Scaffolding a legacy app with BDD scenario (Agile in the City Bristol 2017)

Scaffolding a
legacy app
with BDD scenarios
using SpecFlow/Cucumber
Agile in the City Bristol 2017
2nd November, 2017
Gáspár Nagy
coach • trainer • bdd addict • creator of specflow
“The BDD Books: Discovery” • http://bddbooks.com
@gasparnagy • gaspar@specsolutions.eu

Copyright © Gaspar NagyCopyright © Gaspar Nagy
bdd addict
given.when.then
CAUTION!
on the stage
Gáspár Nagy
coach, trainer and bdd addict
creator of SpecFlow
gaspar@specsolutions.eu
https://specsolutions.eu
@gasparnagy

Check out our new book!
• A BDD book for everyone (PO, BA, dev,
tester)
• Practical guide
• Demonstrates good collaboration
techniques, illustrated by concrete
examples
Find it on Leanpub through
http://bddbooks.com!

Agenda
• BDD, how I see it
• Challenges of legacy apps
• Concept of scaffolding through an example
• Fixing a bug & placing it on the testing pyramid

What is BDD?

[HttpPost]
public ActionResult Answer(int answer)
{
TriviaEntities db = new TriviaEntities();
var question = db.FindQuestion(CurrentQuestion);
if (question.Type == QuestionType.Easy)
{
db.AddScore(question, user, 10);
}
else
{
db.AddScore(question, user, 50);
}
var model = new GameModel
{ Score = db.GetScore(question, user) };
return View(model);
}
implement
feedback
Agile mini-waterfall

Examples link requirements to software

Scenario: Correct easy answer scores 10
Given I register a team
When I submit a correct easy answer
Then my score should be 10
Discovery
Automation with
Cucumber/SpecFlow
Examples link requirements to software
Formulation

So, what is BDD?
Discovery
Shared understanding is established through
collaboration and structured conversations
Formulation
Examples of system behaviour are documented
as scenarios
Automation
Scenarios are automated to be able to verify the
system’s behaviour

BDD “drives” development
Passing
scenario
Failing
scenario
Refactor

The TDD Cycle
GreenRed
Refactor

How can I apply this
to legacy apps?

Working with a legacy app is like renovating a house…

Renovation can be challenging…
Source: http://kadarkocka.blogspot.com/2011_08_01_archive.html

My Story
The project was delivered in cooperation with TechTalk (www.techtalk.at)

My legacy app project…
Source: http://irodahaz.info

106 failing (integration?) tests

… and other challenges
• 17 GB test database
• 46 projects
• 300k lines of code
• >2 minutes build time

What can I do with this?

The first change request

Change request
Source: http://irodahaz.info
We need to replace
that window up
there!

0. Get the infrastructure ready
Source: http://hfsaustralia.com.au/storage.html

0. Get the infrastructure ready
We need a healthy local dev and CI environment!
• Make a dummy test and get it running!
• Setup the desired testing model
(e.g. SpecFlow)
• Automated the scenario to exercise
the app with it’s dependencies (e.g.
database)
• Ignore/skip/delete unstable tests

1. Capture current behavior
• Based on the way it was explained by the client
• We did not worry about automation
• We did worry about details

1. Capture current behavior
Red

2. Automate “Then” steps
• Feel free to hard-wire concrete data (IDs)!
Red

3. Automate “When”
with hard-wired data
• We have something to start with!
• (But its obviously nasty with “2347599”)
Green

It’s passing, although
we haven’t done
anything for the
“Given”…

We’ve got a scaffolding!
Source: Wikipedia

We need to get rid of the hard-wired data!

4. Pick off a bite!
1
2
3
4
5
8
9
#6
7
Aut
#
#’

4. Pick off a bite
Refactor

We have a test now
for the current
behavior…
Let’s implement the
feature!

We have scaffolded our application for
implementing this feature!

5. Describe an example of the new feature
Red

6. Automate and implement it!
• You can even forget that your are maintaining a legacy app here…
Green

GreenRed
Refactor
We not only made it, but…
• We established a CI/CD
pipeline
• We cleared out a
misunderstanding before
implementing the change
• We created a few reusable
automation steps

BDD for implementing a change request
• We addressed the system through a new feature
• Ensured that the test infrastructure works
• Scaffolded the app with a test for the current behavior using hard wired data
• Refactored the automation to eliminate some parts of these data – taken apart a
bit of the scaffolding
• Described and implemented the new feature
• Used the automation infrastructure for adding further tests

Let’s fix a bug!

The first bug

GreenRed
Refactor
We not only made it, but…
• We isolated the issue
• We solved a testing challenge that was
even a problem for manual testing
• We covered another area of the
application with tests
• We created again a few more reusable
automation steps

Shall we keep
this scenario?

Shall we keep this scenario?
• Special context
• The app gets to an inconsistent
state (workflow stopped, script
running)
• The bug was in the SSH library

Pic: http://gasparnagy.com/2017/02/balancing-scenarios-and-unit-tests-case-study-with-specflow/
Timeout
Scenario

A classification of quality aspects
Functional
• Works as
expected
• Expectations
are good
• Expectations
are
documented
Usability
• Secure
• Fast
• Convenient
• Pretty
• Consistent
• Predictable
Strategic
• Architecture
• Code quality
• Easy to
integrate
• Flexible

Pic: http://gasparnagy.com/2017/02/balancing-scenarios-and-unit-tests-case-study-with-specflow/
Timeout
Scenario
Srv-UI Functional
Usability
Strategic
Edge
case
Argument
check
Timeout
Test
Happy
Path
Func1
Func2

Functional
Usability
Strategic
Forrás: http://gasparnagy.com/2017/02/balancing-scenarios-and-unit-tests-case-study-with-specflow/
Happy
path
Srv-UI
Edge
case
Argument
check
Ext call
timeout
Func1
Func2

Srv-UI
Functional
Usability
Strategic
Edge
case
Argument
check
Ext call
timeout
Forrás: http://gasparnagy.com/2017/02/balancing-scenarios-and-unit-tests-case-study-with-specflow/
Happy
Path
Func1
Func2

Shall we keep regression tests?
• It depends…
• If the bug highlighted an important business case – keep it!
• If it described a special situation – delete it!
• And cover the root cause with technical tests
• Maintaining regression scenarios is costly!

Working on a legacy app does not mean that you
cannot apply BDD process.
The scenarios can guide you to discover more and
more from the application!
As you learn more, the scaffolding can be removed…

Happy maintenance!

Gáspár Nagy
coach • trainer • bdd addict • creator of specflow
@gasparnagy • gaspar@specsolutions.eu
Thank you!
http://bddbooks.com

Scaffolding a legacy app with BDD scenario (Agile in the City Bristol 2017)

More Related Content

What's hot (20)

Similar to Scaffolding a legacy app with BDD scenario (Agile in the City Bristol 2017) (20)

More from Gáspár Nagy (14)

Recently uploaded (20)

Scaffolding a legacy app with BDD scenario (Agile in the City Bristol 2017)