Page 218 - DCAP405_SOFTWARE_ENGINEERING

Unit 12: Testing Tactics

Notes
Example: Specifications state that a maximum of 4 purchase orders can be registered
against anyone product. The equivalence classes are: the valid equivalence class: number of
purchase orders is greater than or equal to 1 and less than or equal to 4 , also written as (1 < = no.
of purchase orders < = 4) the invalid class (no. of purchase orders> 4) the invalid class (no. of
purchase orders < 1)

3. If the requirements state that a particular input item match one of a set of values and each
case will be dealt with the same way, identify a valid class for values in the set and one
invalid class representing values outside of the set. For example, if the requirements state
that a valid province code is ON, QU, and NB, then identify : the valid class code is one of
ON, QU, NB the invalid class code is not one of ON, QU, NB.
4. If the requirements state that a particular input item match one of a set of values and each
case will be dealt with differently, identify a valid equivalence class for each element and
only one invalid class for values outside the set. For example, if a discount code must be
input as P for preferred customer, R for standard reduced rate, or N for none, and if each
case is treated differently, identify
the valid class code = P
the valid class code = R
the valid class code = N

the invalid class code is not one of P, R, N
5. If you think any elements of an equivalence class will be handled differently than the
others, divide the equivalence class to create an equivalence class with only these elements
and an equivalence class with none of these elements. For example, a bank account balance
may be from $0 up to $ 1,000,000, and balances $ 1,000 or over are not subject to service
charges. Identify:
the valid class: ($ 0 < = balance < $ 1,000) i.e., balance is between 0 and $ 1,000 - not
including $ 1,000
the valid class: ($ 1, 000 < = balance < = $ 1,000,000 i.e., balance is between $ 1,000 and
$1,000,000 inclusive

the invalid class: (balance < $ 0)
the invalid class: (balance> $ 1,000,000)
A definition of Equivalence Partitioning from our software testing dictionary:

Equivalence Partitioning: An approach where classes of inputs are categorized for product or
function validation. This usually does not include combinations of input, but rather a single
state value based by class. For example, with a given function there may be several classes of
input that may be used for positive testing. If function expects an integer and receives an integer
as input, this would be considered as positive test assertion. On the other hand, if a character or
any other input class other than integer is provided, this would be considered a negative test
assertion or condition.

Boundary Value Analysis

BVA extends equivalence partitioning by focusing on data at the “edges” of an equivalence
class.

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