C0 Testing

1
C0 Testing

• Instrumented code
• Output files (processed)
• Description of code not covered and why

2
SRC Comments final doc

• Comments are important and will be graded in the
  final documentation grading
• This will be subjective
• Guidelines
• Every class/function should have a description of
  purpose, internal data, inputs, outputs, author
• Every section should have brief description of
  purpose and algorithm (if not obvious)
• Points will be deducted for useless comments

3
Software Measurement

• quantifying software and
• software development

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Software Measures

• The purpose of software measures is to quantify
  characteristics of programs.
• Lord Kelvin is credited with claiming that a
  subject is not a science unless you can measure
  it.
• Unless we can measure characteristics of
  software, it will be very hard to develop a sound
  science of software engineering.

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Measurement

• the process by which numbers or symbols are
  assigned to attributes of entities in the real
  world in such a way as to describe them according
  to clearly defined rules

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Measurement Theory

• circa 1900 - applied to physics
• 1940s - applied to psychology, sociology
• 1990s - applied to software measurement

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Representational TOM

• empirical relation system
• (C,R)
• numerical relation system
• (N,P)
• M maps (C,R) to (N,P)
• representation condition
• xlty iff M(x)ltM(y)

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The Mapping

• The representation condition
• M(x) rel M(y) if x rel y
• x rel y iff M(x) rel M(y)
• Both have been used by classical measurement
  theory authors
• Fenton prefers the second definition

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Scales

• nominal
• ordinal
• interval
• ratio
• absolute

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McCabe's Complexity Measure

• also called the Cyclomatic Number
• introduced 1976
• one of the two or three most commonly used
  measures
• premise - complexity is related to control flow
  of the program

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Graph Theory

• the cyclomatic number
• minimal basis for describing any path in the
  graph
• not assumed to be complexity in graph theory

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Cyclomatic Number - arcs and nodes

• C e - n 2p
• where
• e number of edges,
• n number of nodes,
• p number of strongly connected components

TTYP1 what is e,n for triangle CFG? Assume
p1, what is cyclomatic number?
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CFG for triangle problem
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Euler (1707-1783)

• for planar graphs
• 2 n - e r
• where r number of regions, e number of edges,
  and n number of nodes
• 2 n - e r r e - n 2
• Therefore, the number of regions on a planar
  graph equals the cyclomatic number

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Cyclomatic Number - regions

• C r

TTYP2 label the regions on the triangle CFG
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Cyclomatic Number - decisions

• C Pi 1
• where Pi is the number of decisions

TTYP3 label the decisions on the triangle CFG
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Threshold

• McCabe analyzed a large project and discovered
  that for modules with complexity over 10, the
  modules had histories of errors and difficulties
  in maintenance

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Calculate McCabes cyclomatic
cin gtgt a gtgt b gtgt c if (a gt b) cout ltlt
hello if (c lt a)cout ltlt part 1 if ( c gt
b)cout ltlt part 2 else cout ltlt
part 3 elseif (clta)coutltltpart
4 cout ltlt exiting
TTYP4 draw the CFG and count e,n calculate
cyclomatic , label the regions and decisions
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Summary
McCabes cyclomatic number is not the
ultimate answer for complexity. It is a good
general indicator of relative size.
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Rest of Semester

• No more PLQs
• 11/28, 11/30, 12/5
• Security Presentations
• 12/7
• Review for 543 final
• Final Doc due Friday Dec 8th, 5pm
• Monday, Dec 11th 543 final 200-350