Playing Tickle Pickle or Writing BDD tests with Spek 2

Hello! I am Dmytro Zaitsev I am here because I love to give presentations. Also, sometimes I develop mobile apps for money. You can find me at @DmitriyZaitsev 2

Agenda ✗ What is Gherkin ✗ Why Gherkin ✗ Gherkin syntax ✗ Examples ✗ Best practices ✗ Pros & Cons 3

Our code evolution Java Kotlin 4

Our tests evolution JUnit Spek Spek2 5

“Tests are specifications” 6

“Test after is not BDD” 7

“Tests do not drive the implementation when they are written afterwards.” 8

“BDD is not about testing. It’s about development” 9

Spek 2 core concepts

Spek 2 Structure

Structure Tests are written using nested lambdas, each scope (level) can either be a group or a test. ✗ Test scope is where you place your assertions/ checks (in JUnit dialect - this is your test method). ✗ Group scope is used to organize your tests. ✗ It can contain test scopes and other group scopes as well. ✗ Group scopes will be eagerly executed during the discovery phase. 12

13 object MySpek: Spek({ group("a group") { test("a test") { ... } group("a nested group") { test("another test") { ... } } } })

Spek 2 Phases

Discovery The goal of this phase is to build the test tree which outlines how the tests are executed. In order to achieve this, Spek will execute all group scopes starting from the root. Phases Execution In this phase the tests are executed. Spek traverses the test tree starting from the root and for each scope it will execute the registered fixtures. 15

16 object MySpek: Spek({ println("1") group("some group") { println("2") test("some test") { println("4") } } group("another group") { println("3") test("another test") { println("5") } } }) Discovery Execution

17 Root Group 1 Group 2 Test 1 Test 2 Test 1 Test 2

Spek 2 Fixtures

19 object MySpek: Spek({ beforeGroup { println("before root") } group("some group") { beforeEachTest { println("before each test") } test("some test") { println("some test") } afterEachTest { println("after each test") } } afterGroup { println("after root”) } })

20 object MySpek: Spek({ beforeGroup { println("before root") } group("some group") { beforeEachTest { println("before each test") } test("some test") { println("some test") } afterEachTest { println("after each test") } } afterGroup { println("after root”) } })

Spek 2 Scope values

22 object MySpek: Spek({ lateinit var cucumber: Cucumber beforeEachTest { cucumber = Cucumber() } })

23 object MySpek: Spek({ val cucumber by memoized { Cucumber() } })

Caching modes You can pass in an optional parameter to memoized which controls how the values are cached. ✗ CachingMode.TEST: each test scope will receive a unique instance, this is the default. ✗ CachingMode.GROUP: each group scope will receive a unique instance. ✗ CachingMode.SCOPE: effectively a singleton. ✗ CachingMode.INHERIT: internal use only. 24

Writing features Gherkin language

✗ Gherkin is a Business Readable, DSL created especially for behavior descriptions. ✗ It gives you the ability to remove logic details from behavior tests. 26

✗ project’s documentation ✗ automated tests. 27 Gherkin serves two purposes

Gherkin syntax

Gherkin syntax Feature: Some terse yet descriptive text of what is desired In order to realize a named business value As an explicit system actor I want to gain some beneficial outcome which furthers the goal Scenario: Some determinable business situation Given some precondition And some other precondition When some action by the actor And some other action And yet another action Then some testable outcome is achieved And something else we can check happens too Scenario: A different situation ... 29

Feature ✗ A feature usually contains a list of scenarios. ✗ You can use group features and scenarios together. ✗ Every scenario consists of a list of steps, which must start with one of the keywords Given, When, Then, or And (or localized one). Spek treats them all the same, but you shouldn’t. 30

Scenario ✗ Scenario is one of the core Gherkin structures. ✗ Every scenario starts with the Scenario: keyword, followed by an optional scenario title. ✗ Each feature can have one or more scenarios ✗ Every scenario consists of one or more steps. 31

Example 32 Feature: Serve coffee In order to earn money Customers should be able to buy coffee at all times Scenario: Buy coffee Given there are 1 coffees left in the machine And I have deposited 1 dollar When I press the coffee button Then I should be served a coffee

33 Spek Feature 1 Feature 2 Given
 When Then Scenario 1 Scenario 2 Scenario 1 Given
 When Then Given
 When Then Given
 When Then Given
 When Then

Steps

Given ✗ The use of Given keyword is to put the system in a familiar state before the user starts interacting with the system. ✗ However, you can omit writing user interactions in Given steps if Given in the "Precondition" step. 35

When ✗ When is the step to define action performed by user 36

Then ✗ The use of 'then' keyword is to see the outcome after the action in when step. ✗ However, you can only verify noticeable changes. 37

And ✗ You may have multiple ‘given’, ‘when’ or ‘then’ 38

Be aware ✗ Given, When, Then, And are test steps. ✗ You can use them interchangeably. ✗ Spek doesn't display any error. However, they will surely not make any 'sense' when read. 39

Scenario outlines Scenario: Eat 5 out of 12 Given there are 12 cucumbers When I eat 5 cucumbers Then I should have 7 cucumbers 40

41 Scenario("Eat 5 out of 12") { lateinit var cucumbers: MutableList Given("There are 12 cucumbers") { cucumbers = MutableList(12) { Cucumber() } } When("I eat 5 cucumbers") { for (i in 0 until 5) cucumbers.removeAt(cucumbers.lastIndex) } Then("I should have 7 cucumbers") { assertEquals(7, cucumbers.size) } }

42 Scenario("Eat 5 out of 20") { lateinit var cucumbers: MutableList Given("There are 20 cucumbers") { cucumbers = MutableList(20) { Cucumber() } } When("I eat 5 cucumbers") { for (i in 0 until 5) cucumbers.removeAt(cucumbers.lastIndex) } Then("I should have 15 cucumbers") { assertEquals(15, cucumbers.size) } }

Scenario outlines Scenario Outline: Eating Given there are cucumbers When I eat cucumbers Then I should have cucumbers Examples: | start | eat | left | | 12 | 5 | 7 | | 20 | 5 | 15 | 43

44 listOf( Example(start = 12, eat = 5), Example(start = 20, eat = 5) ).forEach { o -> Scenario("Eat ${o.eat} out of ${o.start}") { lateinit var cucumbers: MutableList Given("There are ${o.start} cucumbers") { cucumbers = MutableList(o.start) { Cucumber() } } When("I eat ${o.eat} cucumbers") { for (i in 0 until o.eat) cucumbers.removeAt(cucumbers.lastIndex) } Then("I should have ${o.left} cucumbers") { assertEquals(o.left, cucumbers.size) } } }

Best practices

Best practices ✗ Each scenario should execute separately ✗ Every feature should able to be executed along ✗ Steps information should be shown independently ✗ Connect your Scenario's with your requirements ✗ Keep a complete track of what scenarios should be included in a requirement document ✗ Create modular and easy to understand steps ✗ Try to combine all your common scenarios 46

Pros & Cons

Pros ✗ Gherkin is simple enough for non-programmers to understand ✗ Programmers can use it as a very solid base to start their tests ✗ It makes User Stories easier to digest ✗ Gherkin script can easily understand by business executives and developers ✗ Targets the business requirements ✗ A significant proportion of the functional specifications is written as user stories ✗ You don't need to be expert to understand the small Gherkin command set ✗ Gherkin links acceptance tests directly to automated tests ✗ Style of writing tests cases are easier to reuse code in other tests 48

Cons ✗ It requires a high level of business engagement and collaborations ✗ May not work well in all scenarios ✗ Poorly written tests can easily increase test- maintenance cost 49

Demo

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52 Thanks! Any questions? You can find me at: ✗ @DmitriyZaitsev