DataFaker The most powerful fake data generation library @eliasnogueira

ELIAS NOGUEIRA Senior Principal Software Engineer Brazil Java Champion Oracle ACE Pro Java Magazine NL Editor

The problem we will solve

address=XmcWoqivEzSoUwEksGNjlzrjUmWKKCIDOTsDnPAlHPQMJaWYzt age=0 Meaningful data Generate random fixed data name=John Doe [email protected] No data requirement focus https://speakerdeck.com/eliasnogueira/managing-test-data https://speakerdeck.com/eliasnogueira/managing-test-data

{ "name": "gAqXOiRGeYiYFHcUOBODzfIQyMmJhUIBJQKqbgamCAlrNlPgxb", "age": 99, "addresses": [ { "line_1": "XGWCgCJcufQlNeqBeXzjcWEVDeIVkJ", "line_2": "sHMZCiNipBcZyfMGZTYYVfRZCTrQySLOwpJSQdHZhrsWznnsSn", "building_number": "64126021", "postcode": "vUdzNyBenk", "town_or_city": "jbeZQMWfKgxEVUYNlJSr", "district": "LOoKXHKNppaFUBy", "country": "AcqwFQFIEB", "latitude": 1.1111111, "longitude": -2.222222 } ] } All the problems together

How we will solve it?

Address (any pieces), latitude, longitude IBAN, BIC, credit card, stock, routing number DataFaker Any composition, suffix, prefix Credit card, security code, card type Domain, e-mail, image, IP address, password Different providers to help you! Names Address Finance Business Internet +200 Generating fake data for the JVM (Java, Kotlin, Groovy) has never been easier!

Generation in a nutshell The connections between the YML file and the code. Sometimes it has some logic. This file contains the data generated by DataFaker. It supports different locales. YML file Provider class

DataFaker Concepts Base Providers Transformation Schemas Real life usage How to create yours Repeatable Results

Base Providers

Base Providers Generator Code Output Names faker.name().fullName() Clemente Lemke Address faker.address().fullAddress() Apt. 984 62551 Brooke Expressway, Chinmouth, WA 55746 Finance faker.finance().iban() NL31RJCK5939950627 Business faker.business().creditCardNumber() 5202-4875-5936-5334 Internet faker.internet().image() https://picsum.photos/640/480 More than 200 providers available

Repeatable Results

Transformation Schemas @Test public void predictableData() { Faker fakerPredictable = new Faker(new Random(0)); String name = fakerPredictable.name().fullName(); String address = fakerPredictable.address().fullAddress(); LOGGER.info(name); LOGGER.info(address); } [INFO ] Miss Lavina Waelchi [INFO ] 194 Allison Drive, Strackeview, MT 10384 Output

Transformation Schemas

Transformation Schemas CSV JSON SQL YAML XML Java Schema is a set of rules describing what should be done to transform data from Datafaker representation to one of the supported formats

Transformation Schemas Faker faker = new Faker(); Schema personSchema = Schema.of( field("name", () -> faker.name().nameWithMiddle()), field("username", () -> faker.internet().username()), field("email", () -> faker.internet().emailAddress()), field("password", () -> faker.internet().password(8, 12)) );

Transformation Schemas /* * SQL Data Transformation */ SqlTransformer sqlTransformer = new SqlTransformer.SqlTransformerBuilder() .batch(5) .tableName("MY_TABLE") .dialect(SqlDialect.POSTGRES) .build(); String output = sqlTransformer.generate(personSchema, 10); /* * CSV Data Transformation */ CsvTransformer csvTransformer = CsvTransformer.builder().header(true).separator(COMMA).build(); String csvOutput = csvTransformer.generate(retrieveSchema(), 5);

Transformation Schemas CSV Output "name","username","email","password" "Myra Lemke Zulauf","giovanni.hartmann","[email protected]","49uv48051" "Elijah Kautzer Hudson","carlota.haag","[email protected]","292ka97i5" "Loraine Simonis Dach","renee.ondricka","[email protected]","9vt5tr7i0" "George Stiedemann Roob","idella.crist","[email protected]","4134aqt8q" "Derek Runolfsdottir Spinka","marcel.simonis","[email protected]","r3073b71j7" SQL Output INSERT INTO MY_TABLE ("name", "username", "email", "password") VALUES ('Yuki Osinski Hagenes', 'billie.collins', '[email protected]', 'def314ac7w9'), ('Kenny Kessler Rice V', 'minh.schneider', '[email protected]', '1ij8xjive6'), ('Cory Tromp Konopelski', 'yuko.russel', '[email protected]', 'h94nbfv99'), ('Lonna Borer Casper', 'joyce.mclaughlin', '[email protected]', '33sopr94vg'), ('Mr. Sammy Braun Langworth', 'darren.osinski', '[email protected]', '39j16kik8');

Real Life Usage

Real Life Usage Tool To randomize meaningful data in the Factory Test Data Factory Factory Factory Pattern to generate different data scenarios Model Model object using the Build pattern to hold data

Real Life Usage public final class UserDataFactory { private static final Faker FAKER = new Faker(); public static User validUser() { return User.builder() .name(FAKER.name().nameWithMiddle()) .username(FAKER.internet().username()) .email(FAKER.internet().emailAddress()) .password(FAKER.internet().password()) .build(); } }

Real Life Usage public final class UserDataFactory { private static final Faker FAKER = new Faker(); public static User passwordNotMatchMinRequirement() { return User.builder() .name(FAKER.name().nameWithMiddle()) .username(FAKER.internet().username()) .email(FAKER.internet().emailAddress()) .password(FAKER.internet().password(1,11)) .build(); } }

How to Create Yours

How To Create Yours [private] Step 1 Create the YAML file with data Step 2 Create the Provider class Step 3 Create the Custom Faker

How To Create Yours [private] Step 1 Create an yml file in the src/main/resources en: faker: java-conferences: names: - "Devoxx UK" - "DevNexus" - "Devoxx Belgium" - "JavaZone" - "Jfall" - "Jfokus" - "JavaLand" - "JNation" - "JPrime" - "JCON" en is the locale faker is the reference for the generation java-conferences is the provider key names is the list of values

How To Create Yours [private] Step 2 Create the provider class public class JavaConferences extends AbstractProvider { protected JavaConferences(BaseProviders faker) { super(faker); faker.addPath(Locale.ENGLISH, Paths.get( getClass().getClassLoader().getResource("java-conferences.yml").getPath())); } public String name() { return resolve("java-conferences.names"); } } The constructor make the connection between the class and the YML file

public class JavaConferences extends AbstractProvider { protected JavaConferences(BaseProviders faker) { super(faker); faker.addPath(Locale.ENGLISH, Paths.get( getClass().getClassLoader().getResource("java-conferences.yml").getPath())); } public String name() { return resolve("java-conferences.names"); } } How To Create Yours [private] Step 2 Create the provider class Then we use the provider key followed by the generators which will return one of the data present in the YML file

How To Create Yours [private] Step 3 Create the custom Faker public class MyCustomFaker extends Faker { public JavaConferences javaConferences() { return getProvider(JavaConferences.class, JavaConferences::new, this); } }

How To Create Yours [private] Usage Use the custom faker to generate your private data @Test @DisplayName("Should generate a Java event") void generateJavaEvent() { var javaEvent = myCustomFaker.javaConferences().name(); var country = myCustomFaker.country().name(); LOGGER.info(javaEvent); LOGGER.info(country); assertThat(javaEvent).isNotEmpty(); assertThat(country).isNotEmpty(); }

How To Move Yours to DataFaker Step 1 Create the YAML file with data Step 2 Create the Provider class Step 3 Add the yaml file to the service file Step 4 Add it to the BaseProviders

How To Move Yours to DataFaker Step 1 Create an yml file in the src/main/resources en: faker: java-conferences: names: - "Devoxx UK" - "DevNexus" - "Devoxx Belgium" - "JavaZone" - "Jfall" - "Jfokus" - "JavaLand" - "JNation" - "JPrime" - "JCON" en is the locale faker is the reference for the generation java-conferences is the provider key names is the list of values

How To Move Yours to DataFaker Step 2 Create the provider class in the src/main/java/net.datafaker.providers.base public class JavaConferences extends AbstractProvider { protected JavaConferences(BaseProviders faker) { super(faker); } public String name() { return resolve("java-conferences.names"); } } The constructor make the connection between the class and the YML file

How To Move Yours to DataFaker Step 2 public class JavaConferences extends AbstractProvider { protected JavaConferences(BaseProviders faker) { super(faker); } public String name() { return resolve("java-conferences.names"); } } Then we use the provider key followed by the generators which will return one of the data present in the YML file Create the provider class in the src/main/java/net.datafaker.providers.base

How To Move Yours to DataFaker Step 3 Add the YML file name in the src/main/java/net.datafaker.service.files public class EnFile { // previous code ignored private static final List FILES = Stream.of( "address.yml", "Ancient.yml", "YOUR_FILE.yml", ).map(EnFile::new).toList();

How To Move Yours to DataFaker Step 4 Add the YML file name in the src/main/java/net.datafaker.providers.base public interface BaseProviders extends ProviderRegistration { default Address address() { return getProvider(Address.class, Address::new); } default JavaConferences javaConferences() { return getProvider(JavaConferences.class, JavaConferences::new); } }

Thanks! Elias Nogueira