BEHAVIOR DRIVEN DEVELOPMENT Ritesh Mehrotra. TechTalks, 2018

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1 BEHAVIOR DRIVEN DEVELOPMENT Ritesh Mehrotra

2 References BDD in action by John Ferguson Smart Specification by example by Gojko Adzic

3 Agenda What is BDD? How it differs from complements TDD? Real examples on TDD/BDD Dive deeper into BDD Q & A

4 The beginning Approach to collaboratively develop software that delivers value and is transparent Coined and developed by Dan north Meant to address limitations with TDD Popular frameworks: Cucumber, Specflow, Jasmine(BDD like), Jbehave Expressed in Gherkin language

5 Gherkin language Feature: Knowledge sharing session Narrative: As a speaker, I want to record my talk, so that I can replay it later for audience who could not attend Scenario: Recording a session Given: I am a speaker in a session And: I have placed a camera in the room When: I start the recording Then: The session should get recorded

6 What is TDD? Set of techniques that encourages simple design and test suites that inspire confidence Kent Beck Write a failing automated test before code Remove duplication A failing test without code Write code to pass the test Refactor code without letting the test fail

7 Why TDD? Improves the software design Enhances developer ability to write readable and easier-to-maintain code Helps set the boundaries of expected work - example Subsequently lesser defects

8 So where is the problem?

9 Persona #1 Name: Max Age: 35 Occupation: Software Professional BIO Software developer and consultant. Has a family of 4 He has just moved to Singapore on employment visa with a multi-national company. On induction, his employer, familiarized Max with the surroundings, work culture and terms of employment contract. Max is staying in a company sponsored hotel, and will need to rent a place within a week s time. He didn t anticipate the expenses, and is carrying little cash. He hopes he will be able to cover expenses with first salary due soon The company pays all their employees at last day of the month through bank transfers. He has joined in 3 rd week of month, and needs a account soon to receive his salary in time.

10 Persona #2 Name: Rob Age 50 Occupation: Trader and Investor Bio Rob is an Trader and investor with business interest in Asia-pacific region. Primarily based in Singapore, he travels across China, Indonesia, Cambodia and India very frequently for business. He often employs vendors for his business and pays them through cheque post work. Due to his busy schedule and frequent travels, the payments are sometimes late and annoys the business partners. To secure his and partners business interests, he needs a easier way of making payments

11 Features What? In order to make payments to contractors, As a bank customer, I want to initialize a funds transfer from my savings account Why? Who? In order to receive payments for my work, As a prospective banking customer, I want to open a savings bank account

12 Story #1 Title: Open a savings account In order to receive payments for my work, As a prospective banking customer, I want to open a savings account

13 Acceptance criteria Inputs: - Full name - Unique identifier (NRIC, FIN, Passport) - Address - address - Phone number - Agreement on T&C - Account Type: Savings Output: - Account number: 6 digit unique account number - Account type: Savings - Deposit funds - Withdraw funds - Statements - Debit card

14 Story #2 Title: Transfer funds from one account to another In order to make payment to contractor, As a bank customer, I want to initialize a funds transfer from my savings account

15 Acceptance criteria Inputs: - From account: 6 digit account number - To account: 6 digit account number - Amount: Decimal value greater than ZERO(0). Referred hereafter as $ Output: - Transaction id: Numeric id - From account debited of $(decimal value) - To account credited of $(decimal value)

16 Let s code

17 The limitation with TDD What all to test? How much to test? What should we name it? How to validate that tests cover the acceptance criteria? Maintenance and readability a challenge as product grows in size Does it the right way. But does it do the right thing?

18 BDD deep dive

19 What is BDD again? BDD = TDD + Enhanced business collaboration Aligned to the business value A single source of truth equally understood by business and development teams

20 Whose behavior? Business Consumer Customers/Beneficiaries Staff Govt. Agencies/Regulatory/Audit

21 What is value? Increase profit - Eg. New features Protect profit Eg. Customer satisfaction Reduce cost Eg. Support Avoid future cost Eg. Regulatory

22 Where is value?

23 IDENTIFY THE VALUE

24 (Why?) * 5

25 RCA example The system is currently down Why? The underlying authentication service is failing so we cannot log in Why? The authentication service cannot connect to repository Why? The connection parameters are incorrect Why? There was a change in database host name which was not updated in authentication service

26 Applied to goal discovery We want to offer $ 25 cashback for customers who do less than 10 withdrawals a month? Why do you offer that? A promotion will encourage more customers to do lesser withdrawals Why do you want to encourage them? By means of that, we want to promote cashless transactions Why so? Because we want to reduce usage of ATM Why? Maintaining the ATMs is an additional cost, and our analysis suggests that we will be able to save cost by 5% by reducing usage

27 Impact mapping Why? Who? How? What? Enable cashless transactions Pay online Pay by card Save the cost by 5% Pay by cheque Offer cashback on less than 10 withdrawals Capture number of transactions Business Goal Stakeholders Capabilities Features

28 Approach

29 Seek example Can you give me an example? Precise specifications so delivery teams avoid rework caused by ambiguity Objective way to measure when work is complete Documentation to facilitate change, both in terms of features and team structure Described in book Specification by Example by Gojko Adzie

30 Let s revisit code

31 BDD in a nutshell

32 Thank You!!