categories of faulty logic likely to be present in the
software component (without examining the code)

Priorities for assessing tests using an orthogonal array

Detect and isolate all single mode faults

Detect all double mode faults

Multimode faults

6.Specialized Testing

Graphical user interfaces

Client/server architectures

Documentation and help facilities

Real-time systems

Task testing (test each time dependent task independently)

Behavioral testing (simulate system response to external
events)

Intertask testing (check communications errors among tasks)

System testing (check interaction of integrated system software
and hardware)

7.Advantages of Black Box Testing

More effective on larger units of code than glass box testing

Tester needs no knowledge of implementation, including specific
programming languages

Tester and programmer are independent of each other

Tests are done from a user's point of view

Will help to expose any ambiguities or inconsistencies in the
specifications

Test cases can be designed as soon as the specifications are complete

8.Disadvantages of Black Box Testing

Only a small number of possible inputs can actually be tested, to
test every possible input stream would take nearly forever

Without clear and concise specifications, test cases are hard to
design

There may be unnecessary repetition of test inputs if the tester is
not informed of test cases the programmer has already tried

May leave many program paths untested

Cannot be directed toward specific segments of code which may be very
complex (and therefore more error prone)

Most testing related research has been directed toward glass box
testing