Selenium Camp, 25.02.2017

1. Excuse me, sir,
do you have a
moment to talk
about tests in
Kotlin?
—
Leonid Rudenko

2. Why?
—
_2

3. Why?
—
_3

4. Why?
—
Selenium Camp 2016
#4 Make Your Automation ier
_4

5. What’s going on here
—
• What is Kotlin?
• Problems Kotlin solves
• Demo
Excuse me, sir, do you have a moment to talk about tests in Kotlin? _5

6. What’s going on here
—
• What is Kotlin?
• Problems Kotlin solves
• Demo
Excuse me, sir, do you have a moment to talk about tests in Kotlin? _6

7. Kotlin is...
—
• JVM language from JetBrains – Java 6+
1. What is Kotlin? _7

8. Kotlin is...
—
• JVM language
• Statically typed
1. What is Kotlin? _8

9. Kotlin is...
—
• JVM language
• Statically typed
• Multi-paradigm – OOP & functional
1. What is Kotlin? _9

10. Kotlin is...
—
• JVM language
• Statically typed
• Multi-paradigm
• Pragmatic
1. What is Kotlin? _10

11. Kotlin is...
—
• JVM language
• Statically typed
• Multi-paradigm
• Pragmatic
• Democratic
1. What is Kotlin? _11

12. Kotlin is...
—
• JVM language
• Statically typed
• Multi-paradigm
• Pragmatic
• Democratic
• Safe
1. What is Kotlin? _12

13. Kotlin is...
—
• JVM language
• Statically typed
• Multi-paradigm
• Pragmatic
• Democratic
• Safe
• Concise
1. What is Kotlin? _13
Brevity is the sister of talent.
- Anton Chekhov -

14. Kotlin is...
—
• JVM language
• Statically typed
• Multi-paradigm
• Pragmatic
• Democratic
• Safe
• Concise
• Interoperable
1. What is Kotlin? _14

15. Kotlin is...
—
• JVM language
• Statically typed
• Multi-paradigm
• Pragmatic
• Democratic
• Safe
• Concise
• Interoperable
1. What is Kotlin? _15

16. Kotlin 1.0
—
• 15 Feb 2016 – backward compatibility
1. What is Kotlin? _16

17. Kotlin 1.0
—
• 15 Feb 2016
• kotlinc, Intellij IDEA (plugin), Eclipse (plugin), NetBeans (plugin)
1. What is Kotlin? _17

18. Kotlin 1.0
—
• 15 Feb 2016
• kotlinc, Intellij IDEA (plugin), Eclipse (plugin), NetBeans (plugin)
• Open source https://github.com/jetbrains/kotlin
1. What is Kotlin? _18

19. 1. What is Kotlin? _19

20. _20

21. Google Trends: Kotlin 1y
—
1. What is Kotlin? _21

22. Google Trends: Kotlin vs Groovy 1y
—
1. What is Kotlin? _22

23. Where Kotlin is used
—
• JetBrains products
1. What is Kotlin? _23

24. Where Kotlin is used
—
• JetBrains products
• Android
1. What is Kotlin? _24

25. Where Kotlin is used
—
• JetBrains products
• Android
• Server & Desktop
1. What is Kotlin? _25

26. Where Kotlin is used
—
• JetBrains products
• Android
• Server & Desktop
• Gradle 3.0 https://github.com/gradle/gradle-script-kotlin
1. What is Kotlin? _26

27. Where Kotlin is used
—
• JetBrains products
• Android
• Server & Desktop
• Gradle 3.0
• (Web) Test Automation
1. What is Kotlin? _27

28. Test Automation: why Kotlin?
—
• Syntax similar to Java
1. What is Kotlin? _28

29. Test Automation: why Kotlin?
—
• Syntax similar to Java
• Clean test code
Conciseness
Easy to read == easy to understand
Collective code ownership, effective code review
1. What is Kotlin? _29

30. Test Automation: why Kotlin?
—
• Syntax similar to Java
• Clean test code
Conciseness
Easy to read == easy to understand
Collective code ownership, effective code review
• Safe test code
1. What is Kotlin? _30

31. What’s going on here
—
• What is Kotlin?
• Problems Kotlin solves
• Demo
Excuse me, sir, do you have a moment to talk about tests in Kotlin? _31

32. Kotlin features
—
• Extension functions
• Data classes
• Lambda functions
• Smart cast
• Type inference
• Null safety
2. Problems Kotlin solves _32

33. 1. Problem: Maps and Lists in Java
—
// Java
Map<Integer, Credentials> users = new HashMap<>();
users.put(1, new Credentials("vasya", "123456"));
users.put(2, new Credentials("johny", "qwerty"));
users.put(3, new Credentials("admin", "admin"));
List<Integer> responseCodes = new ArrayList<>();
responseCodes.add(200);
responseCodes.add(302);
2. Problems Kotlin solves _33

34. 1. Solution: Kotlin collections
—
// Kotlin
val users = mapOf(
1 to Credentials("vasya", "123456"),
2 to Credentials("johny", "qwerty"),
3 to Credentials("admin", "admin"))
val responseCodes = listOf(200, 302)
2. Problems Kotlin solves _34

35. 1. Collections: Map
—
// Kotlin
val users = mapOf(
1 to Credentials("vasya", "123456"),
2 to Credentials("johny", "qwerty"),
3 to Credentials("admin", "admin"))
Map<Integer, Credentials>
new
users.put(4, Credentials("...", "..."))
2. Problems Kotlin solves _35

36. 1. Collections: Traversing a map
—
// Java
for (Map.Entry<Integer, Credentials> pair : users.entrySet()) {
System.out.println(pair.getKey() + "->" + pair.getValue());
}
// Kotlin
for ((id, creds) in users) {
println("$id->$creds")
}
2. Problems Kotlin solves _36

37. 1. Collections: forEach, filters, sorting...
—
// Kotlin
val link = driver.findElements("a").firstOrNull {
it.text == "Selenium Camp"
}
2. Problems Kotlin solves _37

38. 1. Collections: Java & Groovy
—
• Java 7
• Java 8 (Stream API)
• Groovy
2. Problems Kotlin solves _38

39. 1. Collections: forEach, filters, sorting...
—
2. Problems Kotlin solves _39
// Kotlin
val link = driver.findElements("a").firstOrNull {
it.text == "Selenium Camp"
}

40. 2. Problem: framework can’t do what you need it to do
—
// Java
public static List<WebElement> findElements(WebDriver driver,
String selector) {
return driver.findElements(By.cssSelector(selector));
}
findElements(driver, "a");
2. Problems Kotlin solves _40

41. 2. Problem: framework can’t do what you need it to do
—
2. Problems Kotlin solves _41

42. 2. Solution: Extension functions
—
// Kotlin
fun WebDriver.findElements(selector: String): List<WebElement>{
return this.findElements(By.cssSelector(selector))
}
driver.findElements("a")
2. Problems Kotlin solves _42

43. 2. Extension functions
—
// Kotlin
fun WebDriver.findElements(selector: String): List<WebElement>{
return this.findElements(By.cssSelector(selector))
}
driver.findElements("a")
2. Problems Kotlin solves _43

44. 2. Extension functions
—
// Kotlin
fun WebDriver.findElements(selector: String): List<WebElement>{
return this.findElements(By.cssSelector(selector))
}
driver.findElements("a")
2. Problems Kotlin solves _44

45. 2. Extension functions
—
// Kotlin
fun WebDriver.findElements(selector: String): List<WebElement>{
return this.findElements(By.cssSelector(selector))
}
driver.findElements("a")
2. Problems Kotlin solves _45

46. 2. Extension functions: Java & Groovy
—
• Java
• Groovy (Extension Modules)
2. Problems Kotlin solves _46

47. 3. Problem: small classes are not small
—
// Java
public class Credentials {
private final String username;
private final String password;
}
2. Problems Kotlin solves _47

48. 3. Problem: small classes are not small
—
// Java
public class Credentials {
private final String username;
private final String password;
public Credentials(String username, String password) {
this.username = username;
this.password = password;
}
}
2. Problems Kotlin solves _48

49. 3. Problem: small classes are not small
—
// Java
public class Credentials {
private final String username;
private final String password;
public Credentials(String username, String password) {
this.username = username;
this.password = password;
}
public String getUsername() { return username; }
public String getPassword() { return password; }
}
2. Problems Kotlin solves _49

50. 3. Problem: small classes are not small
—// Java
public class Credentials {
private final String username;
private final String password;
public Credentials(String username, String password) {
this.username = username;
this.password = password;
}
public String getUsername() { return username; }
public String getPassword() { return password; }
@Override
public String toString() {
return username + '/' + password;
}
}
2. Problems Kotlin solves _50

51. 3. Problem: small classes are not small
—// Java
public class Credentials {
private final String username;
private final String password;
public Credentials(String username, String password) {
this.username = username;
this.password = password;
}
public String getUsername() { return username; }
public String getPassword() { return password; }
@Override
public String toString() {
return username + '/' + password;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Credentials that = (Credentials) o;
if (username != null ? !username.equals(that.username) : that.username != null) return false;
return password != null ? password.equals(that.password) : that.password == null;
}
@Override
public int hashCode() {
int result = username != null ? username.hashCode() : 0;
return 31 * result + (password != null ? password.hashCode() : 0);
}
}
2. Problems Kotlin solves _51

52. 3. Problem: 27 lines
—// Java
public class Credentials {
private final String username;
private final String password;
public Credentials(String username, String password) {
this.username = username;
this.password = password;
}
public String getUsername() { return username; }
public String getPassword() { return password; }
@Override
public String toString() {
return username + '/' + password;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Credentials that = (Credentials) o;
if (username != null ? !username.equals(that.username) : that.username != null) return false;
return password != null ? password.equals(that.password) : that.password == null;
}
@Override
public int hashCode() {
int result = username != null ? username.hashCode() : 0;
return 31 * result + (password != null ? password.hashCode() : 0);
}
}
2. Problems Kotlin solves _52

53. 3. Solution: direct to Kotlin – 18 lines
—// Java
public class Credentials {
private final String username;
private final String password;
public Credentials(String username, String password) {
this.username = username;
this.password = password;
}
public String getUsername() { return username; }
public String getPassword() { return password; }
@Override
public String toString() {
return username + '/' + password;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Credentials that = (Credentials) o;
if (username != null ? !username.equals(that.username) : that.username != null)
return false;
return password != null ? password.equals(that.password) : that.password == null;
}
@Override
public int hashCode() {
int result = username != null ? username.hashCode() : 0;
return 31 * result + (password != null ? password.hashCode() : 0);
}
}
2. Problems Kotlin solves _53
// Kotlin
class Credentials {
private val username: String
private val password: String
constructor(username: String, password: String) {
this.username = username
this.password = password
}
fun getUsername(): String { return username }
fun getPassword(): String { return password }
override fun toString() = username + '/' + password
override fun equals(other: Any?): Boolean {
if (this === other) return true
if (other?.javaClass != javaClass) return false
other as Credentials
return username == other.username && password == other.password
}
override fun hashCode() = 31 * username.hashCode() + password.hashCode()
}

54. 3. Solution: remove getters – 16 lines
—// Kotlin
class Credentials {
val username: String
val password: String
constructor(username: String, password: String) {
this.username = username
this.password = password
}
//fun getUsername(): String { return username }
//fun getPassword(): String { return password }
override fun toString() = username + '/' + password
override fun equals(other: Any?): Boolean {
if (this === other) return true
if (other?.javaClass != javaClass) return false
other as Credentials
return username == other.username && password == other.password
}
override fun hashCode() = 31 * username.hashCode() + password.hashCode()
}
2. Problems Kotlin solves _54

55. 3. Solution: primary constructor – 10 lines
—// Kotlin
class Credentials(val username: String, val password: String) {
//val username: String
//val password: String
//constructor(username: String, password: String) {
// this.username = username
// this.password = password
//}
override fun toString() = username + '/' + password
override fun equals(other: Any?): Boolean {
if (this === other) return true
if (other?.javaClass != javaClass) return false
other as Credentials
return username == other.username && password == other.password
}
override fun hashCode() = 31 * username.hashCode() + password.hashCode()
}
2. Problems Kotlin solves _55

56. 3. Solution: data class – 1 line
—
// Kotlin
data class Credentials(val username: String, val password: String) {
//override fun toString() = username + '/' + password
//override fun equals(other: Any?): Boolean {
// if (this === other) return true
// if (other?.javaClass != javaClass) return false
// other as Credentials
// return username == other.username && password == other.password
//}
//override fun hashCode() = 31 * username.hashCode() + password.hashCode()
}
2. Problems Kotlin solves _56

57. 3. Solution: Kotlin data classes
—
// Kotlin
data class Credentials(val username: String, val password: String)
val creds = Credentials("a", "b")
println(creds.username) // a
creds.username = "you can't do that"
println(creds) // Credentials(username=a, password=b)
println(creds == Credentials("a", "b")) // true
2. Problems Kotlin solves _57

58. 3. Solution: Kotlin data classes
—
// Kotlin
data class Credentials(val username: String, val password: String) {
override fun toString(): String {
return "$username/$password"
}
}
println(Credentials("one", "two")) // one/two
2. Problems Kotlin solves _58

59. 3. Data classes: Java & Groovy
—
• Java (Lombok https://projectlombok.org/)
• Groovy (@groovy.transform.Canonical)
2. Problems Kotlin solves _59

60. 4. Problem: steps in Allure report
—
// Java
driver.findElement("button").click();
2. Problems Kotlin solves _60

61. 4. Problem: steps in Allure report
—
// Java
@Step("Click the button")
public void clickButton() {
driver.findElement("button").click();
}
clickButton();
2. Problems Kotlin solves _61

62. 4. Solution: steps in Allure report
—
// Java 8
@Step("{0}")
public void step(String title, Runnable code) {
code.run();
}
step("Click the button", () -> {
driver.findElement("button").click();
});
2. Problems Kotlin solves _62

63. 4. Solution: steps in Allure report
—
// Kotlin
@Step("{0}")
fun step(title: String, code: () -> Any) = code()
step("Click the button") {
driver.findElement("button").click()
}
2. Problems Kotlin solves _63

64. 4. Solution: just compare
—
// Java 8
step("Click the button", () -> {
// your code here
});
// Kotlin
step("Click the button") {
// your code here
}
2. Problems Kotlin solves _64

65. 4. Steps in Allure report: Java & Groovy
—
• Java 7
• Java 8
• Groovy
2. Problems Kotlin solves _65

66. 5. Problem: checked exceptions
—
// Java
URLDecoder.decode(param, "UTF-8");
2. Problems Kotlin solves _66

67. // Java
URLDecoder.decode(param, "UTF-8");
// Kotlin
URLDecoder.decode(param, "UTF-8")
5. Solution: no checked exceptions
—
2. Problems Kotlin solves _67

68. 5. Checked exceptions: Java & Groovy
—
• Java
• Groovy
2. Problems Kotlin solves _68

69. 6. Problem: unchecked cast
—
// Java
Object results
= ((JavascriptExecutor) driver).executeScript("...");
2. Problems Kotlin solves _69

70. // Java
Object results
= ((JavascriptExecutor) driver).executeScript("...");
if (results instanceof List) {
List<String> list = ((List<Object>) results)
.stream()
.filter(String.class::isInstance)
.map(String.class::cast)
.collect(toList());
}
6. Problem: unchecked cast
—
2. Problems Kotlin solves _70

71. // Java
Object results
= ((JavascriptExecutor) driver).executeScript("...");
if (results instanceof List) {
List<String> list = ((List<Object>) results)
}
6. Problem: unchecked cast
—
2. Problems Kotlin solves _71

72. // Kotlin
val results
= (driver as JavascriptExecutor).executeScript("...")
if (results is List<*>) {
val list = results.filterIsInstance<String>()
}
6. Solution: Kotlin smart cast
—
2. Problems Kotlin solves _72

73. // Kotlin
val results
= (driver as JavascriptExecutor).executeScript("...")
if (results is List<*>) {
val list = results.filterIsInstance<String>()
}
6. Solution: Kotlin smart cast
—
2. Problems Kotlin solves _73

74. 6. Unchecked cast: Java & Groovy
—
• Java
• Groovy
2. Problems Kotlin solves _74

75. 7. Problem: Java is verbose
—
2. Problems Kotlin solves _75

76. 7. Solution: Kotlin syntactic sugar
—
// Java
actualText.equals(expectedText)
// Kotlin
actualText == expectedText
2. Problems Kotlin solves _76

77. 7. Solution: String templates
—
// Java
String s = "date: " + date + " and author: " + USER.getName();
String s =
format("date: %s and author: %s", date, USER.getName());
// Kotlin
val s = "date: $date and author: ${USER.name}"
2. Problems Kotlin solves _77

78. 7. Solution: ranges
—
// Java
for (int i = 0; i <= 10; i += 2)
// Kotlin
for (i in 0..10 step 2)
2. Problems Kotlin solves _78

79. 7. Solution: Kotlin rich standard library
—
// Java
!list.isEmpty()
// Kotlin
list.isNotEmpty()
2. Problems Kotlin solves _79

80. 7. Solution: Kotlin type inference
—
// Java
final int i = 0;
final String s = "abc";
final List<String> list = new ArrayList<>();
// Kotlin
val i = 0
val s = "abc"
val list = listOf("a", "b", "c")
2. Problems Kotlin solves _80

81. 7. Verbosity: Java & Groovy
—
• Java
• Groovy
2. Problems Kotlin solves _81

82. 8. Problem: java.lang.NullPointerException
—
2. Problems Kotlin solves _82

83. 8. Solution: Null safety
—
var username: String
username = null // compilation error
2. Problems Kotlin solves _83

84. 8. Null safety
—
var username: String
username = null // compilation error
var username: String?
username = null // ok
2. Problems Kotlin solves _84

85. 8. Null safety
—
var username: String // non-nullable String
username = null
var username: String? // nullable String
username = null
2. Problems Kotlin solves _85

86. 8. Null safety: safe call
—
var username: String? = "Vasya"
var count = username.length // compilation error
2. Problems Kotlin solves _86

87. 8. Null safety: safe call
—
var username: String? = "Vasya"
var count = username?.length // ok, count is 5
username = null
var count = username?.length // ok, count is null
2. Problems Kotlin solves _87

88. 8. Null safety: Elvis operator
—
input.sendKeys(username ?: "Guest")
var images = findAllImagesOnPage()
?: throw AssertionError("No images")
2. Problems Kotlin solves _88
?:

89. 8. Null safety: Java & Groovy
—
• Null safety: Java (Optional<T> in Java8), Groovy
• Safe call: Java, Groovy
• Elvis operator: Java, Groovy
2. Problems Kotlin solves _89

90. Java vs Groovy vs Kotlin
—
2. Problems Kotlin solves _90
1 2 3 4 5 6 7 8
Java 7 – – – – – – – –
Java 8 ± – – + – – – –
Groovy + ± + + + – + –
Kotlin + + + + + + + +

91. Why not Groovy?
—
• Not statically typed: runtime bugs
• Not statically typed: performance
• Not statically typed: IDE support
• No null safety
2. Problems Kotlin solves _91

92. What’s going on here
—
• What is Kotlin?
• Problems Kotlin solves
• Demo
Excuse me, sir, do you have a moment to talk about tests in Kotlin? _92

93. Example test project in Kotlin
—
• JUnit http://junit.org/junit4/
• Html Elements https://github.com/yandex-qatools/htmlelements
• Allure Framework https://github.com/allure-framework/
• Gradle https://gradle.org/
• gradle-docker-plugin https://github.com/bmuschko/gradle-docker-plugin
3. Demo _93

94. https://github.com/leonsabr/seleniumcamp-kotlin-demo
—
3. Demo _94
• Kotlin + { Gradle, JUnit, Selenium, Html Elements, Allure } = OK

95. https://github.com/leonsabr/seleniumcamp-kotlin-demo
—
3. Demo _95
• Kotlin + { Gradle, JUnit, Selenium, Html Elements, Allure }
• Java interoperability

96. https://github.com/leonsabr/seleniumcamp-kotlin-demo
—
3. Demo _96
java kotlin ∆
main 670 434 35,2%
test 92 84 8,7%
total 762 518 32%
• Kotlin + { Gradle, JUnit, Selenium, Html Elements, Allure }
• Java interoperability
• Conciseness (lines of code)

97. Useful links
—
• Reference http://kotlinlang.org/docs/reference/
• List of Kotlin resources https://kotlin.link/
• Try Kotlin online http://try.kotl.in/
• Slack https://kotlinlang.slack.com/
_97

98. Thank you
for your attention
—
jetbrains.com
leonid.rudenko@jetbrains.com
@leonsabr