From Jurassic Park to Microservices

prepare for…
From Jurassic Park…
..to Microservices….

@SvenRuppert
has been coding java since 1996
Fellow / Head of R&D
reply Group
Germany - Munich
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@SvenRuppert
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@SvenRuppert
Projects in the ﬁeld of:
•Automobile-industry
•Energy
•Finance / Leasing
•Space- Satellit-
•Government / UN / World-bank
Where?
•Europe
•Asia - from India up to Malaysia
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Save harbor statement
The following is intended for information purposes only. I
can not be held responsible for the overuse of effects and
animations in this presentation. If any person in this room
has a medical condition that is triggered by fast moving
objects on the screen and/or explosions, he/she should
probably better leave now…
(I got carried away by the topic.)

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@SvenRuppertAt the time I started - 3 yrs ago

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Codebase is > 13 years old

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no test coverage

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no test coverage
Code Lords

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no test coverage
Code Lords
nearly 15% are retired soon

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no test coverage
Code Lords
over 50% are since 15 yrs in the company

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no test coverage
Code Lords
hiring only students

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no test coverage
Code Lords
the developers learned Java at this project

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no test coverage
Code Lords
the developers learned Java at this project
the ﬁrst feeling was like ……

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@SvenRuppertOverview
The Team
The Knowledge - Sharing
The way of working
The way of leading the Team
QM / QS - How to increase quality
Technical Migration?

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@SvenRuppertOverview - Start Small

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@SvenRuppertOverview - Think Bigger

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@SvenRuppertOverview - Build a Team

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@SvenRuppertOverview - Trust

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@SvenRuppertThe way of working
20% Time have time to play or try
start learning how to practice it ?
Closed Source versus Open Source
work from everywhere at your time
we started step by step

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@SvenRuppertwork from everywhere

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change your environment

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use Messenger like Slack

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use Messenger like Slack avoid mails

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remote meetings with zoom

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remote Pair-Programming

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work async.

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work async.
work at your time that is the best for you

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my „normal“ day…

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working05AM to 07AM

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working05AM to 07AM
breakfast with the family07AM to 09AM

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working05AM to 07AM
working09AM to 12AM

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working05AM to 07AM
working09AM to 12AM
playing with my son12AM to 07PM

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working05AM to 07AM
working09AM to 12AM
playing with my wife07PM to 09PM

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working05AM to 07AM
working09AM to 12AM
working09PM to 11PM

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working05AM to 07AM
working09AM to 12AM
working09PM to 11PM
and yes… I need only 6h sleep ;-)

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working05AM to 07AM
working09AM to 12AM
working09PM to 11PM

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working05AM to 07AM
working09AM to 12AM
working09PM to 11PM
working with Asia

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working05AM to 07AM
working09AM to 12AM
working09PM to 11PM
working with Asia
working with Europe

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working05AM to 07AM
working09AM to 12AM
working09PM to 11PM
working with Asia
working with Europe
working with US

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20% Time

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why you should do it?20% Time

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why you should do it?20% Time
lost in daily business

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20% Time

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how to make it useful ?20% Time

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how to make it useful ?
for the developer
20% Time

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for the developer
for the company
20% Time

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example : POC in the Mountains
for the developer
for the company
20% Time

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@SvenRuppertClosed- versus Open Source

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Analyzing the existing Code

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in our case : a lot of infrastructure…

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..with this we are not earning money

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we divided the

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we divided the
code base

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we divided the
code base
dev. environment

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we divided the
code base dev. environment

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we divided the
discuss at conferences

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we divided the
could write articles about it

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we divided the
will lead to better documentation

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we divided the
out of company rules

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we divided the
free choice of tools

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we divided the
free choice of tools
higher motivation

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Start Learning again

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for example:

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for example:
focus on a new paradigm

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for example:
functionalfocus on a new paradigm

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for example:
functionalfocus on a new paradigm reactive

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for example:
functional
add a new Language
focus on a new paradigm reactive

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for example:
functional
add a new Language
but not everyone want to learn
reactive

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for example:
functional
add a new Language
or better…. some are learning faster
reactive

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for example:
functional
add a new Language
or better…. some are learning faster
reactive
this sometimes leads to …..
reactions….

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this sometimes leads to ….. reactions….

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running away

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expecting something

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feeling the near end

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or only
feeling to old

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if you don´t want
to loose them

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you have to deal with this
if you don´t want
to loose them

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if you don´t want
to loose them
make them
happy again

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if you don´t want
to loose them
make them
happy again
How we solved
this?

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we are a product company

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with a lot of LTS contracts

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we created three streams

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Consultants - play and throw away

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Core Developers - collect and clean

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LTS Developers - keep alive

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LTS Developers - keep alive
Why ?

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Core Developer - collect and clean
LTS Developer - keep alive Why ?

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some want to learn and experiment

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some need more stabil environments

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some did not want to change something

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LTS Developer - keep alive
Why ?

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Why ?
amount of hours paid by the customer

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Why ?
rated on hours the systems are stabil

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Why ?
rated on hours the systems are stabil
ﬁxed income - bonus based on Change Request

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customer driven

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SCRUM
customer driven

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SCRUM
customer driven
roadmap driven

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SCRUM
Kanban
customer driven
roadmap driven

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SCRUM
Kanban
Consultants
LTS - Developers
Core - Developers Core - Developers
Consultants

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SCRUM
Kanban
Consultants
LTS - Developers
Fire
Consultants

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SCRUM
Kanban

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SCRUM
Kanban
LTS - Developers LTS - Developers LTS - Developers

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SCRUM
Kanban
Consultants
LTS - Developers
Consultants Consultants Consultants
LTS - Developers LTS - Developers

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SCRUM
Kanban
Consultants
LTS - Developers
time based planning

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SCRUM
Kanban
Consultants
LTS - Developers
Core - Developers
time based planning

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SCRUM
Kanban
Consultants
LTS - Developers
Core - Developers
time based planning
version based

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SCRUM
Kanban
Consultants
LTS - Developers
Core - Developers
time based planning ﬁxed size time slots
version based

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SCRUM
Kanban
Consultants
LTS - Developers
Core - Developers
time based planning ﬁxed size time slots
version based dynamic size time slots

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@SvenRuppertKnowledge Sharing
Consultants
LTS - Developers
Core - Developers

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Consultants
LTS - Developers
Core - Developers
build a source of knowledge

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Consultants
LTS - Developers
Core - Developers
Hacking session
Articles / Blogs
Screencasts
Refactoring Sessions
POC

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@SvenRuppertTechnical Migrations

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if you ask the consultants…

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to scale or change you need at least … ;-)

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NoSQL

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NoSQL Akka / Scala

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NoSQL
Events
Akka / Scala

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NoSQL
Events
Akka / Scala
Reactive

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NoSQL
Events
Akka / Scala
Reactive
Functional

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NoSQL
Events
Akka / Scala
Reactive
Functional
maybe ;-)

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@SvenRuppertTechnical Transformation

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JDBC - ResultSet

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JDBC - ResultSet Speedment - Streams

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Swing

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Swing Vaadin

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Swing Vaadin
HashMap

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Swing Vaadin
HashMap Hazelcast - Map

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Swing Vaadin
what is the right technology for your team?

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Swing Vaadin
what is the right order?

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reduce complexity

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reduce complexity
the team could work with

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reduce complexity
scale

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reduce complexity
scale
a lot more….

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reduce complexity
scale
a lot more….
start with new modules ?

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reduce complexity
scale
a lot more….
start with the oldest one ?

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reduce complexity
scale
a lot more….
most komplex one?

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reduce complexity
scale
a lot more….
most komplex one?
… or ….

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on thing that would limit your speed…

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time

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time
number of versions

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time
number of versions
v1

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time
number of versions
v1
v2

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time
number of versions
v1
v2
stabilize

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time
number of versions
v2
stabilize

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time
number of versions
v2
stabilize
delta t compared
to project lifetime

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@SvenRuppertQM / QS - TDD
Do you have bugs in your code ?

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no

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since years
you are
working hard
on this….
no

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remember….
how to start?
what is the right point to start?
how to increase the quality of the tests?

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no test coverage
remember….
how to start?

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no test coverage
how to decrease complexity?
remember….
how to start?

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TDD with jUnit @SvenRuppert

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are you using jUnit?

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assume that the following would make sense.. ;-)

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public class Service { 
public int add(int a, int b){ 
if(a<2){ 
return (a+b) * -1; 
} else { 
return a+b; 
} 
} 
}

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if(a<2){ 
} else { 
return a+b; 
} 
} 
}
How many tests
you will need ?

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if(a<2){ 
} else { 
return a+b; 
} 
} 
}
How many tests
you will need ?
it depends ;-)

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if(a<2){ 
} else { 
return a+b; 
} 
} 
}
How many tests
you will need ?
it depends ;-)

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if(a<2){ 
} else { 
return a+b; 
} 
} 
}
How many tests
you will need ?
it depends ;-)
for line 100% coverage

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if(a<2){ 
} else { 
return a+b; 
} 
} 
}
How many tests
you will need ?
it depends ;-)
for line 100% coverage 2

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if(a<2){ 
} else { 
return a+b; 
} 
} 
}
How many tests
you will need ?
it depends ;-)
but will this be enough?

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if(a<2){ 
} else { 
return a+b; 
} 
} 
}
How many tests
you will need ?
it depends ;-)
but will this be enough? maybe ;-)

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if(a<2){ 
} else { 
return a+b; 
} 
} 
}
How many tests
you will need ?
it depends ;-)

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if(a<2){ 
} else { 
return a+b; 
} 
} 
}
How many tests
you will need ?
how to ﬁnd out, what will be enough?
it depends ;-)

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if(a<2){ 
} else { 
return a+b; 
} 
} 
}
How many tests
you will need ?
how to ﬁnd out, what will be enough?
how to ﬁnd the right tests?
it depends ;-)

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if(a<2){ 
} else { 
return a+b; 
} 
} 
}
How many tests
you will need ?

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if(a<2){ 
} else { 
return a+b; 
} 
} 
}
How many tests
you will need ?
@Test 
public void testAdd001() throws Exception { 
final int add = new Service().add(0, 0); 
Assertions.assertThat(add).isEqualTo(0); 
}

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if(a<2){ 
} else { 
return a+b; 
} 
} 
}
How many tests
you will need ?
@Test 
}
@Test 
}

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Mutation Testing @SvenRuppert

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Mutation Testing is a structural testing method

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we want to ﬁnd a way to write "good" tests

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how to ﬁnd "good" tests?

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let the machine ﬁnd the targets

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let the machine ﬁnd the targets
let´s mutate it... but how?

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Mutation Testing - the Idea @SvenRuppert

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a mutation is a small change in the code

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.. small enough to be a small defect

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P will be the program

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T will be the collection of all tests / Test Suite

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we will create a sequence of mutations / P1,P2,P3...

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.. Px will have only one mutation compared to P

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running all tests from T against Px

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green: T will kill the mutation

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.. at leased one test from T will fail

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.. at leased one test from T will fail
red: if all tests are green

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if we kill k out of n mutants

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-> we are not good enough ;-)

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we are perfect enough if we are reaching : k == n

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how to create all versions of Px ?

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.. the good thing..

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.. the good thing..
we could almost generate/
automate everything

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practical TDD with Mutation Testing

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generating the mutants and

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running all junit tests

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check the reports

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check the reports
write more / better tests

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check the reports
write more / better tests
loop until quality target reached

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Mutation Testing - Hello World @SvenRuppert
public class Service {
public int add(int a, int b){
if (a<2) {
return (a+b) * -1;
} else {
return a+b;
} 
} 
}

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if (a<2) {
return (a+b) * -1;
} else {
return a+b;
} 
} 
} how many test you will need for..

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if (a<2) {
return (a+b) * -1;
} else {
return a+b;
} 
} 
100% Line Coverage… and…

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if (a<2) {
return (a+b) * -1;
} else {
return a+b;
} 
} 
100% Line Coverage… and… to be save ?

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if (a<2) {
return (a+b) * -1;
} else {
return a+b;
} 
} 
2 for Line Coverage

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if (a<2) {
return (a+b) * -1;
} else {
return a+b;
} 
} 
2 for Line Coverage we will see ;-)

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if (a<2) {
return (a+b) * -1;
} else {
return a+b;
} 
} 
}

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if (a<2) {
return (a+b) * -1;
} else {
return a+b;
} 
} 
}
we have one if statement

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if (a<2) {
return (a+b) * -1;
} else {
return a+b;
} 
} 
}
we have one if statement with an else branch

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if (a<2) {
return (a+b) * -1;
} else {
return a+b;
} 
} 
}
we have one if statement with an else branch
this will lead to 2 jUnit Tests to get 100 %

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if (a<2) { return (a+b) * -1; }  
else { return a+b; } 
} 
} 100% Line Coverage… and…

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if (a<2) { return (a+b) * -1; }  
} 
@Test 
}

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if (a<2) { return (a+b) * -1; }  
} 
@Test 
}
@Test 
}

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Assertions.assertThat(add).isEqualTo(0);
Assertions.assertThat(add).isEqualTo(3);

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final int add = new Service().add(0, 0);
>> Generated 54 mutations Killed 3

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>> Generated 54 mutations Killed 3

Killed 3
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>> Generated 54 mutations

Killed 3
57

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Killed 4
57

Killed 4
58

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Killed 5
58

Killed 5
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killed 9:1

Killed 5
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killed 9:1

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killed 9:1

Killed 6
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killed 9:1

Killed 6
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killed 11:1

Killed 6
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Mutation Testing - in short words @SvenRuppert

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mutation testing is an add on to normal jUnit TDD

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tools are supporting it well

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generating and running all tests are time consuming

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but most important

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but most important
will eﬀect your project structure

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Mutation Testing - Lesson Learned @SvenRuppert

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mutation tests are often leading to

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mutation tests are often leading to
…cleaner code compared to jUnit only

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public static ﬁnal String[] discardCommonPreﬁx(String a, String b) {
String[] ret = { a, b };
int l = a.length() < b.length() ? a.length() : b.length();
for (int i = 0; i < l; i++) {
if (a.charAt(i) == b.charAt(i)) {
if (i + 1 < l) { ret[0] = a.substring(i + 1); ret[1] = b.substring(i + 1); }
else {
if (a.length() < b.length()) { ret[0] = ""; ret[1] = b.substring(i + 1); }
if (a.length() == b.length()) { ret[0] = ""; ret[1] = „"; }
if (a.length() > b.length()) { ret[0] = a.substring(i + 1); ret[1] = „"; }
}
} else break;
}
return ret;
}

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public String[] discardCommonPrefix(String a, String b) {
final String[] ret = new String[2];
int l;
if (a.length() < b.length()) { l = a.length(); }
else { l = b.length(); }
int position = 0;
for (; position < l; position++) {
final char charA = a.charAt(position);
final char charB = b.charAt(position);
if (charA != charB) { break; }
}
if (position >= a.length()) { ret[0] = ""; }
else { ret[0] = a.substring(position); }
if (position >= b.length()) { ret[1] = ""; }
else { ret[1] = b.substring(position); }
return ret;
}

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Version 1 Version 2

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Version 1 Version 2
for {
if {
if
else {
if
if
if
}
} else
}

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Version 1 Version 2
for {
if {
if
else {
if
if
if
}
} else
}
if else
for {
if
}
if else
if else

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Example of useless Code @SvenRuppert

Summary
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@SvenRuppert
Now it is time to relax again ;-)

Summary
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@SvenRuppert
If you are interested…
have a look at GITHUB
ProxyBuilder
Dynamic-Dependency-Injection
Java-Microservice
or contact me ;-) @SvenRuppert

Summary
68
@SvenRuppert
If you are interested…
have a look at GITHUB
ProxyBuilder
Dynamic-Dependency-Injection
Java-Microservice
or contact me ;-) @SvenRuppert
Thank You !!!

From Jurassic Park to Microservices

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