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1. September 2007
Neil Thompson
SoftTest Ireland with the support of the All Ireland Software Network
Belfast 20 Sep 2007
Thinking tools:
from top motors, through
software process improvement, to
context-driven
Neil Thompson Thompson information Systems Consulting Ltd
23 Oast House Crescent
Farnham, Surrey
England, UK
GU9 0NP
www.TiSCL.com
©

2. September 2007
Can software process improvement learn Neil Thompson
from these?
TOYOTA PRIUS
©
2
TOYOTA CELICA GT4

3. September 2007
How Toyota progressed through quality to Neil Thompson
global dominance, and now innovation
• Quality (top reputation):
– has dominated JD Power satisfaction survey for decade
– Toyota Production System (TPS): 14 principles across
Philosophy, Problem-Solving, Process and People &
Partners
• Global dominance:
– market value > GM, Chrysler & Ford combined
– on track to become (2006) world’s largest -volume car mfr
• Innovation (fast):
– Lexus: invaded the “quality” market and won
– Prius: not evolutionary but revolutionary – and launched 2
months early and sold above expectations
– Toyota Product Development System (TPDS):
13 (!) principles across Process, People and
Tools & Technology ©
3

4. September 2007
Neil Thompson
Agenda
• Contents:
– Analogies between world -leading improvements in manufacturing and
what we may do in the software development lifecycle (SDLC):
• 1. Things that flow through a process: inventory, value (EuroSP3 2004)
• 2. Constraints on process, and thinking tools to improve (EuroSTAR 2006)
• 3. From process improvement to process definition, eg context-driven
(STAREast 2003)
• Acknowledgements:
– Jens Pas (EuroSTAR 1998) – my introduction to Goldratt
– Greg Daich (STAREast 2002) – I generalised his idea, then worked
backwards to the roots
• Objectives for audience:
– entertainment? – something a bit different
– appreciate some fundamental principles
– take away a set of simple diagrammatic thinking tools which are useful
in many situations
– think about your particular SDLC – where are the constraints?
– go on to read some of the references
– benefit by then improving your own processes
– be more ready to learn from other disciplines & industries ©
4

5. September 2007
The “new” paradigm in manufacturing: value Neil Thompson
flow, pull not push, problem-solving
TPS & TPDS TOYOTA: GOLDRATT:
• Customer-defined value 3. Pull to avoid Takt (rhythm), Drum-
(to separate value -added from waste) over-production Low-Inventory (“lean”), Buffer-
4. Level workload
Just-In-Time Rope
Minimise waste Maximise throughput
2. Continuous process flow to surface problems Andon (stop and fix) Critical Chain manag’t
7. Visual control to see problems Kanban cards
Tagging slow movers Monitoring buffers
One-page metrics
12. See for yourself to thoroughly understand Chain of 5 “why”s Cause-effect trees
Conflict resol diagrams
14. Learning org via reflection & improvement Plan-Do-Check-Act Identify constraint,
“elevate” & iterate
• And now these principles have been successfully applied
beyond actual manufacturing, into product development
• But what about development of software?...
13. Decide slowly (all options) by consensus • Front-load product dev to explore thoroughly
alternatives while max design space
©
• I prefer Goldratt for thinking tools... 5

6. September 2007
Goldratt’s Theory of Constraints: an analogy Neil Thompson
to explain
Goal: to win the war
Objective: to maximise throughput (right soldiers doing right things)
Constraint on throughput: slowest marcher
Drum Rope
Buffer
diagram based on those in “The Race”,
E.M. Goldratt & R. Fox 1986
Critical chain: weakest link is all we need fix, by means of...
Five focussing steps: identify constraint, exploit it, subordinate all else,
elevate it (i.e. strengthen so not now weakest), then... identify next constraint
But now it’s no longer simple: so need iterative tools for:
what to change, what to change to, how
Five thinking tools (based on sufficient causes & ©
necessary conditions) 6

7. September 2007
Neil Thompson
Applicability of TOC beyond manufacturing
• Military logistics
• Marketing, sales & distribution
• Project management
• Measurements, human relationships, medicine etc
• Using technology, eg assessing benefits of functionality
• IT systems development:
– focussing of Goldratt’s Critical Chain on hi-tech projects
Robert C Newbold
– methodology design Alistair Cockburn
– “Lean software development” Mary & Tom Poppendieck
– Agile management using Feature Driven Development David
J Anderson
©
7

8. September 2007
Neil Thompson
But software development isn’t
like manufacturing?
• Software isn’t like hardware
• Intellect adds value less predictably than machines
• The manufacturing part of software development is disk
duplication: “development” is really a design activity
• People are more important than processes
• Software development doesn’t repeat exactly, people are
always tinkering with the processes
• Development involves discovery, production involves
reducing variation
• But I say: does that make all the analogies worthless,
or do they just need interpreting? I suggest the latter…
©
8

9. September 2007
Neil Thompson
A code factory and a bug factory
• No-waste factory
a b c Stated Demonstrations &
requirements acceptance tests
Programming
• Now here’s some waste: meeting/escalation (and
loaded personal memories), or inventory?
a b c a b’ d Implicit
requirements
Documented
? Acceptance tests
I
I
requirements
?
Meeting / escalation to agree
Programming
©
9

10. September 2007
Neil Thompson
Specs & unfinished software are inventory
• Specifications are generally not needed after go-live (I will come
later to exceptions) so they are not end -product, they are work-in-
progress (especially intermediate levels like functional & non-
functional specs)
• Untested software, and even finished software not paid for, is a lso
inventory
• Iterative lifecycles help if “adaptive” (product-based) rather than
“transformational” (where specifications multiply!)
a b Revised & new requirements
a’ b’ c
I
May include
Programming Programming
redesign
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10

11. September 2007
The full traditional W-model bulges with Neil Thompson
inventory!
Business
objectives
Test against Post-implement -
Make
into Verify ation review
Requirements Verify & Validate Acceptance Acc. retest,
Statement RS, + spec. AT test fix & reg. test
Validate
(incl.
“QA”) Functional Verify & Validate System Sys. retest,
Spec. FS, + spec. AT test fix & reg. test
Retest lower
Technical V&V TD, Integrat- Int. retest, levels
+ spec. IT fix & reg. test where
Design ion test necessary
Module V&V MS, + Unit Unit retest,
Specs. spec. UT test fix & reg. test
Code
Static-check
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11

12. September 2007
Neil Thompson
In a factory, small batches reduce inventory
Stages &
units / hour (i) 1.3
(ii) 10.0
Multi-batch
1000 (iii) 1.0 200 200 200 200 200
(ie “iterative”)
Single-batch
(ie “waterfall”) (iv) 10.0
(v) 2.0
0 1 2 3 4 0 1 2 3 4
months months
Inventory Inventory
Based on Goldratt, The race (North River Press 1986)
©
12

13. September 2007
Neil Thompson
Drum-buffer-rope approach to constraints
• Optimise throughput by:
– (1) drumbeat based on constraining stage (a) & orders (b)
– (2) buffer to protect constraining stage from upstream
disruptions
– (3) rope to prevent leader extending gap on constraining
stage
• For subassemblies feeding in, have additional buffers
“troops marching” materials flow
buffer
raw materials (1)
in constraining
”leader” stage (a) assembly
(2)
(3) buffer
subassembly orders (b)
©
13

14. September 2007
In software development & testing, small Neil Thompson
batches = agile methods: consider inventory
moving through SDLC
Amount of
functionality Requirements Inventory in
this stage Lead time for
Specification of process
this stage
Design
of process
Inventory in
process
overall Programming & Within each stage
unit testing of testing, can
Integration subdivide by
testing pass/fail,
bug states etc
System
testing
Acceptance
testing
Live and
paid-for
Date
If lines not approx parallel, inventory is growing
©
14
Based on Anderson, Agile management for software engineering (Prentice Hall 2004)

15. Agile methods: pull value instead of pushing September 2007
Neil Thompson
documentation
LEVELS OF DOCUMENTATION,
pushed by specifiers FLOW OF FULLY-
WORKING SOFTWARE,
pulled by
customer demand
+ Test Specifications
Requirements Accepted
System-
tested
+ Func
Spec
Integrated
+ Technical
Design WORKING
SOFTWARE
Unit / Component -tested
+ Unit / Component
specifications
©
15

16. September 2007
Neil Thompson
But even if our context is not suitable (or ready)
for agile methods, we should understand flow
raw materials
in Where is/are the
Requirements
constraining stage(s)?
Where should buffers
Specification
be / not be? Acceptance
order(s )
testing
System
testing
Design assembly
Integration
testing sub-assemblies
Programming Unit
testing
©
16

17. September 2007
New paradigm problem-solving: the Goldratt- Neil Thompson
Dettmer* “Thinking Tools”
What to
........... What to change to .......
change (1) (2) (3)
Core problem+ Prerequisites+ CURRENT REALITY
(other) Root causes Conflicts + Injections
Intermediate Intermediate FUTURE
Requirements +
effects effects
INJECTIONS REALITY
Undesirable Desired
Objective
effects effects
CURRENT CONFLICT .... How to change ....
REALITY RESOLUTION (4) Intermediate Needs+ (5)
objectives Specific
actions
* very slightly paraphrased here
Obstacles Intermediate
effects
PRE- TRANS-
REQUISITES Objective Objective ITION
Sources: Dettmer, W. Goldratt’s Theory of Constraints (ASQ 1997)
Thompson, N. “Best Practices” & Context-Driven – building a bridge (StarEast 2003)
©
17

18. September 2007
The thinking tools are complementary diagrams Neil Thompson
http://www.osaka-gu.ac.jp/php/nakagawa/TRIZ/eTRIZ/eforum/eETRIACon2003/Fig11TillmannB.jpg
• Causes and effects
©
• Necessary and sufficient conditions 18

19. September 2007
Why better than “traditional” process Neil Thompson
improvement in software testing
Test
J Some
Lanalogies
Medical
flexibility
Organisation
MaturityTM
MATURITY
LEVELS
Test
Maturity
ModelSM
PREDEFINED SUBJECT AREAS
Test
Process
Sources: Improvement ®
TMMSM - http://www.stsc.hill.af.mil/crosstalk/1996/09/developi.asp
TPI® – based on http://www.sogeti.nl/images/TPI_Scoring_Tool_v1_98_tcm6 -30254.xls
TOMTM – based on http://www.evolutif.co.uk/tom/tom200.pdf, as ©
interpreted by Reid, S. Test Process Improvement – 19
An Empirical Study (EuroSTAR 2003)

20. September 2007
Neil Thompson
Extending the new paradigm to testing: by
rearranging TPI’s key areas…
1.Test strategy
2.Lifecycle model
3.Mom of involv’t
4.Estim & plan
5.Test spec techn
6.Static techn’s
7.Metrics
8.Test automation
9.Test env’t
10.Office env’t
11.Commit & motiv
12.Test func & train
13.Scope of meth’y
14.Communication
15.Reporting
16.Defect mgmt
17.Testware mgmt
18.Test proc mgmt
19.Evaluation
20.Low-lev testing
…we can begin to see cause-effect trees… ©
20

21. September 2007
Cause-effect trees: can start with TPI’s inbuilt Neil Thompson
dependencies
4.Estim & plan 6.Static techn’s 5.Test spec techn 7.Metrics
A:Substantiated A:Informal techniques A:Product for project
B:Formal techniques
3.Mom of involv’t 1.Test strategy 19.Evaluation 20.Low-lev testing 2.Lifecycle model 18.Test proc mgmt
A:Single hi-level test A:Plan, spec, exec A:Planning & exec’n
A:Compl test basis
B:+Monitoring &
adjustment
13.Scope of meth’y 14.Communication 11.Commit & motiv 12.Test func & train 16.Defect mgmt 15.Reporting
A:Budget & time
A:Internal A:Defects
A:Project -specific
B:Test int in proj org B:Progress , activities,
prioritised defects
A:Testers & Test Mgr
10.Office env’t 9.Test env’t 8.Test automation 17.Testware mgmt
A:Managed-controlled
A:Internal
…eg for getting to at least level A throughout ©
(slightly simplified) 21

22. September 2007
Can add extra “key areas”, lifecycle inputs & Neil Thompson
outputs, general categories
INPUTS & 4.Estim & plan + Risk-Based 6.Static techn’s 5.Test spec techn TECHNIQUES 7.Metrics
STAR
INFLUENCES in general
on testing
3.Mom of involv’t 1.Test strategy 19.Evaluation 20.Low-lev testing 2.Lifecycle model 18.Test proc mgmt
LIFECYCLE
in general
13.Scope of meth’y 14.Communication 11.Commit & motiv 12.Test func & train 16.Defect mgmt 15.Reporting
ORGANISATION
in general
10.Office env’t 9.Test env’t INFRA- 8.Test automation + Test data 17.Testware mgmt OUTPUTS
STRUCTURE from testing
in general
…eg TPI / TMap’s four “cornerstones” ©
22

23. September 2007
Can go beyond the fixed questions: SWOT Neil Thompson
each subject area Source:
solid borders denote as in TPI; dashed borders denote additional
INPUTS & INFLUENCES on STAR 4.Estimating & planning
STRENGTHS OPPORTUNITIES STRENGTHS OPPORTUNITIES
Some managers are
considering Monitored, and adjustments
agile methods made if needed
Business analysts may be
motivated by UML training
Too busy for well-considered
estimating & planning
System requirements are The most experienced
The squeeze on testing is
agreed too late business analysts are leaving,
likely to worsen
more may follow
Release dates are fixed
System specs & designs are
defective, just timeboxed
Can’t recruit more staff
System specs are heavy text
documents Not substantiated, just “we
did it as in previous project”
WEAKNESSES THREATS WEAKNESSES THREATS
©
(small Post-it® notes are good for this) 23

24. September 2007
Applying the thinking tools to information Neil Thompson
from SWOT analysis Using extracts from both 1 st & 2nd examples
STRENGTHS OPPORTUNITIES TACTICAL: Address culture by
worked examples of diagrams
Some managers are
considering
agile methods
(Use Strengths to help TACTICAL: Include tables &
diagrams in test specifications
Business analysts may be
amplify opportunities) motivated by UML training
ONGOING:
Techniques
training &
Action planning
Can still improve coverage coaching
at macro level with
informal techniques
STRATEGIC:
(80/20) Improve SDLC method TRANS-
CONFLICT FUTURE REALITY ITION
CURRENT REALITY RESOLUTION
PRE-
Culture of our testers is to
prefer large text documents
SDLC method does not
encourage diagrams
REQUISITES
to diagrams
System specs are heavy text
documents
(Use Threats to help Anticipating &
identify obstacles) overcoming
Test specs are large & “texty ”
obstacles
Test coverage omissions & overlaps
WEAKNESSES Too many failures in Live THREATS
The SWOT method can be “nested”, eg aggregate up
©
from individual subject areas to whole lifeycle 24

25. September 2007
Difficulties in problem-solving: Neil Thompson
conflict resolution (eg for documentation)
Agree in a “We need
workshop what
“If it’s not written, “Test reports need to “Reviews are powerful at more
documentation finding defects early, but it’s
is needed
it can’t be signed off” be formal documents”
difficult to review just speech”
documentation”
“What documentation is needed
“Sign-off can be by
for contractual reasons? Still agreed meeting outcomes” “Are there few enough people
time to negotiate?” Yes!
Documentation to make frequent widespread
doesn’t have to meetings practical?” No!
Objectives of be paper: use
documentation wikis etc
CONFLICT
Can mix
exploratory Documentation varies:
are to help build & scripted
need to distinguish necessary
Documentation from unnecessary
and maintain a is still needed testing
Make maximum
fit-for-purpose for maintenance
use of tables
after go-live Need to distinguish quality
system by knowing & diagrams of documentation, not
just quantity
and agreeing
what built and “They will when their
what tested memories have faded “Are test analysts writing “Will the live system be Our users cannot be on-site
or when there’s a maintained by its with the project throughout
tests for others to run?” No!
contract dispute” its developers?” No!
“Signed-off requirements
“People never read “Documented test plans Specifications are like are counterproductive to
any documentation” are counterproductive to inventory, no end value systems meeting real
“We need
the best testing”
user needs now” less
documentation”
Developed further to Daich, GT. Software documentation superstit ions (STAREast 2002) ©
See also Rüping, A. Agile documentation (Wiley 2003) 25

26. September 2007
Not only process improvement – we can apply Neil Thompson
the thinking tools to defining “appropriate” practices!
Always- Good What “appropriate” means
Context good practices in this context
principles in this REALITY + Injections
Root
“Prerequisites” context 3
causes
Intermediate
FUTURE
Extremes
Intermediate
Requirements effects REALITY
effects
Sub-requirements
(valid & invalid Desired
Effects effects
Objectives assumptions)
+ INJECTIONS
CURRENT 2a Questions to Choice categories
REALITY 1
POSITIONING
consider & actions
+ Justifications
5a Choice
• Methodology 2b Intermediate categories +
unhappy with CONFLICT sub-prerequisites NEEDS +
Specific
(à actions) RESOLUTION actions
INTERACTIONS
• Unsure how
best to test Obstacles Actions & sub-
(à conditions) 4 Intermediate objectives
effects
PRE- 5b
Sub-prerequisite
Objectives
© REQUISITES Sub- ©
26 objectives 26
TRANSITION

27. September 2007
This is a structure I argued could build a bridge Neil Thompson
between “best practices” and context-driven
Unifying points
Best
Practice “Always-Good”
Principles
Goldratt’s
“formalised “fossilised What How
“thinking tools”
sloppiness” thinking”
Constraints,
Context- Requirements,
Driven Objectives etc
Expert pragmatism
with structure ©
27

28. September 2007
1 Context (CURRENT REALITY) Neil Thompson
Business/ App type Corporate culture
org. sector Nation
QUALITY / RISK FACTORS
SCOPE, COST, TIME,
(eg USA) Technology
Legal Moral Job type & size:
• project/programme
constraints: constraints, eg: • bespoke/product
• regulation • human safety
• new/maintenance
• standards • money, property
• convenience
Process
Resources: constraints, eg:
• money (à skills, environments) • quality management
• time • configuration mgmt
• Unsure
how best Methodology
• Methodology
to test happy with
unhappy with
©
28

29. September 2007
2a Always-good principles Neil Thompson
(CONFLICT RESOLUTION upper level)
Always-good
Effectiveness
Efficiency
Risk management Quality management
Decide process targets Assess where errors originally made
& improve over time
Insurance Assurance Be pragmatic over quality targets
Plan early, then Define & use metrics
Give confidence (AT) rehearse -run, Use handover & acceptance criteria
Define & detect errors (UT,IT,ST) acceptance tests
V-model: what testing against W-model: quality management Use independent system & acceptance testers
Risks: list & evaluate Tailor risks & priorities etc to factors Use appropriate skills mix
l Refine test specifications progressively: Define & agree roles & responsibilities
Prioritise tests based on risks
l Plan based on priorities & constraints
l Design flexible tests to fit Use appropriate techniques & patterns
Define & measure
l Allow appropriate script format(s)
test coverage Use appropriate tools
l Use synthetic + lifelike data
Allow & assess for coverage changes Document execution & management procedures Optimise efficiency
Distinguish problems from change requests
Measure progress & problem significance Prioritise urgency & importance
Quantify residual risks & confidence Distinguish retesting from regression testing ©
29

30. September 2007
Neil Thompson
Conflicting interpretations of these principles
Next diagram will take each box from the previous diagram and as sess it on
a formal-informal continuum, so...
In preparation for this: what do we mean by “formality”?
• adherence to standards • consistency
and/or proprietary • contracted-ness
methods • trained-ness and
• detail certification of staff
• amount of • “ceremony”, eg degree
documentation to which tests need to
• scientific-ness be witnessed, results
• degree of control audited, progress
• repeatability reported
• any others?
©
30

31. September 2007
2b Neil Thompson
Good practices in this context
(CONFLICT RESOLUTION lower level)
We’re too • THEY ARE LEVELS, All systems are integrated from parts
Use a lazy to think
NOT STAGES
• SOME SPECS ARE
waterfall OUT OF DATE / IMPERFECT,
We want baselines to test against BUT WE COPE
V-model APPROPRIATE
We want to test viewpoints of: • NEED NOT BE 1-1 CORRESP USE OF
• users SPECS-LEVELS
• someone expert & independent
V-model:
• designers
• NEED NOT BE 4 LEVELS what testing
• programmers Two heads are better than one against
• MULTIPLE PARTIAL PASSES
“Conflict” We’re doing iterative development
Different levels
mitigate different risks
We’re doing adaptive development (no specs)
• CAN USE EXPLORATORY
Documentation must be minimised We have little time TESTING AGAINST
CONSENSUS BASIS
Don’t
We’re object-oriented • V-MODEL IS IMPLICIT IN BINDER’S BOOKTesting OO systems: models,
use a patterns & tools
V-model V-model is MANY PEOPLE We want to
discredited STAND BY V-MODEL be trendy, anyway
©
31

32. September 2007
3 What “appropriate” means in this context Neil Thompson
(FUTURE REALITY)
The system has:
• users
Our user requirements
• (potentially) expert & independent testers
are out of date and
• designers (where significant)
were vague when written
• programmers
We do have a good functional spec
and independent testers available
Our system is
very simple We do need separate
development & acceptance
V-model with
test levels
• NEED NOT BE 4 LEVELS only 3 levels:
We don’t need a l acceptance (v. consensus)
separate l system (v. spec)
integration test level l unit (informal)
Our programmers hate
documentation
©
32

33. September 2007
And so on… overall what we have done is Neil Thompson
deconstruct then reconstruct: the framework is a
“meta-V-model”
Choice
All possible CONFLICT RESOLUTION TRANSITION
categories
contexts upper upper
& actions
Your context CURRENT TRANSITION
REALITY Choices
lower
CONFLICT
Each practice PRE- Questions to
RESOLUTION
to examine REQUISITES consider
lower
FUTURE
FUTURE
REALITY
REALITY
What “appropriate” ©
33
means in your context

34. September 2007
Neil Thompson
Conclusions
• Summary:
– Toyota’s success (and penetration of Just In Time)
– “The Goldratt Trilogy”:
• 1. Things that flow through a process: inventory, value
• 2. Constraints on process, and thinking tools to improve
• 3. From process improvement to process definition, eg context-
driven
• Lessons learned:
– three papers are enough?
• Take away:
– read references – Dettmer is key
• Way forward:
– examples!
©
34

35. September 2007
Neil Thompson
Key references
• Context-Driven:
– Kaner, Bach & Pettichord (2002) Lessons learned in software testing, Wiley
• Best Practice:
– ISEB, ISTQB??
• My inspiration:
– Jens Pas (EuroSTAR 1998) Software testing metrics
– Gregory Daich (STAREast 2002) Software documentation superstitions
• Theory of Constraints understanding:
– Eliyahu M. Goldratt (1984 then 1992 with Jeff Cox) - The Goal; (1986 with R. Fox)
The Race; (1997) Critical Chain
• TOC overview and the thinking tools:
– H. William Dettmer (1997) Goldratt’s TOC: a systems approach to cont. improv’t,
ASQ
• Related (but differently-specialised) thinking from Agile
community:
– Alistair Cockburn: A methodology per project, www.crystalmethodologies.org
– Mary Poppendieck: Lean development: an agile toolkit, ©
35
www.poppendieck.com