2. Abdisalam Issa-Salwe, Thames Valley University
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Topic list
Testing methods of testing
Developing a testing strategy
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Decision table
A decision table is a tabular
representation for conditional action.
It was developed as a design
technique for complicated decisions.
The first half of a decision table
specifies possible combinations of
conditions; the second half arranged
below the first, specifies the actions
taken for each combination.
The first half are guards for actions in
the second half.
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Decision table (cont...)
This technique works well for a few,
strongly interrelated conditions and
actions. It makes information easy to
determine but sequence information is
implicit.
Decision tables and decision trees help
us consider all the possible actions
that need be taken under a given set
of circumstances in a complete and
unambiguous fashion.
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Decision table (cont...)
To design a decision table:
Specify the name of the table as its
heading, and insert a reference to it
at the place in the process
description where the table applies
List all possible conditions in the
condition stub
List all possible actions in the action
stub
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Decision table (cont...)
Fill in the condition entries by marking
the presence (Y) or absence (N) of the
conditions. The number of rules, that
is, entries in the right-hand side of the
table equals the number of possible
combinations of conditions.
For every condition entry, mark with
an X an action entry opposite the
action(s) to be taken under these
circumstances.
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Decision table (cont...)
Characteristics of decision trees
They are easier to read than are
decision tables, but the greater
the number of conditions, the
more tedious they are to draw
up.
They are better for checking the
completeness of the policy
represented.
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Conditions
Is it 8 o’clock yet?
Is it the weekend?
Entry
Yes
No
Actions
Get up
Stay in bed
Entry
X
9. Abdisalam Issa-Salwe, Thames Valley University
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Conditions
Is it 8 o’clock yet?
Is it the weekend?
Entry
Yes
No
Actions
Get up
Stay in bed
Entry
X
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Conditions
Is it 8 o’clock yet?
Is it the weekend?
1 2 3 4
Actions
Get up
Stay in bed
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Conditions
Is it 8 o’clock yet?
Is it the weekend?
1 2 3 4
Y Y N N
Y N Y N
Actions
Get up
Stay in bed
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Conditions
Is it 8 o’clock yet?
Is it the weekend?
1 2 3 4
Y Y N N
Y N Y N
Actions
Get up
Stay in bed
X
X
X X
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Decision table (cont...)
Advantages:
Information is presented through a table
in an easy to modify format. Decision
table systems correspond with known
design techniques.
Disadvantages
Sequence information is implicit
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Developing testing strategy
Strategy approach
To be formulated that the details approach
that will be taken to testing, including the
tests to be conducted and the testing
tools/techniques that will be used
Test plan:
A test plan should be developed that
state:
What will be tested
When it will be tested (sequence)
The test environment
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Limitation
Poor testing process:
The test plan may not cover all area of
system functionality
Inadequate time:
Software and systems are inevitable
produces under significant time pressure
Future requirements not anticipated:
The test data used may have been fine at
the time of testing, but future demands
may be outside the range of values tested
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Limitation (cont…)
Software changes inadequate tested:
System/software changes made as a
result of testing findings or for other
reasons may not be adequately tested as
they were not in the original test plan