1. White box Testing
White box testing strategy deals with the
internal logic and structure of the code. White box testing is also called as
glass, structural, open box or clear box testing. In order to implement white
box testing, the tester has to deal with the code and hence is needed to
possess knowledge of coding and logic i.e. internal working of the code.
a) Basis Path Testing
Each independent
path in the code is taken for testing.
b) Flow Graph Notation
The flow graph
depicts logical control flow using a diagrammatic notation. Each structured
construct has a corresponding flow graph symbol.
c) Cyclomatic Complexity
Cyclomatic
complexity is software metric that provides a quantitative measure of the
logical complexity of a program. In basis path testing method, the value
computed for Cyclomatic complexity defines the number for independent paths in
the basis set of a program and provides us with an upper bound for the number
of tests that must be conducted to ensure that all statements have been
executed at least once.
An independent path is any path through the
program that introduces at least one new set of processing statements or a new
condition.
Computing Cyclomatic Complexity
Cyclomatic
complexity has a foundation in graph theory and provides us with extremely
useful software metric. Complexity is computed in one of the three ways:
1. The number of
regions of the flow graph corresponds to the Cyclomatic complexity.
2. Cyclomatic
complexity, V (G), for a flow graph, G is defined as
V (G) = E-N+2
Where E, is the
number of flow graph edges, N is the number of flow graph nodes.
3. Cyclomatic
complexity, V (G) for a flow graph, G is also defined as:
V (G) = P+1
Where P is the
number of predicate nodes contained in the flow graph G.
d) Graph Matrices
The procedure for
deriving the flow graph and even determining a set of basis paths is amenable
to mechanization. To develop a software tool that assists in basis path
testing, a data structure, called a graph
matrix can be quite useful.
A Graph Matrix is a square matrix whose
size is equal to the number of nodes on the flow graph. Each row and column
corresponds to an identified node, and matrix entries correspond to connections
between nodes.
e) Control Structure Testing
Described below are
some of the variations of Control Structure Testing.
Condition Testing
Condition testing
is a test case design method that exercises the logical conditions contained in
a program module.
Data Flow Testing
The data flow
testing method selects test paths of a program according to the locations of
definitions and uses of variables in the program.
f) Loop Testing
Loop Testing is a
white box testing technique that focuses exclusively on the validity of loop
constructs. Four classes of loops can be defined: Simple loops, Concatenated
loops, nested loops, and unstructured loops.
Simple Loops
The following sets
of tests can be applied to simple loops, where ‘n’ is the maximum number of
allowable passes through the loop.
1. Skip the loop
entirely.
2. Only one passes
through the loop.
3. Two passes
through the loop.
4. ‘m’ passes
through the loop where m<n.
5. n-1, n, n+1 passes
through the loop.
Nested Loops
If we extend the
test approach for simple loops to nested loops, the number of possible tests
would grow geometrically as the level of nesting increases.
1. Start at the
innermost loop. Set all other loops to minimum values.
2. Conduct simple
loop tests for the innermost loop while holding the outer loops at their
minimum iteration parameter values. Add other tests for out-of-range or exclude
values.
3. Work outward,
conducting tests for the next loop, but keeping all other outer loops at
minimum values and other nested loops to “typical” values.
4. Continue until
all loops have been tested.
Concatenated Loops
Concatenated loops
can be tested using the approach defined for simple loops, if each of the loops
is independent of the other. However, if two loops are concatenated and the
loop counter for loop 1 is used as the initial value for loop 2, then the loops
are not independent.
Unstructured Loops
Whenever possible,
this class of loops should be redesigned to reflect the use of the structured
programming constructs.
2. Black box Testing
Black Box Testing is not a type of testing;
it instead is a testing strategy. It does not need any knowledge of internal
design or code etc. The types of testing under this strategy are totally
focused on the testing for requirements and functionality of the work software
application. It is also called as Opaque Testing, Functional/Behavioral Testing
and Closed Box Testing.
Techniques of Black box Testing:
a. Graph Based Testing Methods:
Each and every application is build up of some objects. All such objects are identified and graph is prepared. From this object graph each object relationship is identified and test cases written accordingly to discover the errors.
Each and every application is build up of some objects. All such objects are identified and graph is prepared. From this object graph each object relationship is identified and test cases written accordingly to discover the errors.
b. Error Guessing:
This is purely based on previous experience and judgment of tester. Error Guessing is the art of guessing where errors can be hidden. For this technique there are no specific tools, writing the test cases that cover all the application paths.
This is purely based on previous experience and judgment of tester. Error Guessing is the art of guessing where errors can be hidden. For this technique there are no specific tools, writing the test cases that cover all the application paths.
c. Boundary Value Analysis:
Boundary Value Analysis (BVA) is a test Functional Testing technique where the extreme boundary values are chosen. Boundary values include maximum, minimum, just inside/outside boundaries, typical values, and error values.
Boundary Value Analysis (BVA) is a test Functional Testing technique where the extreme boundary values are chosen. Boundary values include maximum, minimum, just inside/outside boundaries, typical values, and error values.
Look at output boundaries
for test cases too
Test min, min-1, max, max+1, typical values
Test min, min-1, max, max+1, typical values
BVA techniques:
1. Number of variables
For n variables: BVA yields 4n + 1 test cases.
2. Kinds of ranges
Generalizing ranges depends on the nature or type of variables
Advantages of Boundary Value Analysis
1. Robustness Testing - Boundary Value Analysis plus values that go beyond the limits
2. Min - 1, Min, Min +1, Nom, Max -1, Max, Max +1
3. Forces attention to exception handling
1. Number of variables
For n variables: BVA yields 4n + 1 test cases.
2. Kinds of ranges
Generalizing ranges depends on the nature or type of variables
Advantages of Boundary Value Analysis
1. Robustness Testing - Boundary Value Analysis plus values that go beyond the limits
2. Min - 1, Min, Min +1, Nom, Max -1, Max, Max +1
3. Forces attention to exception handling
Limitations of
Boundary Value Analysis:
Boundary value testing is efficient only for variables of fixed values i.e boundary.
Boundary value testing is efficient only for variables of fixed values i.e boundary.
d. Equivalence Partitioning:
Equivalence partitioning is a black box testing method that divides the input domain of a program into classes of data from which test cases can be derived.
Equivalence partitioning is a black box testing method that divides the input domain of a program into classes of data from which test cases can be derived.
How this
partitioning is performed while testing:
1. If an input condition specifies a range, one valid and one two invalid classes are defined.
2. If an input condition requires a specific value, one valid and two invalid equivalence classes are defined.
3. If an input condition specifies a member of a set, one valid and one invalid equivalence class is defined.
4. If an input condition is Boolean, one valid and one invalid class is defined.
1. If an input condition specifies a range, one valid and one two invalid classes are defined.
2. If an input condition requires a specific value, one valid and two invalid equivalence classes are defined.
3. If an input condition specifies a member of a set, one valid and one invalid equivalence class is defined.
4. If an input condition is Boolean, one valid and one invalid class is defined.
e. Comparison Testing:
Different independent versions of same software are used to compare to each other for testing in this method.
Different independent versions of same software are used to compare to each other for testing in this method.
Various testing
types that fall under the Black Box Testing strategy are: functional testing,
stress testing, recovery testing, volume testing, User Acceptance Testing (also
known as UAT), system testing, Sanity or Smoke testing, load testing, Usability
testing, Exploratory testing, ad-hoc testing, alpha testing, beta testing etc.
3. Structural System Testing Techniques
The
following are the structural system testing techniques.
|
Technique
|
Description
|
Example
|
|
Stress
|
Determine
system performance with expected volumes.
|
Sufficient
disk space allocated.
|
|
Execution
|
System
achieves desired level of proficiency.
|
Transaction
turnaround time adequate.
|
|
Recovery
|
System
can be returned to an operational status after a failure.
|
Evaluate
adequacy of backup data.
|
|
Operations
|
System
can be executed in a normal operational status.
|
Determine
systems can run using document.
|
|
Compliance
|
System
is developed in accordance with standards and procedures.
|
Standards
follow.
|
|
Security
|
System
is protected in accordance with importance to organization.
|
Access
denied.
|
4. Functional System Testing Techniques
The
following are the functional system testing techniques.
|
Technique
|
Description
|
Example
|
|
Requirements
|
System
performs as specified.
|
Prove
system requirements.
|
|
Regression
|
Verifies
that anything unchanged still performs correctly.
|
Unchanged
system segments function.
|
|
Error
Handling
|
Errors
can be prevented or detected and then corrected.
|
Error
introduced into the test.
|
|
Manual
Support
|
The
people-computer interaction works.
|
Manual
procedures developed.
|
|
Intersystem’s.
|
Data
is correctly passed from system to system.
|
Intersystem
parameters changed.
|
|
Control
|
Controls
reduce system risk to an acceptable level.
|
File
reconciliation procedures work.
|
|
Parallel
|
Old
systems and new system are run and the results compared to detect unplanned
differences.
|
Old
and new system can reconcile.
|
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