Moving away from legacy code (AgileCymru)

Moving away from legacy code

with BDD

BDD Practice Manager

Creator of Behat - Cucumber for PHP

Software Engineer turned Stakeholder whisperer

KonstantinKudryashov

@everzet

This talk is about

• Solving purely technical “TCIAM” problem using behaviour driven development practices and agile discovery processes

• Planning a delivery strategy on the basis of change appreciation

• Real-life experience

Legacy projects

How most teams see their next project

our next project

our next project

their actual next project

Agile, TDD, BDD, etc… // TODO: refactor later

Is it really that bad?

If a project can afford a salary of an engineer concerned about the project state,

then the project state is not that bad.

// TODO: refactor later



This world is full of brilliant projects that nobody is concerned about. Sadly, it’s often because

there’s no one left to care.

You deliver valueJust not as effectively as you could

Great value + Awful code = Great product yesterday


Great value + Great code = Great product tomorrow



No value + Any code = Awful product anytime


No value + Any code = Awful product anytime



// TODO: refactor laterAgile, TDD, BDD, etc…

Rewrite all the things!

learning

learning

trash bin

else

learning • Agile • XP • BDD

trash bin

else


trash bin

else


trash bin

else

Working system

1 year later…

nearly working system

how come?


trash bin

else


trash bin

else

legacylegacy

legacylegacy

shiny new

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shiny new

£Alegacylegacy

U

my features!!!

shiny new

£Alegacylegacy

shiny new

£A

U

my features!!!

legacylegacy

shiny new

£A + £B

U

my features!!!

legacylegacy

shiny new

£ U

my features!!!

£A + £B

my opportunities!!!

legacylegacy

shiny new

£ U

my features!!!

£10,000/m

£A + £B

my opportunities!!!

legacylegacy

shiny new

£ U

my features!!!

£10,000/m £10,000*x

£A + £B

my opportunities!!!

legacylegacy

shiny new

£ U

my features!!!

£A + £B

my opportunities!!!

legacylegacy

£A + £B

£ U

my features!!!

shiny new

my opportunities!!!

legacylegacy

shiny new

£A + £B + £C

my opportunities!!!

£ U

my features!!!

legacylegacy

my opportunities!!!

£

shiny new

£A + £B + £C*?

my opportunities!!!

£ U

my features!!!

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my opportunities!!!

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my opportunities!!!

£

it does not work!Well, not always...

Why do legacy projects suck?

Cost

Time

cost of change

How do we balance the cost of change?

Cost

Time

cost of ownership

Cost

Time

cost of ownership

Cost

Time

cost of changecost of ownership

Cost

Time

rewrite

take ownership only when you need to support change

… Of change where?

Innovation Predictability



Constant change, never ideal

Rarest change, good is good enough

Questionnaire

1. Where is this product going?

2. Which features need to change?

3. How are they going to change?

4. How to support that change?

“BDD Pipeline”


2. Which features need to change?

3. How are they going to change?


• Impact Mapping

• Value Prioritisation

• Example (3 Amigos) Workshop

• BDD layers


Impact Mapping

– Gojko Adzic

“Impact mapping is a strategic planning technique that prevents organisations from getting lost

while building products and delivering projects, by clearly communicating assumptions, helping teams align their activities with overall business objectives and make better roadmap decisions.”

Four levels of Impact Map

1. Why? are we doing all this (rewrite)? What is the goal we’re trying to achieve?

2. Who? will be impacted by it?

3. How? can they help us to achieve the goal?

4. What? can we do to support them?

MVP

Product Backlog

In order to buy more products As a customer I need to have a product autocompletion in the search field

2. Which features are going to change?

Value Prioritisation

In order to maintain my shopping history As a site visitor I need to be able to register on this site

In order to maintain my shopping history As a site visitor I need to be able to register on this site

benefit

actor

SELECT s.* FROM backlog as s ORDER BY s.role, s.benefit LIMIT 25

3. How are these features going to change?Example (3 Amigos) workshops

Three layers of a User-Story

• Business rule(s)

• Communication

• Acceptance criteria

Three layers of a User-Story

• Business rule(s)

• Communication in Examples

• Acceptance criteria

In order to keep track of stock As a store owner I want to add items back to stock when they are returned

Feature: Returned items go back to stock

Scenario: Refunded items should be returned to stock



Scenario: Replaced items should be returned to stock




Scenario: ...





Scenario: ...

Scenario: ...

Scenario: ...

Scenario: ...

Scenario: ...





Given a customer previously bought a black sweater from us And we currently have three black sweaters left in stock When customer returns the sweater for a refund Then we should have four black sweaters in stock








Given a customer previously bought a black sweater costing 15$ from us And we currently have three black sweaters left in stock When customer returns the sweater for a refund Then we should have four black sweaters in stock And customer account should be debited with 15$

Step#1: Identify change area

Step#2: Identify old logic

Step#3: Discuss old logic

1. What should this thing do

2. What if it suddenly stops doing it?

3. How would you know if it doesn't work?

4. How would you know if it does?





Scenario: Cost of refunded item should be returned to customer bank account

Scenario: Cost of refunded item should be returned to customer PayPal account

Scenario: Cost of refunded item should be returned to customer via in-shop credits





@legacy Scenario: Cost of refunded item should be returned to customer bank account

@legacy Scenario: Cost of refunded item should be returned to customer PayPal account

@legacy Scenario: Cost of refunded item should be returned to customer via in-shop credits





Step#4: Prepare for A change

1. Cover old behaviour in an end-to-end fashion

2. Make sure that scenarios/tests are green

3. Refactor code to make the lower testing possible

4. Convert scenarios/tests to lower level tests

Step#5: Make a change

1. Automate new scenarios

2. Make scenarios green by applying BDD loops

Stories

Examples

Describe

ImplementDesign

Working system

1 year later…

Same ashtrays, better system

Stop dreaming of a greater code

Find a way to deliver a greater value

We do that for clientsAnd help others to do it

http:// .com

Thank you!

@everzet

Technology

Moving away from legacy code (AgileCymru)