l'abc du bdd (behavior driven development)
DESCRIPTION
Une introduction au Behavior Driven Development, avec plein d'idées pour tout de suite! et applicable à tout projet. Il sera question: * de passer de l'incompréhension à savoir qu'on ne sait pas * des westerns spaghetti aux Three Amigos, * de reléguer le Comment au second plan pour laisser sa place au Pourquoi! * de rendre des spécifications exécutables * de découvrir qu'un concombre n'est pas qu'un Cucurbitacée aux feuilles tri-lobées * d'automatisation comme outil de non-regression Au cours de cette session, nous expliquerons ce qu'est le BDD. Nous verrons qu'il n'est pas question d'outils ou de tests, mais de collaboration et de discussion entre les différentes parties prenantes: du métier aux développeurs en passant par les testeurs. Cette presentation s'adresse à l'ensemble de ces populations en expliquant l'importance qu'il y a à se comprendre, et qu'il n'est pas nécessaire d'avoir des outils sophistiqués pour avoir des bénéfices immédiats. Nous verrons quelques pratiques de discussion qui permettent d'arriver à une meilleure compréhension et à une description du besoin. Nous verrons aussi comment des exemples concrets permettent de s'assurer d'une compréhension commune et comment ils permettent de construire un langage unique et non ambigu. Nous verrons comment rendre ces spécifications executables en réutilisant les exemples construits précédemment et en les automatisant. Ceux-ci viendront renforcer les tests d'acceptance et devenir des tests de non regressions. Enfin, nous verrons que cette démarche nous permettra d'avoir une documentation vivante et toujours à jour de notre système. Idées pour tout de suite Communication, Clarification par des Exemples concrets, Spécifications exécutablesTRANSCRIPT
BA CL’BDDCE QUE C’est
OU Ce QUE C’est pas…
Arnauld Loyer @aloyer
2014
du
http://pencilink.blogspot.fr/2010/10/iron-man-160-jim-starlin-cover-steve.html
It’s NOT about tools
It’s about Communication and Behavior!
@aloyer
http://ungoliantschilde.tumblr.com/post/78793890826/ungoliantschilde-barry-windsor-smith-that
It’s NOT about Testing
It’s about Exploring the Unknown
@aloyer
It’s not about Silo!Or Acceptance
Criteria
It’s about Sharing
and Understanding
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It’s about Driven Development!
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Qu'est ce qui se passe?
Modèle Mental
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Qu'est ce qui se passe?
Modèle Mental
Ce qui est expliqué
Ce qui n'est pas
retranscrit Modèle Mental
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Qu'est ce qui se passe?
Modèle Mental
Ce qui est expliqué
Ce qui n'est pas
retranscrit Modèle Mental
Ce que l'autre comprend
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Qu'est ce qui se passe?
Ce qui est spécifié
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Qu'est ce qui se passe?
Ce qui va être testé
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Qu'est ce qui se passe?
Ce qui va être testé
Ce qui est réalisé@
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Qu'est ce qui se passe?
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Qu'est ce qui se passe?
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Qu'est ce qui se passe?
Correspond à l'idée initiale
Ce qui a été réalisé
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Qu'est ce qui se passe?
Correspond à l'idée initiale
Ce qui a été réaliséNNNAaannnnnn
vs
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"is this a bug or is this not a bug”
a bug?
a feature?
an enhancement?
a beature?
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3 steps 3 model
3 interpretations
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3 visions 1 model 1 goal
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Three Amigos @aloyer
http://paintings-art-picture.com/paintings/archives/85/marvel-comics-retro-captain-america-comic-panel-fighting-phase-1-so-far-so-good-aged
BDD is writing software that matters
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BDD is about conversation
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Why?
Goal?Business Value?
Intention What?
How!
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Why?
Goal?Business Value?
In order to <achieve the vision>
Feature: ...
As a <stakeholder>I want <value>
Intention
As a <role>I want <goal>So that <value>
User focused
What?
How!
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@aloyer
No Narrative No Business Value
Unnecessary Feature !
@aloyer
22
http://devjam.com/2010/08/05/dudes-law-gordon-pask-shoveler/
In order to...Feature: ...
As a...I want to...Scenario: ...Given <a context>When <an event happens>Then <an outcome should occur>
BDD uses examples to illustrate behavior@aloyer
@aloyer
Why do YOU like should?
It encourages debate, and
constant Questioning
of the premise of the application you are
developing.
Dan North, March 2005
@aloyer
Feature: Account Holder withdraws cash from an ATM ! In the following scenario, ATM will stands for Automatic Teller Machine in other word a “Cash machine”. ! In order to get money at any time, even when the bank is closed As an Account Holder I want to withdraw cash from an ATM !Scenario: Account has sufficient funds Given the account balance is 100€ When the Account Holder requests 20€ Then the ATM should dispense 20€ And the account balance should be 80€ And the card should be returned
@aloyer
Scenario: Account has insufficient funds Given the account balance is 10€ And the card is valid And the machine contains enough money When the Account Holder requests 30€ Then the ATM should not dispense any money And the ATM should say there are insufficient funds And the account balance should still be 10€ And the card should be returned
@aloyer
Scenario: Account has insufficient funds Given the account balance is 10€ And the card is valid And the machine contains enough money When the Account Holder requests 30€ Then the ATM should not dispense any money And the ATM should say there are insufficient funds And the account balance should still be 10€ And the card should be returned
FOCUS On the BEHAVIOR DESCRIBED!
@aloyer
@aloyer
Feature: Interpolate !
In order to interpolate values As an Trader I want to interpolate values in a range of Market
data
Why this feature ?
@aloyer
Feature: Linear Interpolation In order to fill the gaps and provide a value for any
maturity As a trader responsible for market-making I want to interpolate linearly values within a range of
points And I want a flat extrapolation outside of the range
of points
Why this feature ?
@aloyer
Scenario: Change the negotiation price from positive to negative => soulte cashflow appears and premium cashflow is modified
!Given an FUNKY_EXOTIC And deal way is sell And deal nature is TOMATO And trade value date is 2012/07/01 And nominal is 100 JPY And negotiation price is 0.20 JPY When I validate the deal Then there are 1 Price cashflows And there are 0 fee cashflows When I change the negotiation price to -0.3 JPY And I validate the deal Then there are 1 Price cashflows And there are 1 fee cashflows And the trade cashflow's payment date is 2012/07/01 And the trade cashflow's way is receive And the trade cashflow's amount is 30 JPY And the fee cashflow's payment date is 2012/07/01 And the fee cashflow's way is give And the fee cashflow's amount is 60 JPY
What about this scenario
@aloyer
What about this scenario
d = new Deal(); d.SetWay(Sell); d.SetNature(Tomato); d.SetValueDate(new Date(...)); d.SetNominal(100, JPY); d.SetNegotiationPrice(0.20, JPY); cf = d.GetCashFlows(); AssertThat(IsEqual(...); ...
Scenario: Change the negotiation price from positive to negative => soulte cashflow appears and premium cashflow is modified
!Given an FUNKY_EXOTIC And deal way is sell And deal nature is TOMATO And trade value date is 2012/07/01 And nominal is 100 JPY And negotiation price is 0.20 JPY When I validate the deal Then there are 1 Price cashflows And there are 0 fee cashflows When I change the negotiation price to -0.3 JPY And I validate the deal Then there are 1 Price cashflows And there are 1 fee cashflows And the trade cashflow's payment date is 2012/07/01 And the trade cashflow's way is receive And the trade cashflow's amount is 30 JPY And the fee cashflow's payment date is 2012/07/01 And the fee cashflow's way is give And the fee cashflow's amount is 60 JPY
@aloyer
SCEnARIO: Fee and Price cashflows when the negotiation price is set to a negative value
!Given a sell for a nominal 100 JPY on FUNKY_EXOTIC TOMATO
negotiation price 0.20 JPY traded on 2012/07/01 When the middle officer validates the deal Then the trade has one Price cashflow and no Fee cashflow When the middle officer changes the negotiation price to -0.3 JPY And the middle officer validates the deal Then the trade has the following cashflows:
What about this scenario
Communicate With the Business People !!!
FlowType
Price Fee
Way
Receive Give
Amount
30 60
Currency
JPY JPY
Payment Date
2012/07/01 2012/07/01
Remarks
100*abs(-0.3) 100*2*abs(-0.3)
@aloyer
Low Tech
Scenario
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Domain Driven Design - Eric Evans @aloyer
In order to...Feature: ...
As a...I want to...
Scenario: ...Given <a context>When <an event happens>Then <an outcome should occur>
Examples help discover things early@aloyer
@aloyer
In order to...Feature: ...
As a...I want to...
Scenario: ...Given <a context>When <an event happens>Then <an outcome should occur>
One may discover that one doesn't know
but others do!
@aloyer
@aloyer
WHAT About Automation !?!
The Green
Thing
?
@aloyer
GLUE
COD
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BDD
FRAM
EWOR
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SCEN
ARIO
APPL
ICAT
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"End to End"
UI FEST, Selenium, Fluentlenium,
HtmlUnit, Watir...
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GLUE
COD
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BDD
FRAM
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SCEN
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APPL
ICAT
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"End to End"
Services
Web, WCF, ...
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GLUE
COD
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BDD
FRAM
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SCEN
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APPL
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Sub-Moduleruntime
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GLUE
COD
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BDD
FRAM
EWOR
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SCEN
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APPL
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"Quasi-Unitaire"runtime
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GLUE
COD
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BDD
FRAM
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SCEN
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APPL
ICAT
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"Quasi-Unitaire"runtime
Mock, Stubs...
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GLUE
COD
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BDD
FRAM
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SCEN
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APPL
ICAT
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Scenario: Account has sufficient funds! Given the account balance is 100€! When the Account Holder requests 20€ Then the ATM should dispense 20€! And the account balance should be 80€! And the card should be returned
SCENARIO
GLUE
COD
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BDD
FRAM
EWOR
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APPL
ICAT
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@aloyer
Scenario: Account has sufficient funds! Given the account balance is 100€! When the Account Holder requests 20€ Then the ATM should dispense 20€! And the account balance should be 80€! And the card should be returned
SCENARIO
GLUE
COD
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BDD
FRAM
EWOR
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APPL
ICAT
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@aloyer
Scenario: Account has sufficient funds! Given the account balance is 100€! When the Account Holder requests 20€ Then the ATM should dispense 20€! And the account balance should be 80€! And the card should be returned
SCENARIO
@Given("^the account balance is (\d+)€$") public void defineAccountBalanceInEuro(BigDecimal balance) { throw new PendingException("Implements me!"); } !@When("^the Account Holder request (\d+)€$") public void withdrawInEuro (BigDecimal amount) { throw new PendingException("Implements me!"); } !@Then("^the ATM should dispense (\d+)€$") public void assertMoneyDispensedInEuro (BigDecimal amount) { throw new PendingException("Implements me!"); } !!!@Then("^the account balance should be (\d+)€$") public void assertBalanceInEuro(BigDecimal amount) { throw new PendingException("Implements me!"); } !
GLUE CODE
APPL
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BDD
FRAM
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@aloyer
Scenario: Account has sufficient funds! Given the account balance is 100€! When the Account Holder requests 20€ Then the ATM should dispense 20€! And the account balance should be 80€! And the card should be returned
SCENARIO
@Given("^the account balance is (\d+)€$") public void defineAccountBalanceInEuro(BigDecimal balance) { account().setBalance(euro(balance)); } !@When("^the Account Holder request (\d+)€$") public void withdrawInEuro (BigDecimal amount) { atm().withdraw(account(), euro(amount)); } !@Then("^the ATM should dispense (\d+)€$") public void assertMoneyDispensedInEuro (BigDecimal amount) { TransactionLog txLog = atm().transactionLog();! Money dispensed = txLog.lastAmountDispensed();! assertThat(dispensed).isEqualTo(euro(amount)); }!!@Then("^the account balance should be (\d+)€$") public void assertBalanceInEuro(BigDecimal amount) { Money actualBalance = account().balance();! assertThat(actualBalance).isEqualTo(euro(amount)); }
GLUE CODE
APPL
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BDD
FRAM
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@aloyer
And that’s all Folks… for the Green Thing!
but remember, you can
automate from unit level to end-to-end
level
@aloyer
THE PointIf only one thing must remain
@aloyer
BDD = Shared understanding by discussing Examples
@aloyer
BDD = Shared understanding by discussing Examples
Three AmiGOS
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BDD = Shared understanding by discussing Examples
Scenario
Three AmiGOS
@aloyer
@aloyer
Questions?
http://rozmaryn.deviantart.com/art/Hellboy-bw-52117973
@aloyer