The BDD term was coined first by Dan North – back in 2006. BDD encourages writing tests in a natural, human-readable language that focuses on the behavior of the application. It defines a clearly structured way of writing tests following three sections (Arrange, Act, Assert): -given some preconditions (Arrange) -when an action occurs (Act) -then verify the output (Assert) The Mockito library is shipped with a BDDMockito class which introduces BDD-friendly APIs. This API allows us to take a more BDD friendly approach arranging our tests using given() and making assertions using then().

1. BDDMockito
@rorypreddy

6. BDD
Given- Set of
preconditions
Then-Some
testable outcome
When-When a
event occurs
Uses Given-Then-When (Gherkin)

7. So BDD is…
• An evolution of Test Driven
Development
• Created by Dan North in 2003:
“Programmers wanted to know where to
start, what to test and what not to test,
how much to test in one go, what to call
their tests, and how to understand why a
test fails.”

8. BDDMockito
• The Mockito library is shipped with a
BDDMockito class
• Provides BDD aliases for
various Mockito methods:
– write our Arrange step using given (instead
of when)
– write our Assert step using then (instead of verify)

9. Write a Story
Given list of Trading Users
When I retrieve Users starting with “R”
Then the list should have 2 items in it
…

10. Setup Objects
import static org.mockito.BDDMockito.given;
import static org.mockito.Mockito.when;
…
List<String> tradingUsers;
TradingUserRepository tradingUserRepository;
TradingService tradingService;
@Before
public void init() {
tradingUsers = Arrays.asList("Rory","Robert", "Max");
tradingUserRepository = mock(TradingUserRepository.class);
tradingService = new TradingService(tradingUserRepository);
}

11. Old Style Mockito
//given
when(tradingUserRepository.retrieveUsers("TradingUsers"))
.thenReturn(tradingUsers);
//when
List<String> users = tradingService
.retrieveUsersStartingWithR("TradingUsers");
//then
verify(tradingUserRepository)
.retrieveUsers("TradingUsers");
assertEquals(2, users.size());

12. BDD Mockito
//given
given(tradingUserRepository
.retrieveUsers("TradingUsers"))
.willReturn(tradingUsers);
//when
List<String> users = tradingService
.retrieveUsersStartingWithR("TradingUsers");
//then
then(tradingUserRepository)
.should()
.retrieveUsers("TradingUsers");
assertThat(users.size(), is(2));

14. https://bclozel.github.io/webflux-workshop/

15. Questions
@rorypreddy
• https://github.com/roryp/bddmockito
• https://github.com/bclozel/webflux-workshop.git