Test Planning - Software Testing: Testing Across the Entire Software Development Life Cycle - page 89

do, these surface details will arrive in reverse order relative to the execution of the.
It is counter-intuitive to the way development planning occurs, but it works well for
testing. You can fi nd this relationship of development phases to test case writing,
and execution will be referenced in the literature as either the “V-diagram” or the
“bathtub diagram.” Figure 5.1 shows the bathtub diagram.

Development
phases

Test plan
and test cases

1

Preliminary
investigation
+ Analysis

Draft test plan
+ write test cases
for postimplementation

Update test plan
+ write test cases
for final construction
update test plan
+ write test cases
for preliminary construction

2

Design

3

4

Preliminary
construction

execute test cases
for preliminary construction

5

execute test cases
for final construction

Final
construction

6

Post
implementation

execute test cases
for implementation

Installation

Figure 5.1 The bathtub diagram

The left-hand side of the bathtub diagram represents development phases.
The right-hand side represents test planning, writing, and executing. The bathtub
diagram is read from top to bottom to follow the development life cycle. Please refer
to Chapter 4 to refresh your memory of the testing approaches expected for each
development phase.
Here are the relationships that the arrows show:

• Arrow 1 indicates that the development activities in Preliminary investi-

gation and Analysis produce enough information about the new applica-
tion that the test team can draft a test plan and write the test case for post-
implementation.
Arrow 2 indicates that the development activities in design produce enough
information about the new application that the test team can update the test
plan and write the test case for fi nal construction.
Arrow 3 indicates that later development activities in design also produce
enough information about the new application that the test team can update
the test plan and write the test case for preliminary construction.
Arrow 4 indicates that the development planning activities have been completed
and the development programming activities in preliminary construction have

•

•

•