Whitebox Testing

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Whitebox Testing

• CS2335
• Fall 2001

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Whitebox Testing

• AKA Structural, Basis Path Test
• Normally used at unit level
• Assumes errors at unit level are in the control
  structure or data path
• Generates test cases to test control paths
  through the code
• Criteria includes Control-Flow and Data-Flow
  based coverage

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Coverage Criteria

• Control Flow based
• Statement Coverage (All nodes)
• Branch (or Decision) Coverage (All edges)
• All Paths
• Data Flow based
• All DU paths
• All C uses
• All Defs
• Etc

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Motivation
What happens when good software goes bad? ATT
4ESS switch meltdown
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Unit Module Specification
Invoices are calculated using the following
algorithm Item X sells for 5 and Item Y sells
for 10 Invoice Total gt200 get 5 discount
Invoice Total gt1000 get 10 discount
Invoices that order more than 30 X items
get a 5 discount
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Example Program
int invoice (int x, int y) int d1, d2, s
if (xlt30) d2100 else d290 s5x 10
y if (slt200) d1100 else if (slt1000) d1
95 else d1 80 return
(sd1d2/10000)
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Statement Coverage
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Branch Coverage
9
Path Coverage
With loops impossible
6 Test Cases
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Data Flow Testing

• All du paths
• All u
• All c / some p
• All p / some c
• All d
• All p

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Some Definitions

• Definition-Use (sub)path wrt variable v such
  that DEF(v,m) and USE(v,n) and m, n are the
  initial and final nodes of the (sub)path.
• Definition-Clear (sub)path wrt variable v such
  that DEF(v,m) and USE(v,n) and not other node in
  the subpath is a DEF node for v

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Data FlowTesting
x, y, d1, d2, s
if
p
d d d d
1
sgt1000
xgt30
if
p
d
6
d
2
3
d
d
7
4
c c
d
sgt200
if
p
8
c c c
d
5
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Exercise 1
void handleCommandModeKeypress(char c) if
(c) startMulticharCommand( c ) else if
(cgt0 c lt9) doRepeatedCommand( c )
else switch(c) case x
doSingleCharDelete( ) break case
d doLineDelete( ) break
Generate Test Cases for Statement Branch
Paths
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Solution
C
Cgt0
Clt9
Cd
Cx
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Dataflow Solution
d
No new test paths??
p
p
p
c
p
c
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Dataflow Anomolies

• dd harmless, but suspicious
• kk possible bug
• kd normal
• ku bug
• -k possible bug
• -u bug

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Strength of Coverage
All Paths
All du Paths
All u
All c some p
All p some c
All d
All p
Branch
Statement
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How effective?
Strategy Mean Cases Bugs Found Random Testing
100
79.5 Branch Testing 34
85.5 All Uses
84
90.0
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Exercise 2
void doRepeatedCommand(char c) char
buffer256 int index0 int value 0
while (cgt0 clt9) bufferindexc
cgetch() bufferindex\0
valueatoi(buffer) for (index0indexltvaluein
dex) handleSingleCommand( c )
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Next Time
Specification-Based / Blackbox Testing
DEFECTUS ELIMINATO