What makes groovy groovy codeurs en seine - 2013 - light size

What makes
Groovy groovy?
Guillaume Laforge
@glaforge
© 2013 Guillaume Laforge. All rights reserved. Do not distribute without permission.

Guillaume
Laforge
Groovy project lead
at
.
@glaforge
http://glaforge.appspot.com

Simplify the life of
(Java) developers

Great for
scripting

Fit for DomainSpecific Languages

Great for
scripting

Fit for DomainSpecific Languages

Most seamless integration &
interoperability wih java!

Groovy as a
Java superset

It’s so easy
to learn!

class!MathSpec!extends!Specification!{
!!!!def!"maximum!of!two!numbers"()!{
******expect:
!!!!!!!!Math.max(a,!b)!==!c
******where:
!!!!!!!!a!|!b!||!c
!!!!!!!!1!|!3!||!3
!!!!!!!!7!|!4!||!4
!!!!!!!!0!|!0!||!0
!!!!}
}

As safe and fast as Java with
static type checking & compilation

new!MarkupBuilder().html!{
!!!!head!{
!!!!!!!!title!"The!Script!Bowl"
!!!!}
!!!!body!{
!!!!!!!!div(class:!"banner")!{
!!!!!!!!!!!!p!"Groovy!rocks!"
!!!!!!!!}
!!!!}
}

move!forward!at!3.km/h
Expressive,
Concise,
Readable

Speaking of conciseness...
A full Spring app in the span of a tweet!
@RestController
class!App!{
!!!!@RequestMapping("/")
!!!!String!home()!{!"Hello!World!"!}
}

• SmartThings
• Carriots

Services

• European Patent
Ofﬁce
• Amadeus
IoT

Financial

• Crédit Suisse
• JPMorgan
• Fanny Mae
• Mutual of Omaha
• Hypoport
20

• Energy Transfer
• National Cancer Inst.
• IRSN

Internet

• Netﬂix
• LinkedIn
• Google

Technology

Who’s using Groovy?

Most Java code is also
valid Groovy code!

Most Java code is also
valid Groovy code!

Any Java developer is a
Groovy developer!

Flat learning
curve

Easy to learn

Scripts versus Classes
public!class!Main!{
!!!!public!static!void!main(String[]!args)!{
!!!!!!!!System.out.println("Hello");
!!!!}
}

vs
24

Scripts versus Classes
public!class!Main!{
!!!!public!static!void!main(String[]!args)!{
!!!!!!!!System.out.println("Hello");
!!!!}
}

vs
println!"Hello"
24

Semicolons
Parentheses

Optional

Semicolons
Parentheses

Optional
return keyword

Semicolons
Parentheses

Optional
return keyword

public keyword

Semicolons
Parentheses

Optional
Typing!
return keyword

public keyword

Optional...
public!class!Greeter!{
!!!!private!String!owner;
!!!!public!String!getOwner()!{
!!!!!!!!return!owner;
!!!!}
!!!!public!void!setOwner(String!owner)!{
!!!!!!!!this.owner!=!owner;
!!!!}
!!!!public*String!greet(String!name)!{
!!!!!!!!return!"Hello!"!+!name!+!",!I!am!"!+!owner;
!!!!}
}
Greeter!greeter!=!new!Greeter();
greeter.setOwner("Guillaume");
System.out.println(greeter.greet("Marion"));
26

Optional...

Semicolons

!!!!}
!!!!}
!!!!}
}
26

Optional...
!!!!private!String!owner
!!!!!!!!return!owner
!!!!}
!!!!!!!!this.owner!=!owner
!!!!}
!!!!!!!!return!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
Greeter!greeter!=!new!Greeter()
greeter.setOwner("Guillaume")
System.out.println(greeter.greet("Marion"))
27

Optional...
!!!!}
!!!!}
!!!!}
}
28

Optional...
!!!!}
!!!!}
!!!!}
}

Parentheses

28

Optional...
!!!!}
!!!!}
!!!!}
}
greeter.setOwner!"Guillaume"
System.out.println!greeter.greet("Marion")
29

Optional...
!!!!}
!!!!}

return keyword

!!!!}
}
29

Optional...
!!!!!!!!******!owner
!!!!}
!!!!}
!!!!!!!!******!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
30

Optional...
!!!!!!!!******!owner
!!!!}

public keyword

!!!!}
!!!!}
}
30

Optional...
******!class!Greeter!{
!!!!******!String!getOwner()!{
!!!!!!!!******!owner
!!!!}
!!!!******!void!setOwner(String!owner)!{
!!!!}
!!!!*******String!greet(String!name)!{
!!!!}
}
31

Optional...
!!!!!!!!******!owner
!!!!}
!!!!}
!!!!}
}

optional typing

31

Optional...
!!!!!!!!******!owner
!!!!}
!!!!}
!!!!}
}
def!!!!!greeter!=!new!Greeter()
32

Optional...
!!!!!!!!******!owner
!!!!}
!!!!}
!!!!}
}

handy println shortcut

32

Optional...
!!!!!!!!******!owner
!!!!}
!!!!}
!!!!}
}
!!!!!!!!!!!println!greeter.greet("Marion")
33

Optional...

verbose Java properties!

!!!!!!!!******!owner
!!!!}
!!!!}
!!!!}
}
33

Optional...
!!!!*******!String!owner

!!!!}
}
34

Optional...

!!!!}
}

Property notation

34

Optional...

!!!!}
}
greeter.owner!!!!"Guillaume"
35

Optional...

Named argument
constructor
!!!!}
}
greeter.owner!!!!"Guillaume"
35

Optional...

!!!!}
}
def!!!!!greeter!=!new!Greeter(owner:!"Guillaume")
36

Optional...

Interpolated strings!
(aka GStrings)
!!!!}
}
36

Optional...

!!!!!!!!******!"Hello!${name},!I!am!${owner}"
!!!!}
}
37

Optional...

Let’s reformat that
mess of whitespace!

!!!!!!!!******!"Hello!${name},!I!am!${owner}"
!!!!}
}
37

Optional...
class!Greeter!{
***!String!owner
****String!greet(String!name)!{
******!"Hello!${name},!I!am!${owner}"
!!!!}
}
def!greeter!=!new!Greeter(owner:!"Guillaume")
println!greeter.greet("Marion")

38

Optional...
class!Greeter!{
***!String!owner
!!!!}
****String!greet(String!name)!{
******!"Hello!${name},!I!am!${owner}"
!!!!}
!!!!}}
def!greeter!=!new!Greeter(owner:!"Guillaume")
!!!!}println!greeter.greet("Marion")
}
38

Native syntax constructs
• Closures
• Lists
• Maps
• Regular expressions
• Ranges
39

Closures
• Functions as ﬁrst-class citizen of the language

40

Lists
def!list!=!['a',!'b',!'c']
list!<<!'d'
assert!list.contains('d')
assert!list.findAll!{!it.startsWith!'a'!}.size()!==!1
assert!list.collect!{!it.toUpperCase()!}!==!['A',!'B',!'C',!'D']
assert!list.inject('')!{!a,!b!c>!a!+!b!}!==!'abcd'

41

Lists

List definition

def!list!=!['a',!'b',!'c']
list!<<!'d'

41

Lists

List definition

def!list!=!['a',!'b',!'c']

Append an element
(operator overloading)

list!<<!'d'

41

Lists

List definition

def!list!=!['a',!'b',!'c']

Append an element
(operator overloading)

list!<<!'d'

Functional-style
map / filter / reduce
with closures
41

Maps
def!map!=![name:!'Guillaume',!age:!36]
map.daughters!=!['Marion',!'Erine']
assert!map['daughters'].contains('Marion')

42

Maps

Map definition


42

Maps

Map definition


Indexed access

42

Maps

Map definition


Property
notation access

42

Indexed access

Regular expressions
def!pattern!=!~/.*foo.*/
assert!"Alibaba"!==~!/.*(ba){2}/
def!matcher!=!"Superman"!=~!/([AcZ][acz]+)man/
assert!matcher[0][0]!==!'Superman'
assert!matcher[0][1]!==!'Super'
'75001!Paris'.find(/(d{5})s(w)+/)!{!match,!cp,!town!c>
!!!!println!"The!Zip!code!of!${town}!is!${cp}"
}

43

Regular expressions
Pattern
}

43

Regular expressions
Pattern

Match

}

43

Regular expressions
Pattern

Match


Find

}

43

Regular expressions
Pattern

Match


Find

}

Nice way to decompose the matched regions
43

Ranges
def!range!=!'a'..'z'
assert!range.contains('m')
assert!range.contains('z')
def!exclusive!=!1..<10
assert!!exclusive.contains(10)
def!reverse!=!10..0
assert!reverse[0]!==!10
assert!reverse[c1]!==!0
44

Ranges

Range

def!reverse!=!10..0
44

Ranges

Range


Excluded upper bound

def!reverse!=!10..0
44

Ranges

Range



def!reverse!=!10..0
44

Reverse range

Ranges

Range



def!reverse!=!10..0
44

Reverse range
Negative index count
from the end

Strings, GStrings, multiline strings

def!name!=!'Groovy'
def!tmpl!=!"""
!!!!Dear!Mr!${name},
!!!!You're!the!winner!of!the!lottery!
!!!!Yours!sincerly,
!!!!Dave
"""
assert!tmpl.toString().contains('Groovy')

45

Plain java.lang.String
def!name!=!'Groovy'
def!tmpl!=!"""
!!!!Yours!sincerly,
!!!!Dave
"""

45

Plain java.lang.String
def!name!=!'Groovy'
Multiline string with
def!tmpl!=!"""
expression interpolation
!!!!Yours!sincerly,
!!!!Dave
"""

45

Surprising numbers...

System.out.println(!2.0!c!1.1!);

46


System.out.println(!2.0!c!1.1!);
0.8999999999999999

46


System.out.println(!3!/!2!);

47


System.out.println(!3!/!2!);
1

47

BigDecimal by default!

assert!2.0!c!1.1!==!0.9
assert!3!/!2!==!1.5

48


assert!2.0!c!1.1!==!0.9
assert!3!/!2!==!1.5
One of the reasons why microbenchmarks sometimes showed
Groovy to be slow...
48


assert!2.0!c!1.1!==!0.9
assert!3!/!2!==!1.5
One of the reasons why microbenchmarks sometimes showed
Groovy to be slow...
48

But you can use doubles & floats
for performance, with ‘d’ or ‘f ’
suffixes or with explicit type

Powerful
switch / case
on steroids

Powerful
switch / case
on steroids

switch(obj)!{
!!!!case!123:!!!!!!!!!!!!!!!!!!"number!123";!!!!!!!!break
!!!!case!"abc":!!!!!!!!!!!!!!!!"string!abc";!!!!!!!!break
!!!!case!String:!!!!!!!!!!!!!!!"is!a!string";!!!!!!!break
!!!!case![1,!2,!3]:!!!!!!!!!!!!"contained!in!list";!break
!!!!case!~/.*o+.*/:!!!!!!!!!!!!"match!the!regex";!!!break
!!!!case!{!it.isUpperCase()!}:!"closure!criteria";!!break
****default:!"unknown"
}

Named arguments

move!obj,!x:!3,!y:!4

50

Named arguments

Normal argument

50

Named arguments

Normal argument

50

Named argument

Named arguments

Normal argument
Calls:
move(Map m, Object)

50

Named argument

Command chains
• Ability to chain method calls
without parentheses and dots

51

Command chains


51

Command chains

Actually equivalent to:
move(forward).at(3.getKm().div(h))

51

Named arguments and command chains

check!that:!vodka!tastes!good

52

Named arguments and command chains

check!that:!vodka!tastes!good
Will call:
check(that: vodka).tastes(good)

52

Multiple assignment and destructuring
def!(a,!b)!=!['A',!'B']
(a,!b)!=![b,!a]
def!(int!i,!int!j)!=![1,!2]
def!geocode(String!place)!{
!!!!return![45.4,!2.3]
}
def!(la,!lo)!=!geocode("Paris")
assert!la!==!45.4!&&!lo!==!2.3
53

def!(a,!b)!=!['A',!'B']
(a,!b)!=![b,!a]

Classic « swap »

!!!!return![45.4,!2.3]
}
assert!la!==!45.4!&&!lo!==!2.3
53

def!(a,!b)!=!['A',!'B']

With types

(a,!b)!=![b,!a]

Classic « swap »

!!!!return![45.4,!2.3]
}
assert!la!==!45.4!&&!lo!==!2.3
53

def!(a,!b)!=!['A',!'B']

With types

(a,!b)!=![b,!a]

Classic « swap »


Method
returning a list

!!!!return![45.4,!2.3]
}
assert!la!==!45.4!&&!lo!==!2.3

53

def!(a,!b)!=!['A',!'B']

With types

(a,!b)!=![b,!a]

Classic « swap »


Method
returning a list

!!!!return![45.4,!2.3]
}
Destructuring
assert!la!==!45.4!&&!lo!==!2.3

53

class!Point!{
!!!!double!x,!y
!!!!double!getAt(int!idx)!{
!!!!!!!!if!(idx!==!0)!x
!!!!!!!!else!if!(idx!==!1)!y
!!!!!!!!else!throw!new!Exception("Wrong!index")
!!!!}
}
def!(x,!y)!=!new!Point(x:!48.3,!y:!3.5)
assert!x!==!48.3!&&!y!==!3.5
54

class!Point!{
!!!!double!x,!y

Method signature
convention: getAt(int)

!!!!!!!!if!(idx!==!0)!x
!!!!!!!!else!if!(idx!==!1)!y
!!!!}
}
assert!x!==!48.3!&&!y!==!3.5
54

class!Point!{
!!!!double!x,!y

Method signature
convention: getAt(int)

!!!!!!!!if!(idx!==!0)!x
!!!!!!!!else!if!(idx!==!1)!y
!!!!}
}
Transparent destructuring
assert!x!==!48.3!&&!y!==!3.5
54

Builders and GPath expressions
import!groovy.xml.*
!!!!head!{
!!!!}
!!!!body!{
!!!!!!!!!!!!p!"Groovy!won!"
!!!!!!!!}
!!!!}
}
55

import!groovy.xml.*

Hierarchical data
representation

!!!!head!{
!!!!}
!!!!body!{
!!!!!!!!!!!!p!"Groovy!won!"
!!!!!!!!}
!!!!}
}
55

import!groovy.xml.*

Hierarchical data
representation

!!!!head!{
!!!!}
!!!!body!{
!!!!!!!!!!!!p!"Groovy!won!"
!!!!!!!!}
Closure blocks delimiting
!!!!}
the structure
}
55

import!groovy.xml.*

Hierarchical data
representation

!!!!head!{
!!!!}
Attributes
!!!!body!{
!!!!!!!!!!!!p!"Groovy!won!"
!!!!!!!!}
Closure blocks delimiting
!!!!}
the structure
}
55

Power asserts
def!(a,!b,!c)!=![20,!30,!40]
assert!a!*!(b!c!1)!/!10!==!3!*!c!/!2!+!1

56

Power asserts
def!(a,!b,!c)!=![20,!30,!40]
assert!a!*!(b!c!1)!/!10!==!3!*!c!/!2!+!1
Assertion!failed:!
assert!a!*!(b!c!1)!/!10!==!3!*!c!/!2!+!1
!!!!!!!|!|!!|!|!!!!|!!!!|!!!!|!|!|!!!|
!!!!!!!|!580|!29!!!58!!!false|!|!60!!61
!!!!!!!20!!!30!!!!!!!!!!!!!!!|!40
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!120
! at!script1.run(script1t.groovy:4)
56

Null handling
• Groovy provides a more descriptive
NullPointerException than Java
• Safe navigation with ?.

57

The Truth,
the Groovy Truth!
And what if I could
customize the truth?

Towards Elvis...
def!(x,!y)!=!['MacBook!Pro',!'unknown']

60

Towards Elvis...
if*(x!!=!null!&&!x.size()!>!0)!x!else!y

60

Towards Elvis...
if*(x!&&!x.size())!x!else!y

60

Towards Elvis...
if*(x)!x!else!y

60

Towards Elvis...
if*(x)!x!else!y
x!?!x!:!y

60

Towards Elvis...
if*(x)!x!else!y
x!?!x!:!y
x!?:!y

60

Towards Elvis...
if*(x)!x!else!y
x!?!x!:!y
x!?:!y

Null, empty, zerosized... false,
otherwise true!

60

Towards Elvis...
if*(x)!x!else!y
x!?!x!:!y
x!?:!y

Good old ternary
operator

60

otherwise true!

Towards Elvis...
if*(x)!x!else!y
x!?!x!:!y
x!?:!y

Elvis!

60

Good old ternary
operator

otherwise true!

AST transformations
• Abstract Syntax Tree
– in memory representation of your program
before being compiled into bytecode

• AST transformation == process of transforming
the AST of a program before it’s compiled
• Macro-like compiler hook!

61

Lots of AST transformations...
• Code generation
– @ToString, @EqualsAndHashCode, @Canonical,
@TupleConstructor, @InheritConstructors,
@Category, @IndexedProperty, @Lazy, @Newify

• Class design
– @Delegate, @Immutable, @Memoized,
@Singleton, @Mixin

• Logging
– @Log, @Log4j, @Log4j2, @Slf4j
62

• Safer scripting
– @ConditionalInterrupt, @ThreadInterrupt,
@TimedInterupt

• Compiler directives
– @Field, @PackageScope, @AnnotationCollector,
@DelegatesTo, @TypeChecked,
@CompileStatic, @CompileDynamic

• Swing patterns
– @Bindable, @ListenerList, @Vetoable
63

• Dependencies handling
– @Grab, @GrabConﬁg, @GrabExclude,
@GrabResolver

• Test assistance
– @NotYetImplemented, @ASTTest

64

Immutability
• Implement immutability
by the book
– final class
– tuple-style constructor
– private final backing fields
– defensive copying of collections
– equals() and hashCode() methods
– toString() method
– ...
65

Immutability
• Implement immutability
by the book
– final class
Can be error-prone to
– tuple-style constructor
write immutable
– private final backing fields
classes oneself!
– defensive copying of collections
– equals() and hashCode() methods
– toString() method
– ...
65

Immutability
• A Person class with

public final class Person {
private final String name;
private final int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}

– a String name
– an int age

public String getName() {
return name;
}
public int getAge() {
return age;
}
public int hashCode() {
return age + 31 * name.hashCode();
}
public boolean equals(Object other) {
if (other == null) {
return false;
}
if (this == other) {
return true;
}
if (Person.class != other.getClass()) {
return false;
}
Person otherPerson = (Person)other;
if (!name.equals(otherPerson.getName()) {
return false;
}
if (age != otherPerson.getAge()) {
return false;
}
return true;
}
public String toString() {
return "Person(" + name + ", " + age + ")";
}
}

66

Immutability

Damn
verbose
Java!

this.name = name;
this.age = age;
}

– a String name
– an int age

return name;
}
return age;
}
}
return false;
}
return true;
}
return false;
}
return false;
}
return false;
}
return true;
}
}
}

66

Immutability

Damn
verbose
Java!

this.name = name;
this.age = age;
}

– a String name
– an int age

return name;
}
return age;
}
}
return false;
}
return true;
}
return false;
}
return false;
}
return false;
}
return true;
}

Although it’s also a valid
Groovy program!

}
}

66

@Immutable

import!groovy.transform.*
@Immutable
class!Person!{
!!!!String!name
!!!!int!age
}
67

Memoization
• Cache the result of previous invocations
of closures or methods with the same set
of argument values
@Memoized
long!fib(long!n)!{
!!!!if!(n!==!0)!0
!!!!else!if!(n!==!1)!1
!!!!else!fib(n!c!1)!+!fib(n!c!2)
}
println!fib(40)
68

Memoization
• Cache the result of previous invocations
of closures or methods with the same set
of argument values

Best applied to
side-effect free
functions

@Memoized
long!fib(long!n)!{
!!!!if!(n!==!0)!0
!!!!else!if!(n!==!1)!1
!!!!else!fib(n!c!1)!+!fib(n!c!2)
}
println!fib(40)

68

Groovy allows you
to be lazy

The compiler will do
the job for you

Groovy allows you
to be lazy

More concise, more
readable code

the job for you

Groovy allows you
to be lazy

More concise, more
readable code

the job for you

Less stuff to maintain
and worry about

@TypeChecked and @CompileStatic
• Static type checking with @TypeChecked,
throws compilation errors on...
– typos in method and variable names
– incompatible return types
– wrong type assignments

• Supports ﬁne-grained type inference
– « Least Upper Bound »
– « Flow typing »

70

You can even extend the
static type checker!


70

You can even extend the
static type checker!


70

Type check DSLs or
dynamic features!

• What is type checked can also be compiled
statically with @CompileStatic
– generate the same bytecode as javac
– same performance as Java

71

Pi (π)
Fibonacci
quadrature
Java

191 ms

97 ms

3.6 s

2.x

Static
compilation

197 ms

101 ms

4.3 s

1.8
72

Binary
trees

Primitive
optimizations

360 ms

111 ms

23.7 s

1.7

Static compilation performance

No prim.
optimizations

2590 ms 3220 ms

50.0 s

GVM
GROOVY
ENVIRONMENT

MANAGER

GVM: Groovy enVironment Manager
• The new kid on the block
– http://gvmtool.net/ — @gvmtool

• Manage parallel versions
of the various ecosystem projects
• Supports...
– Groovy, Grails, Griffon, Gradle,Vert.x, Spring Boot

• On Linux, MacOS, Cygwin, Solaris, FreeBSD
81

I’m Spock...
...the Spock testing
framework

Spock example
@Grab('org.spockframework:spockccore:0.7cgroovyc2.0')
import!spock.lang.*
******expect:
!!!!!!!!Math.max(a,!b)!==!c
******where:
!!!!!!!!a!|!b!||!c
!!!!!!!!1!|!3!||!3
!!!!!!!!7!|!4!||!4
!!!!!!!!0!|!0!||!0
!!!!}
}
83

Spock example

@Grab a dependency

import!spock.lang.*
******expect:
!!!!!!!!Math.max(a,!b)!==!c
******where:
!!!!!!!!a!|!b!||!c
!!!!!!!!1!|!3!||!3
!!!!!!!!7!|!4!||!4
!!!!!!!!0!|!0!||!0
!!!!}
}
83

Spock example

@Grab a dependency

import!spock.lang.*
******expect:
!!!!!!!!Math.max(a,!b)!==!c
******where:
!!!!!!!!a!|!b!||!c
!!!!!!!!1!|!3!||!3
!!!!!!!!7!|!4!||!4
!!!!!!!!0!|!0!||!0
!!!!}
}
83

Meaningful test
method names

Spock example

@Grab a dependency

import!spock.lang.*

Meaningful test
method names

******expect:
!!!!!!!!Math.max(a,!b)!==!c
Clever use of labels
******where:
!!!!!!!!a!|!b!||!c
!!!!!!!!1!|!3!||!3
!!!!!!!!7!|!4!||!4
!!!!!!!!0!|!0!||!0
!!!!}
}
83

for BDD style

Spock example

@Grab a dependency

import!spock.lang.*

Meaningful test
method names

******expect:
!!!!!!!!Math.max(a,!b)!==!c
******where:
!!!!!!!!a!|!b!||!c
!!!!!!!!1!|!3!||!3
!!!!!!!!7!|!4!||!4
!!!!!!!!0!|!0!||!0
!!!!}
}
83

for BDD style
Expression to
be asserted

Spock example

@Grab a dependency

import!spock.lang.*

Meaningful test
method names

******expect:
!!!!!!!!Math.max(a,!b)!==!c
******where:
!!!!!!!!a!|!b!||!c
!!!!!!!!1!|!3!||!3
!!!!!!!!7!|!4!||!4
!!!!!!!!0!|!0!||!0
!!!!}
}
83

for BDD style
Cute datadriven tests!

Expression to
be asserted

@GrabResolver("https://oss.jfrog.org/artifactory/repo")
@Grab("org.ratpackcframework:ratpackcgroovy:0.9.0cSNAPSHOT")
import!static!org.ratpackframework.groovy.RatpackScript.ratpack
import!static!org.ratpackframework.groovy.Template.groovyTemplate
ratpack!{
!!!!handlers!{
!!!!!!!!get!{
!!!!!!!!!!!!response.send!"Welcome!"
!!!!!!!!}
!!!!!!!!get("date")!{
!!!!!!!!!!!!render!groovyTemplate("date.html")
!!!!!!!!}
!!!!!!!!assets!"public"
!!!!}
}

@GrabResolver("https://oss.jfrog.org/artifactory/repo")
@Grab("org.ratpackcframework:ratpackcgroovy:0.9.0cSNAPSHOT")
import!static!org.ratpackframework.groovy.RatpackScript.ratpack
import!static!org.ratpackframework.groovy.Template.groovyTemplate
ratpack!{
!!!!handlers!{
!!!!!!!!get!{
!!!!!!!!!!!!response.send!"Welcome!"
!!!!!!!!}

Lightweight Netty-based
web app toolkit

!!!!!!!!get("date")!{
!!!!!!!!!!!!render!groovyTemplate("date.html")
!!!!!!!!}
!!!!!!!!assets!"public"
!!!!}
}

Geb
• Browser automation solution
• WebDriver + jQuery selectors + Groovy
• Handy for
– scripting, scraping, automation...
– functional / web / acceptance testing
• when integrated with JUnit, TestNG or Spock

85

Geb — Example
import!geb.Browser
Browser.drive!{
!!!!go!"http://myapp.com/login"
!!!!assert!$("h1").text()!==!"Please!Login"
!!!!$("form.login").with!{
!!!!!!!!username!=!"admin"
!!!!!!!!password!=!"password"
!!!!!!!!login().click()
!!!!}
!!!!assert!$("h1").text()!==!
!!!!!!!!"Admin!Section"
}

86

Geb — Example

Drive the browser
to this site

import!geb.Browser
Browser.drive!{
!!!!}
!!!!assert!$("h1").text()!==!
}

86

Geb — Example

Drive the browser
to this site

import!geb.Browser
Browser.drive!{

Check the content
of the title

!!!!}
!!!!assert!$("h1").text()!==!
}

86

Geb — Example

Drive the browser
to this site

import!geb.Browser
Browser.drive!{

Check the content
of the title

!!!!}
!!!!assert!$("h1").text()!==!
}

86

Find & fill in
the form

Geb — Example

Drive the browser
to this site

import!geb.Browser
Browser.drive!{

Check the content
of the title

!!!!}
!!!!assert!$("h1").text()!==!
}

86

Find & fill in
the form
Submit the
form

Geb — Example

Drive the browser
to this site

import!geb.Browser
Browser.drive!{

Check the content
of the title

!!!!}
!!!!assert!$("h1").text()!==!
}

Find & fill in
the form
Submit the
form

In the admin section, yeah!
86

Geb — With page objects and Spock
import!geb.spock.GebSpec
class!GoogleWikipediaSpec!extends!GebSpec!{
!!!!def!"first!result!for!wikipedia!search!should!be!wikipedia"()!{
********given:
!!!!!!!!to!GoogleHomePage
********expect:
!!!!!!!!at!GoogleHomePage
********when:
!!!!!!!!search.field.value("wikipedia")
********then:
!!!!!!!!waitFor!{!at!GoogleResultsPage!}
********and:
!!!!!!!!firstResultLink.text()!==!"Wikipedia"
********when:
!!!!!!!!firstResultLink.click()
********then:
!!!!!!!!waitFor!{!at!WikipediaPage!}
!!!!}
}

87


With page objects
********given:
********expect:
********when:
********then:
********and:
********when:
********then:
!!!!}
}

87


With page objects
********given:
********expect:

BDD style: given/when/then

********when:
********then:
********and:
********when:
********then:
!!!!}
}

87


With page objects
********given:
********expect:
********when:

BDD style: given/when/then
Wait for slow loading pages

********then:
********and:
********when:
********then:
!!!!}
}

87

Java’s best friend
• Java derived syntax
– Flat learning curve
– Easy to learn

• But goes beyond Java
– Concise, expressive, readable
– Fit for Domain-Speciﬁc Languages

• Seamless & transparent Java integration
– Mix and match Groovy and Java classes (joint compil.)
– No language barrier to cross
89

Groovy’s nature
• Object oriented dynamic language...
• But...
– as type safe as you want it — static type checking
– as fast as you need it — static compilation
– as functional as you make it — closures...

90

Groovy use cases
• Scripting tasks, build automation
• Extension points for customizing/conﬁguring apps
• Business languages & Domain-Speciﬁc Languages
• Full blown apps
– for desktop with Griffon
– for the web with Grails, Ratpack, Gaelyk
– for web reactive programming with reactor
91

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